<feed xmlns='http://www.w3.org/2005/Atom'>
<title>kernel/linux.git/drivers/net/tun.c, branch v6.12.80</title>
<subtitle>Linux kernel stable tree (mirror)</subtitle>
<id>https://git.radix-linux.su/kernel/linux.git/atom?h=v6.12.80</id>
<link rel='self' href='https://git.radix-linux.su/kernel/linux.git/atom?h=v6.12.80'/>
<link rel='alternate' type='text/html' href='https://git.radix-linux.su/kernel/linux.git/'/>
<updated>2025-10-02T11:44:09+00:00</updated>
<entry>
<title>net: tun: Update napi-&gt;skb after XDP process</title>
<updated>2025-10-02T11:44:09+00:00</updated>
<author>
<name>Wang Liang</name>
<email>wangliang74@huawei.com</email>
</author>
<published>2025-09-17T11:39:19+00:00</published>
<link rel='alternate' type='text/html' href='https://git.radix-linux.su/kernel/linux.git/commit/?id=953200d56fc23eebf80a5ad9eed6e2e8a3065093'/>
<id>urn:sha1:953200d56fc23eebf80a5ad9eed6e2e8a3065093</id>
<content type='text'>
[ Upstream commit 1091860a16a86ccdd77c09f2b21a5f634f5ab9ec ]

The syzbot report a UAF issue:

  BUG: KASAN: slab-use-after-free in skb_reset_mac_header include/linux/skbuff.h:3150 [inline]
  BUG: KASAN: slab-use-after-free in napi_frags_skb net/core/gro.c:723 [inline]
  BUG: KASAN: slab-use-after-free in napi_gro_frags+0x6e/0x1030 net/core/gro.c:758
  Read of size 8 at addr ffff88802ef22c18 by task syz.0.17/6079
  CPU: 0 UID: 0 PID: 6079 Comm: syz.0.17 Not tainted syzkaller #0 PREEMPT(full)
  Call Trace:
   &lt;TASK&gt;
   dump_stack_lvl+0x189/0x250 lib/dump_stack.c:120
   print_address_description mm/kasan/report.c:378 [inline]
   print_report+0xca/0x240 mm/kasan/report.c:482
   kasan_report+0x118/0x150 mm/kasan/report.c:595
   skb_reset_mac_header include/linux/skbuff.h:3150 [inline]
   napi_frags_skb net/core/gro.c:723 [inline]
   napi_gro_frags+0x6e/0x1030 net/core/gro.c:758
   tun_get_user+0x28cb/0x3e20 drivers/net/tun.c:1920
   tun_chr_write_iter+0x113/0x200 drivers/net/tun.c:1996
   new_sync_write fs/read_write.c:593 [inline]
   vfs_write+0x5c9/0xb30 fs/read_write.c:686
   ksys_write+0x145/0x250 fs/read_write.c:738
   do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
   do_syscall_64+0xfa/0x3b0 arch/x86/entry/syscall_64.c:94
   entry_SYSCALL_64_after_hwframe+0x77/0x7f
   &lt;/TASK&gt;

  Allocated by task 6079:
   kasan_save_stack mm/kasan/common.c:47 [inline]
   kasan_save_track+0x3e/0x80 mm/kasan/common.c:68
   unpoison_slab_object mm/kasan/common.c:330 [inline]
   __kasan_mempool_unpoison_object+0xa0/0x170 mm/kasan/common.c:558
   kasan_mempool_unpoison_object include/linux/kasan.h:388 [inline]
   napi_skb_cache_get+0x37b/0x6d0 net/core/skbuff.c:295
   __alloc_skb+0x11e/0x2d0 net/core/skbuff.c:657
   napi_alloc_skb+0x84/0x7d0 net/core/skbuff.c:811
   napi_get_frags+0x69/0x140 net/core/gro.c:673
   tun_napi_alloc_frags drivers/net/tun.c:1404 [inline]
   tun_get_user+0x77c/0x3e20 drivers/net/tun.c:1784
   tun_chr_write_iter+0x113/0x200 drivers/net/tun.c:1996
   new_sync_write fs/read_write.c:593 [inline]
   vfs_write+0x5c9/0xb30 fs/read_write.c:686
   ksys_write+0x145/0x250 fs/read_write.c:738
   do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
   do_syscall_64+0xfa/0x3b0 arch/x86/entry/syscall_64.c:94
   entry_SYSCALL_64_after_hwframe+0x77/0x7f

  Freed by task 6079:
   kasan_save_stack mm/kasan/common.c:47 [inline]
   kasan_save_track+0x3e/0x80 mm/kasan/common.c:68
   kasan_save_free_info+0x46/0x50 mm/kasan/generic.c:576
   poison_slab_object mm/kasan/common.c:243 [inline]
   __kasan_slab_free+0x5b/0x80 mm/kasan/common.c:275
   kasan_slab_free include/linux/kasan.h:233 [inline]
   slab_free_hook mm/slub.c:2422 [inline]
   slab_free mm/slub.c:4695 [inline]
   kmem_cache_free+0x18f/0x400 mm/slub.c:4797
   skb_pp_cow_data+0xdd8/0x13e0 net/core/skbuff.c:969
   netif_skb_check_for_xdp net/core/dev.c:5390 [inline]
   netif_receive_generic_xdp net/core/dev.c:5431 [inline]
   do_xdp_generic+0x699/0x11a0 net/core/dev.c:5499
   tun_get_user+0x2523/0x3e20 drivers/net/tun.c:1872
   tun_chr_write_iter+0x113/0x200 drivers/net/tun.c:1996
   new_sync_write fs/read_write.c:593 [inline]
   vfs_write+0x5c9/0xb30 fs/read_write.c:686
   ksys_write+0x145/0x250 fs/read_write.c:738
   do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
   do_syscall_64+0xfa/0x3b0 arch/x86/entry/syscall_64.c:94
   entry_SYSCALL_64_after_hwframe+0x77/0x7f

After commit e6d5dbdd20aa ("xdp: add multi-buff support for xdp running in
generic mode"), the original skb may be freed in skb_pp_cow_data() when
XDP program was attached, which was allocated in tun_napi_alloc_frags().
However, the napi-&gt;skb still point to the original skb, update it after
XDP process.

Reported-by: syzbot+64e24275ad95a915a313@syzkaller.appspotmail.com
Closes: https://syzkaller.appspot.com/bug?extid=64e24275ad95a915a313
Fixes: e6d5dbdd20aa ("xdp: add multi-buff support for xdp running in generic mode")
Signed-off-by: Wang Liang &lt;wangliang74@huawei.com&gt;
Reviewed-by: Willem de Bruijn &lt;willemb@google.com&gt;
Link: https://patch.msgid.link/20250917113919.3991267-1-wangliang74@huawei.com
Signed-off-by: Jakub Kicinski &lt;kuba@kernel.org&gt;
Signed-off-by: Sasha Levin &lt;sashal@kernel.org&gt;
</content>
</entry>
<entry>
<title>tun: revert fix group permission check</title>
<updated>2025-02-17T09:05:02+00:00</updated>
<author>
<name>Willem de Bruijn</name>
<email>willemb@google.com</email>
</author>
<published>2025-02-04T16:10:06+00:00</published>
<link rel='alternate' type='text/html' href='https://git.radix-linux.su/kernel/linux.git/commit/?id=e36364d5d4344eddc3a25b4f2e0a3876ec1de82f'/>
<id>urn:sha1:e36364d5d4344eddc3a25b4f2e0a3876ec1de82f</id>
<content type='text'>
[ Upstream commit a70c7b3cbc0688016810bb2e0b9b8a0d6a530045 ]

This reverts commit 3ca459eaba1bf96a8c7878de84fa8872259a01e3.

The blamed commit caused a regression when neither tun-&gt;owner nor
tun-&gt;group is set. This is intended to be allowed, but now requires
CAP_NET_ADMIN.

Discussion in the referenced thread pointed out that the original
issue that prompted this patch can be resolved in userspace.

The relaxed access control may also make a device accessible when it
previously wasn't, while existing users may depend on it to not be.

This is a clean pure git revert, except for fixing the indentation on
the gid_valid line that checkpatch correctly flagged.

Fixes: 3ca459eaba1b ("tun: fix group permission check")
Link: https://lore.kernel.org/netdev/CAFqZXNtkCBT4f+PwyVRmQGoT3p1eVa01fCG_aNtpt6dakXncUg@mail.gmail.com/
Signed-off-by: Willem de Bruijn &lt;willemb@google.com&gt;
Cc: Ondrej Mosnacek &lt;omosnace@redhat.com&gt;
Cc: Stas Sergeev &lt;stsp2@yandex.ru&gt;
Link: https://patch.msgid.link/20250204161015.739430-1-willemdebruijn.kernel@gmail.com
Signed-off-by: Jakub Kicinski &lt;kuba@kernel.org&gt;
Signed-off-by: Sasha Levin &lt;sashal@kernel.org&gt;
</content>
</entry>
<entry>
<title>tun: fix group permission check</title>
<updated>2025-02-17T09:04:50+00:00</updated>
<author>
<name>Stas Sergeev</name>
<email>stsp2@yandex.ru</email>
</author>
<published>2024-12-05T07:36:14+00:00</published>
<link rel='alternate' type='text/html' href='https://git.radix-linux.su/kernel/linux.git/commit/?id=5c2b1d93861316422736dfbd787226dfd3c12af2'/>
<id>urn:sha1:5c2b1d93861316422736dfbd787226dfd3c12af2</id>
<content type='text'>
[ Upstream commit 3ca459eaba1bf96a8c7878de84fa8872259a01e3 ]

Currently tun checks the group permission even if the user have matched.
Besides going against the usual permission semantic, this has a
very interesting implication: if the tun group is not among the
supplementary groups of the tun user, then effectively no one can
access the tun device. CAP_SYS_ADMIN still can, but its the same as
not setting the tun ownership.

This patch relaxes the group checking so that either the user match
or the group match is enough. This avoids the situation when no one
can access the device even though the ownership is properly set.

Also I simplified the logic by removing the redundant inversions:
tun_not_capable() --&gt; !tun_capable()

Signed-off-by: Stas Sergeev &lt;stsp2@yandex.ru&gt;
Reviewed-by: Willem de Bruijn &lt;willemb@google.com&gt;
Acked-by: Jason Wang &lt;jasowang@redhat.com&gt;
Link: https://patch.msgid.link/20241205073614.294773-1-stsp2@yandex.ru
Signed-off-by: Jakub Kicinski &lt;kuba@kernel.org&gt;
Signed-off-by: Sasha Levin &lt;sashal@kernel.org&gt;
</content>
</entry>
<entry>
<title>ptr_ring: do not block hard interrupts in ptr_ring_resize_multiple()</title>
<updated>2025-02-08T08:57:07+00:00</updated>
<author>
<name>Eric Dumazet</name>
<email>edumazet@google.com</email>
</author>
<published>2024-12-17T13:51:21+00:00</published>
<link rel='alternate' type='text/html' href='https://git.radix-linux.su/kernel/linux.git/commit/?id=3257dac521d0ac6653108c755141dce634bb8ff2'/>
<id>urn:sha1:3257dac521d0ac6653108c755141dce634bb8ff2</id>
<content type='text'>
[ Upstream commit a126061c80d5efb4baef4bcf346094139cd81df6 ]

Jakub added a lockdep_assert_no_hardirq() check in __page_pool_put_page()
to increase test coverage.

syzbot found a splat caused by hard irq blocking in
ptr_ring_resize_multiple() [1]

As current users of ptr_ring_resize_multiple() do not require
hard irqs being masked, replace it to only block BH.

Rename helpers to better reflect they are safe against BH only.

- ptr_ring_resize_multiple() to ptr_ring_resize_multiple_bh()
- skb_array_resize_multiple() to skb_array_resize_multiple_bh()

[1]

WARNING: CPU: 1 PID: 9150 at net/core/page_pool.c:709 __page_pool_put_page net/core/page_pool.c:709 [inline]
WARNING: CPU: 1 PID: 9150 at net/core/page_pool.c:709 page_pool_put_unrefed_netmem+0x157/0xa40 net/core/page_pool.c:780
Modules linked in:
CPU: 1 UID: 0 PID: 9150 Comm: syz.1.1052 Not tainted 6.11.0-rc3-syzkaller-00202-gf8669d7b5f5d #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/06/2024
RIP: 0010:__page_pool_put_page net/core/page_pool.c:709 [inline]
RIP: 0010:page_pool_put_unrefed_netmem+0x157/0xa40 net/core/page_pool.c:780
Code: 74 0e e8 7c aa fb f7 eb 43 e8 75 aa fb f7 eb 3c 65 8b 1d 38 a8 6a 76 31 ff 89 de e8 a3 ae fb f7 85 db 74 0b e8 5a aa fb f7 90 &lt;0f&gt; 0b 90 eb 1d 65 8b 1d 15 a8 6a 76 31 ff 89 de e8 84 ae fb f7 85
RSP: 0018:ffffc9000bda6b58 EFLAGS: 00010083
RAX: ffffffff8997e523 RBX: 0000000000000000 RCX: 0000000000040000
RDX: ffffc9000fbd0000 RSI: 0000000000001842 RDI: 0000000000001843
RBP: 0000000000000000 R08: ffffffff8997df2c R09: 1ffffd40003a000d
R10: dffffc0000000000 R11: fffff940003a000e R12: ffffea0001d00040
R13: ffff88802e8a4000 R14: dffffc0000000000 R15: 00000000ffffffff
FS:  00007fb7aaf716c0(0000) GS:ffff8880b9300000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fa15a0d4b72 CR3: 00000000561b0000 CR4: 00000000003506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 &lt;TASK&gt;
 tun_ptr_free drivers/net/tun.c:617 [inline]
 __ptr_ring_swap_queue include/linux/ptr_ring.h:571 [inline]
 ptr_ring_resize_multiple_noprof include/linux/ptr_ring.h:643 [inline]
 tun_queue_resize drivers/net/tun.c:3694 [inline]
 tun_device_event+0xaaf/0x1080 drivers/net/tun.c:3714
 notifier_call_chain+0x19f/0x3e0 kernel/notifier.c:93
 call_netdevice_notifiers_extack net/core/dev.c:2032 [inline]
 call_netdevice_notifiers net/core/dev.c:2046 [inline]
 dev_change_tx_queue_len+0x158/0x2a0 net/core/dev.c:9024
 do_setlink+0xff6/0x41f0 net/core/rtnetlink.c:2923
 rtnl_setlink+0x40d/0x5a0 net/core/rtnetlink.c:3201
 rtnetlink_rcv_msg+0x73f/0xcf0 net/core/rtnetlink.c:6647
 netlink_rcv_skb+0x1e3/0x430 net/netlink/af_netlink.c:2550

Fixes: ff4e538c8c3e ("page_pool: add a lockdep check for recycling in hardirq")
Reported-by: syzbot+f56a5c5eac2b28439810@syzkaller.appspotmail.com
Closes: https://lore.kernel.org/netdev/671e10df.050a0220.2b8c0f.01cf.GAE@google.com/T/
Signed-off-by: Eric Dumazet &lt;edumazet@google.com&gt;
Acked-by: Michael S. Tsirkin &lt;mst@redhat.com&gt;
Acked-by: Jason Wang &lt;jasowang@redhat.com&gt;
Link: https://patch.msgid.link/20241217135121.326370-1-edumazet@google.com
Signed-off-by: Jakub Kicinski &lt;kuba@kernel.org&gt;
Signed-off-by: Sasha Levin &lt;sashal@kernel.org&gt;
</content>
</entry>
<entry>
<title>net: tun: fix tun_napi_alloc_frags()</title>
<updated>2024-12-27T13:02:07+00:00</updated>
<author>
<name>Eric Dumazet</name>
<email>edumazet@google.com</email>
</author>
<published>2024-12-12T22:22:47+00:00</published>
<link rel='alternate' type='text/html' href='https://git.radix-linux.su/kernel/linux.git/commit/?id=4f393ea1e2f9c3b646d00572dd92c48b1869c65f'/>
<id>urn:sha1:4f393ea1e2f9c3b646d00572dd92c48b1869c65f</id>
<content type='text'>
commit 429fde2d81bcef0ebab002215358955704586457 upstream.

syzbot reported the following crash [1]

Issue came with the blamed commit. Instead of going through
all the iov components, we keep using the first one
and end up with a malformed skb.

[1]

kernel BUG at net/core/skbuff.c:2849 !
Oops: invalid opcode: 0000 [#1] PREEMPT SMP KASAN PTI
CPU: 0 UID: 0 PID: 6230 Comm: syz-executor132 Not tainted 6.13.0-rc1-syzkaller-00407-g96b6fcc0ee41 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 11/25/2024
 RIP: 0010:__pskb_pull_tail+0x1568/0x1570 net/core/skbuff.c:2848
Code: 38 c1 0f 8c 32 f1 ff ff 4c 89 f7 e8 92 96 74 f8 e9 25 f1 ff ff e8 e8 ae 09 f8 48 8b 5c 24 08 e9 eb fb ff ff e8 d9 ae 09 f8 90 &lt;0f&gt; 0b 66 0f 1f 44 00 00 90 90 90 90 90 90 90 90 90 90 90 90 90 90
RSP: 0018:ffffc90004cbef30 EFLAGS: 00010293
RAX: ffffffff8995c347 RBX: 00000000fffffff2 RCX: ffff88802cf45a00
RDX: 0000000000000000 RSI: 00000000fffffff2 RDI: 0000000000000000
RBP: ffff88807df0c06a R08: ffffffff8995b084 R09: 1ffff1100fbe185c
R10: dffffc0000000000 R11: ffffed100fbe185d R12: ffff888076e85d50
R13: ffff888076e85c80 R14: ffff888076e85cf4 R15: ffff888076e85c80
FS:  00007f0dca6ea6c0(0000) GS:ffff8880b8600000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f0dca6ead58 CR3: 00000000119da000 CR4: 00000000003526f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 &lt;TASK&gt;
  skb_cow_data+0x2da/0xcb0 net/core/skbuff.c:5284
  tipc_aead_decrypt net/tipc/crypto.c:894 [inline]
  tipc_crypto_rcv+0x402/0x24e0 net/tipc/crypto.c:1844
  tipc_rcv+0x57e/0x12a0 net/tipc/node.c:2109
  tipc_l2_rcv_msg+0x2bd/0x450 net/tipc/bearer.c:668
  __netif_receive_skb_list_ptype net/core/dev.c:5720 [inline]
  __netif_receive_skb_list_core+0x8b7/0x980 net/core/dev.c:5762
  __netif_receive_skb_list net/core/dev.c:5814 [inline]
  netif_receive_skb_list_internal+0xa51/0xe30 net/core/dev.c:5905
  gro_normal_list include/net/gro.h:515 [inline]
  napi_complete_done+0x2b5/0x870 net/core/dev.c:6256
  napi_complete include/linux/netdevice.h:567 [inline]
  tun_get_user+0x2ea0/0x4890 drivers/net/tun.c:1982
  tun_chr_write_iter+0x10d/0x1f0 drivers/net/tun.c:2057
 do_iter_readv_writev+0x600/0x880
  vfs_writev+0x376/0xba0 fs/read_write.c:1050
  do_writev+0x1b6/0x360 fs/read_write.c:1096
  do_syscall_x64 arch/x86/entry/common.c:52 [inline]
  do_syscall_64+0xf3/0x230 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

Fixes: de4f5fed3f23 ("iov_iter: add iter_iovec() helper")
Reported-by: syzbot+4f66250f6663c0c1d67e@syzkaller.appspotmail.com
Closes: https://lore.kernel.org/netdev/675b61aa.050a0220.599f4.00bb.GAE@google.com/T/#u
Cc: stable@vger.kernel.org
Signed-off-by: Eric Dumazet &lt;edumazet@google.com&gt;
Reviewed-by: Joe Damato &lt;jdamato@fastly.com&gt;
Reviewed-by: Jens Axboe &lt;axboe@kernel.dk&gt;
Acked-by: Willem de Bruijn &lt;willemb@google.com&gt;
Acked-by: Michael S. Tsirkin &lt;mst@redhat.com&gt;
Link: https://patch.msgid.link/20241212222247.724674-1-edumazet@google.com
Signed-off-by: Jakub Kicinski &lt;kuba@kernel.org&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;
</content>
</entry>
<entry>
<title>[tree-wide] finally take no_llseek out</title>
<updated>2024-09-27T15:18:43+00:00</updated>
<author>
<name>Al Viro</name>
<email>viro@zeniv.linux.org.uk</email>
</author>
<published>2024-09-27T01:56:11+00:00</published>
<link rel='alternate' type='text/html' href='https://git.radix-linux.su/kernel/linux.git/commit/?id=cb787f4ac0c2e439ea8d7e6387b925f74576bdf8'/>
<id>urn:sha1:cb787f4ac0c2e439ea8d7e6387b925f74576bdf8</id>
<content type='text'>
no_llseek had been defined to NULL two years ago, in commit 868941b14441
("fs: remove no_llseek")

To quote that commit,

  At -rc1 we'll need do a mechanical removal of no_llseek -

  git grep -l -w no_llseek | grep -v porting.rst | while read i; do
	sed -i '/\&lt;no_llseek\&gt;/d' $i
  done

  would do it.

Unfortunately, that hadn't been done.  Linus, could you do that now, so
that we could finally put that thing to rest? All instances are of the
form
	.llseek = no_llseek,
so it's obviously safe.

Signed-off-by: Al Viro &lt;viro@zeniv.linux.org.uk&gt;
Signed-off-by: Linus Torvalds &lt;torvalds@linux-foundation.org&gt;
</content>
</entry>
<entry>
<title>Merge tag 'vfs-6.12.file' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs</title>
<updated>2024-09-16T07:14:02+00:00</updated>
<author>
<name>Linus Torvalds</name>
<email>torvalds@linux-foundation.org</email>
</author>
<published>2024-09-16T07:14:02+00:00</published>
<link rel='alternate' type='text/html' href='https://git.radix-linux.su/kernel/linux.git/commit/?id=3352633ce6b221d64bf40644d412d9670e7d56e3'/>
<id>urn:sha1:3352633ce6b221d64bf40644d412d9670e7d56e3</id>
<content type='text'>
Pull vfs file updates from Christian Brauner:
 "This is the work to cleanup and shrink struct file significantly.

  Right now, (focusing on x86) struct file is 232 bytes. After this
  series struct file will be 184 bytes aka 3 cacheline and a spare 8
  bytes for future extensions at the end of the struct.

  With struct file being as ubiquitous as it is this should make a
  difference for file heavy workloads and allow further optimizations in
  the future.

   - struct fown_struct was embedded into struct file letting it take up
     32 bytes in total when really it shouldn't even be embedded in
     struct file in the first place. Instead, actual users of struct
     fown_struct now allocate the struct on demand. This frees up 24
     bytes.

   - Move struct file_ra_state into the union containg the cleanup hooks
     and move f_iocb_flags out of the union. This closes a 4 byte hole
     we created earlier and brings struct file to 192 bytes. Which means
     struct file is 3 cachelines and we managed to shrink it by 40
     bytes.

   - Reorder struct file so that nothing crosses a cacheline.

     I suspect that in the future we will end up reordering some members
     to mitigate false sharing issues or just because someone does
     actually provide really good perf data.

   - Shrinking struct file to 192 bytes is only part of the work.

     Files use a slab that is SLAB_TYPESAFE_BY_RCU and when a kmem cache
     is created with SLAB_TYPESAFE_BY_RCU the free pointer must be
     located outside of the object because the cache doesn't know what
     part of the memory can safely be overwritten as it may be needed to
     prevent object recycling.

     That has the consequence that SLAB_TYPESAFE_BY_RCU may end up
     adding a new cacheline.

     So this also contains work to add a new kmem_cache_create_rcu()
     function that allows the caller to specify an offset where the
     freelist pointer is supposed to be placed. Thus avoiding the
     implicit addition of a fourth cacheline.

   - And finally this removes the f_version member in struct file.

     The f_version member isn't particularly well-defined. It is mainly
     used as a cookie to detect concurrent seeks when iterating
     directories. But it is also abused by some subsystems for
     completely unrelated things.

     It is mostly a directory and filesystem specific thing that doesn't
     really need to live in struct file and with its wonky semantics it
     really lacks a specific function.

     For pipes, f_version is (ab)used to defer poll notifications until
     a write has happened. And struct pipe_inode_info is used by
     multiple struct files in their -&gt;private_data so there's no chance
     of pushing that down into file-&gt;private_data without introducing
     another pointer indirection.

     But pipes don't rely on f_pos_lock so this adds a union into struct
     file encompassing f_pos_lock and a pipe specific f_pipe member that
     pipes can use. This union of course can be extended to other file
     types and is similar to what we do in struct inode already"

* tag 'vfs-6.12.file' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs: (26 commits)
  fs: remove f_version
  pipe: use f_pipe
  fs: add f_pipe
  ubifs: store cookie in private data
  ufs: store cookie in private data
  udf: store cookie in private data
  proc: store cookie in private data
  ocfs2: store cookie in private data
  input: remove f_version abuse
  ext4: store cookie in private data
  ext2: store cookie in private data
  affs: store cookie in private data
  fs: add generic_llseek_cookie()
  fs: use must_set_pos()
  fs: add must_set_pos()
  fs: add vfs_setpos_cookie()
  s390: remove unused f_version
  ceph: remove unused f_version
  adi: remove unused f_version
  mm: Removed @freeptr_offset to prevent doc warning
  ...
</content>
</entry>
<entry>
<title>netdev_features: convert NETIF_F_LLTX to dev-&gt;lltx</title>
<updated>2024-09-03T09:36:43+00:00</updated>
<author>
<name>Alexander Lobakin</name>
<email>aleksander.lobakin@intel.com</email>
</author>
<published>2024-08-29T12:33:37+00:00</published>
<link rel='alternate' type='text/html' href='https://git.radix-linux.su/kernel/linux.git/commit/?id=00d066a4d4edbe559ba6c35153da71d4b2b8a383'/>
<id>urn:sha1:00d066a4d4edbe559ba6c35153da71d4b2b8a383</id>
<content type='text'>
NETIF_F_LLTX can't be changed via Ethtool and is not a feature,
rather an attribute, very similar to IFF_NO_QUEUE (and hot).
Free one netdev_features_t bit and make it a "hot" private flag.

Signed-off-by: Alexander Lobakin &lt;aleksander.lobakin@intel.com&gt;
Signed-off-by: Paolo Abeni &lt;pabeni@redhat.com&gt;

</content>
</entry>
<entry>
<title>file: reclaim 24 bytes from f_owner</title>
<updated>2024-08-28T11:05:39+00:00</updated>
<author>
<name>Christian Brauner</name>
<email>brauner@kernel.org</email>
</author>
<published>2024-08-09T16:00:01+00:00</published>
<link rel='alternate' type='text/html' href='https://git.radix-linux.su/kernel/linux.git/commit/?id=1934b212615dc617ac84fc306333ab2b9fc3b04f'/>
<id>urn:sha1:1934b212615dc617ac84fc306333ab2b9fc3b04f</id>
<content type='text'>
We do embedd struct fown_struct into struct file letting it take up 32
bytes in total. We could tweak struct fown_struct to be more compact but
really it shouldn't even be embedded in struct file in the first place.

Instead, actual users of struct fown_struct should allocate the struct
on demand. This frees up 24 bytes in struct file.

That will have some potentially user-visible changes for the ownership
fcntl()s. Some of them can now fail due to allocation failures.
Practically, that probably will almost never happen as the allocations
are small and they only happen once per file.

The fown_struct is used during kill_fasync() which is used by e.g.,
pipes to generate a SIGIO signal. Sending of such signals is conditional
on userspace having set an owner for the file using one of the F_OWNER
fcntl()s. Such users will be unaffected if struct fown_struct is
allocated during the fcntl() call.

There are a few subsystems that call __f_setown() expecting
file-&gt;f_owner to be allocated:

(1) tun devices
    file-&gt;f_op-&gt;fasync::tun_chr_fasync()
    -&gt; __f_setown()

    There are no callers of tun_chr_fasync().

(2) tty devices

    file-&gt;f_op-&gt;fasync::tty_fasync()
    -&gt; __tty_fasync()
       -&gt; __f_setown()

    tty_fasync() has no additional callers but __tty_fasync() has. Note
    that __tty_fasync() only calls __f_setown() if the @on argument is
    true. It's called from:

    file-&gt;f_op-&gt;release::tty_release()
    -&gt; tty_release()
       -&gt; __tty_fasync()
          -&gt; __f_setown()

    tty_release() calls __tty_fasync() with @on false
    =&gt; __f_setown() is never called from tty_release().
       =&gt; All callers of tty_release() are safe as well.

    file-&gt;f_op-&gt;release::tty_open()
    -&gt; tty_release()
       -&gt; __tty_fasync()
          -&gt; __f_setown()

    __tty_hangup() calls __tty_fasync() with @on false
    =&gt; __f_setown() is never called from tty_release().
       =&gt; All callers of __tty_hangup() are safe as well.

From the callchains it's obvious that (1) and (2) end up getting called
via file-&gt;f_op-&gt;fasync(). That can happen either through the F_SETFL
fcntl() with the FASYNC flag raised or via the FIOASYNC ioctl(). If
FASYNC is requested and the file isn't already FASYNC then
file-&gt;f_op-&gt;fasync() is called with @on true which ends up causing both
(1) and (2) to call __f_setown().

(1) and (2) are the only subsystems that call __f_setown() from the
file-&gt;f_op-&gt;fasync() handler. So both (1) and (2) have been updated to
allocate a struct fown_struct prior to calling fasync_helper() to
register with the fasync infrastructure. That's safe as they both call
fasync_helper() which also does allocations if @on is true.

The other interesting case are file leases:

(3) file leases
    lease_manager_ops-&gt;lm_setup::lease_setup()
    -&gt; __f_setown()

    Which in turn is called from:

    generic_add_lease()
    -&gt; lease_manager_ops-&gt;lm_setup::lease_setup()
       -&gt; __f_setown()

So here again we can simply make generic_add_lease() allocate struct
fown_struct prior to the lease_manager_ops-&gt;lm_setup::lease_setup()
which happens under a spinlock.

With that the two remaining subsystems that call __f_setown() are:

(4) dnotify
(5) sockets

Both have their own custom ioctls to set struct fown_struct and both
have been converted to allocate a struct fown_struct on demand from
their respective ioctls.

Interactions with O_PATH are fine as well e.g., when opening a /dev/tty
as O_PATH then no file-&gt;f_op-&gt;open() happens thus no file-&gt;f_owner is
allocated. That's fine as no file operation will be set for those and
the device has never been opened. fcntl()s called on such things will
just allocate a -&gt;f_owner on demand. Although I have zero idea why'd you
care about f_owner on an O_PATH fd.

Link: https://lore.kernel.org/r/20240813-work-f_owner-v2-1-4e9343a79f9f@kernel.org
Reviewed-by: Jeff Layton &lt;jlayton@kernel.org&gt;
Signed-off-by: Christian Brauner &lt;brauner@kernel.org&gt;
</content>
</entry>
<entry>
<title>tun: add missing verification for short frame</title>
<updated>2024-07-25T15:07:05+00:00</updated>
<author>
<name>Dongli Zhang</name>
<email>dongli.zhang@oracle.com</email>
</author>
<published>2024-07-24T17:04:52+00:00</published>
<link rel='alternate' type='text/html' href='https://git.radix-linux.su/kernel/linux.git/commit/?id=049584807f1d797fc3078b68035450a9769eb5c3'/>
<id>urn:sha1:049584807f1d797fc3078b68035450a9769eb5c3</id>
<content type='text'>
The cited commit missed to check against the validity of the frame length
in the tun_xdp_one() path, which could cause a corrupted skb to be sent
downstack. Even before the skb is transmitted, the
tun_xdp_one--&gt;eth_type_trans() may access the Ethernet header although it
can be less than ETH_HLEN. Once transmitted, this could either cause
out-of-bound access beyond the actual length, or confuse the underlayer
with incorrect or inconsistent header length in the skb metadata.

In the alternative path, tun_get_user() already prohibits short frame which
has the length less than Ethernet header size from being transmitted for
IFF_TAP.

This is to drop any frame shorter than the Ethernet header size just like
how tun_get_user() does.

CVE: CVE-2024-41091
Inspired-by: https://lore.kernel.org/netdev/1717026141-25716-1-git-send-email-si-wei.liu@oracle.com/
Fixes: 043d222f93ab ("tuntap: accept an array of XDP buffs through sendmsg()")
Cc: stable@vger.kernel.org
Signed-off-by: Dongli Zhang &lt;dongli.zhang@oracle.com&gt;
Reviewed-by: Si-Wei Liu &lt;si-wei.liu@oracle.com&gt;
Reviewed-by: Willem de Bruijn &lt;willemb@google.com&gt;
Reviewed-by: Paolo Abeni &lt;pabeni@redhat.com&gt;
Reviewed-by: Jason Wang &lt;jasowang@redhat.com&gt;
Link: https://patch.msgid.link/20240724170452.16837-3-dongli.zhang@oracle.com
Signed-off-by: Jakub Kicinski &lt;kuba@kernel.org&gt;
</content>
</entry>
</feed>
