<feed xmlns='http://www.w3.org/2005/Atom'>
<title>kernel/linux.git/include/linux, branch v6.1.124</title>
<subtitle>Linux kernel stable tree (mirror)</subtitle>
<id>https://git.radix-linux.su/kernel/linux.git/atom?h=v6.1.124</id>
<link rel='self' href='https://git.radix-linux.su/kernel/linux.git/atom?h=v6.1.124'/>
<link rel='alternate' type='text/html' href='https://git.radix-linux.su/kernel/linux.git/'/>
<updated>2025-01-09T12:30:02+00:00</updated>
<entry>
<title>af_packet: fix vlan_get_protocol_dgram() vs MSG_PEEK</title>
<updated>2025-01-09T12:30:02+00:00</updated>
<author>
<name>Eric Dumazet</name>
<email>edumazet@google.com</email>
</author>
<published>2024-12-30T16:10:04+00:00</published>
<link rel='alternate' type='text/html' href='https://git.radix-linux.su/kernel/linux.git/commit/?id=5d336714db324bef84490c75dcc48b387ef0346e'/>
<id>urn:sha1:5d336714db324bef84490c75dcc48b387ef0346e</id>
<content type='text'>
[ Upstream commit f91a5b8089389eb408501af2762f168c3aaa7b79 ]

Blamed commit forgot MSG_PEEK case, allowing a crash [1] as found
by syzbot.

Rework vlan_get_protocol_dgram() to not touch skb at all,
so that it can be used from many cpus on the same skb.

Add a const qualifier to skb argument.

[1]
skbuff: skb_under_panic: text:ffffffff8a8ccd05 len:29 put:14 head:ffff88807fc8e400 data:ffff88807fc8e3f4 tail:0x11 end:0x140 dev:&lt;NULL&gt;
------------[ cut here ]------------
 kernel BUG at net/core/skbuff.c:206 !
Oops: invalid opcode: 0000 [#1] PREEMPT SMP KASAN PTI
CPU: 1 UID: 0 PID: 5892 Comm: syz-executor883 Not tainted 6.13.0-rc4-syzkaller-00054-gd6ef8b40d075 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/13/2024
 RIP: 0010:skb_panic net/core/skbuff.c:206 [inline]
 RIP: 0010:skb_under_panic+0x14b/0x150 net/core/skbuff.c:216
Code: 0b 8d 48 c7 c6 86 d5 25 8e 48 8b 54 24 08 8b 0c 24 44 8b 44 24 04 4d 89 e9 50 41 54 41 57 41 56 e8 5a 69 79 f7 48 83 c4 20 90 &lt;0f&gt; 0b 0f 1f 00 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 f3
RSP: 0018:ffffc900038d7638 EFLAGS: 00010282
RAX: 0000000000000087 RBX: dffffc0000000000 RCX: 609ffd18ea660600
RDX: 0000000000000000 RSI: 0000000080000000 RDI: 0000000000000000
RBP: ffff88802483c8d0 R08: ffffffff817f0a8c R09: 1ffff9200071ae60
R10: dffffc0000000000 R11: fffff5200071ae61 R12: 0000000000000140
R13: ffff88807fc8e400 R14: ffff88807fc8e3f4 R15: 0000000000000011
FS:  00007fbac5e006c0(0000) GS:ffff8880b8700000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fbac5e00d58 CR3: 000000001238e000 CR4: 00000000003526f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 &lt;TASK&gt;
  skb_push+0xe5/0x100 net/core/skbuff.c:2636
  vlan_get_protocol_dgram+0x165/0x290 net/packet/af_packet.c:585
  packet_recvmsg+0x948/0x1ef0 net/packet/af_packet.c:3552
  sock_recvmsg_nosec net/socket.c:1033 [inline]
  sock_recvmsg+0x22f/0x280 net/socket.c:1055
  ____sys_recvmsg+0x1c6/0x480 net/socket.c:2803
  ___sys_recvmsg net/socket.c:2845 [inline]
  do_recvmmsg+0x426/0xab0 net/socket.c:2940
  __sys_recvmmsg net/socket.c:3014 [inline]
  __do_sys_recvmmsg net/socket.c:3037 [inline]
  __se_sys_recvmmsg net/socket.c:3030 [inline]
  __x64_sys_recvmmsg+0x199/0x250 net/socket.c:3030
  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: 79eecf631c14 ("af_packet: Handle outgoing VLAN packets without hardware offloading")
Reported-by: syzbot+74f70bb1cb968bf09e4f@syzkaller.appspotmail.com
Closes: https://lore.kernel.org/netdev/6772c485.050a0220.2f3838.04c5.GAE@google.com/T/#u
Signed-off-by: Eric Dumazet &lt;edumazet@google.com&gt;
Cc: Chengen Du &lt;chengen.du@canonical.com&gt;
Reviewed-by: Willem de Bruijn &lt;willemb@google.com&gt;
Link: https://patch.msgid.link/20241230161004.2681892-2-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>RDMA/mlx5: Enforce same type port association for multiport RoCE</title>
<updated>2025-01-09T12:29:57+00:00</updated>
<author>
<name>Patrisious Haddad</name>
<email>phaddad@nvidia.com</email>
</author>
<published>2024-12-03T13:45:37+00:00</published>
<link rel='alternate' type='text/html' href='https://git.radix-linux.su/kernel/linux.git/commit/?id=cbc35242a97a472ba8e3a87cac2ad861a4f9b164'/>
<id>urn:sha1:cbc35242a97a472ba8e3a87cac2ad861a4f9b164</id>
<content type='text'>
[ Upstream commit e05feab22fd7dabcd6d272c4e2401ec1acdfdb9b ]

Different core device types such as PFs and VFs shouldn't be affiliated
together since they have different capabilities, fix that by enforcing
type check before doing the affiliation.

Fixes: 32f69e4be269 ("{net, IB}/mlx5: Manage port association for multiport RoCE")
Reviewed-by: Mark Bloch &lt;mbloch@nvidia.com&gt;
Signed-off-by: Patrisious Haddad &lt;phaddad@nvidia.com&gt;
Link: https://patch.msgid.link/88699500f690dff1c1852c1ddb71f8a1cc8b956e.1733233480.git.leonro@nvidia.com
Reviewed-by: Mateusz Polchlopek &lt;mateusz.polchlopek@intel.com&gt;
Signed-off-by: Leon Romanovsky &lt;leon@kernel.org&gt;
Signed-off-by: Sasha Levin &lt;sashal@kernel.org&gt;
</content>
</entry>
<entry>
<title>tracing: Constify string literal data member in struct trace_event_call</title>
<updated>2025-01-02T09:30:54+00:00</updated>
<author>
<name>Christian Göttsche</name>
<email>cgzones@googlemail.com</email>
</author>
<published>2024-11-25T10:50:25+00:00</published>
<link rel='alternate' type='text/html' href='https://git.radix-linux.su/kernel/linux.git/commit/?id=f2a16d2ba4a6e7e68ac8910d5ab950d8e921ad6c'/>
<id>urn:sha1:f2a16d2ba4a6e7e68ac8910d5ab950d8e921ad6c</id>
<content type='text'>
commit 452f4b31e3f70a52b97890888eeb9eaa9a87139a upstream.

The name member of the struct trace_event_call is assigned with
generated string literals; declare them pointer to read-only.

Reported by clang:

    security/landlock/syscalls.c:179:1: warning: initializing 'char *' with an expression of type 'const char[34]' discards qualifiers [-Wincompatible-pointer-types-discards-qualifiers]
      179 | SYSCALL_DEFINE3(landlock_create_ruleset,
          | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
      180 |                 const struct landlock_ruleset_attr __user *const, attr,
          |                 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
      181 |                 const size_t, size, const __u32, flags)
          |                 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    ./include/linux/syscalls.h:226:36: note: expanded from macro 'SYSCALL_DEFINE3'
      226 | #define SYSCALL_DEFINE3(name, ...) SYSCALL_DEFINEx(3, _##name, __VA_ARGS__)
          |                                    ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    ./include/linux/syscalls.h:234:2: note: expanded from macro 'SYSCALL_DEFINEx'
      234 |         SYSCALL_METADATA(sname, x, __VA_ARGS__)                 \
          |         ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    ./include/linux/syscalls.h:184:2: note: expanded from macro 'SYSCALL_METADATA'
      184 |         SYSCALL_TRACE_ENTER_EVENT(sname);                       \
          |         ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    ./include/linux/syscalls.h:151:30: note: expanded from macro 'SYSCALL_TRACE_ENTER_EVENT'
      151 |                         .name                   = "sys_enter"#sname,    \
          |                                                   ^~~~~~~~~~~~~~~~~

Cc: stable@vger.kernel.org
Cc: Masami Hiramatsu &lt;mhiramat@kernel.org&gt;
Cc: Mathieu Desnoyers &lt;mathieu.desnoyers@efficios.com&gt;
Cc: Mickaël Salaün &lt;mic@digikod.net&gt;
Cc: Günther Noack &lt;gnoack@google.com&gt;
Cc: Nathan Chancellor &lt;nathan@kernel.org&gt;
Cc: Nick Desaulniers &lt;ndesaulniers@google.com&gt;
Cc: Bill Wendling &lt;morbo@google.com&gt;
Cc: Justin Stitt &lt;justinstitt@google.com&gt;
Link: https://lore.kernel.org/20241125105028.42807-1-cgoettsche@seltendoof.de
Fixes: b77e38aa240c3 ("tracing: add event trace infrastructure")
Signed-off-by: Christian Göttsche &lt;cgzones@googlemail.com&gt;
Signed-off-by: Steven Rostedt (Google) &lt;rostedt@goodmis.org&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;
</content>
</entry>
<entry>
<title>freezer, sched: Report frozen tasks as 'D' instead of 'R'</title>
<updated>2025-01-02T09:30:54+00:00</updated>
<author>
<name>Chen Ridong</name>
<email>chenridong@huawei.com</email>
</author>
<published>2024-12-17T00:48:18+00:00</published>
<link rel='alternate' type='text/html' href='https://git.radix-linux.su/kernel/linux.git/commit/?id=581d8a5ac119b0036836a9c69c0d68d939ec405b'/>
<id>urn:sha1:581d8a5ac119b0036836a9c69c0d68d939ec405b</id>
<content type='text'>
[ Upstream commit f718faf3940e95d5d34af9041f279f598396ab7d ]

Before commit:

  f5d39b020809 ("freezer,sched: Rewrite core freezer logic")

the frozen task stat was reported as 'D' in cgroup v1.

However, after rewriting the core freezer logic, the frozen task stat is
reported as 'R'. This is confusing, especially when a task with stat of
'S' is frozen.

This bug can be reproduced with these steps:

	$ cd /sys/fs/cgroup/freezer/
	$ mkdir test
	$ sleep 1000 &amp;
	[1] 739         // task whose stat is 'S'
	$ echo 739 &gt; test/cgroup.procs
	$ echo FROZEN &gt; test/freezer.state
	$ ps -aux | grep 739
	root     739  0.1  0.0   8376  1812 pts/0    R    10:56   0:00 sleep 1000

As shown above, a task whose stat is 'S' was changed to 'R' when it was
frozen.

To solve this regression, simply maintain the same reported state as
before the rewrite.

[ mingo: Enhanced the changelog and comments ]

Fixes: f5d39b020809 ("freezer,sched: Rewrite core freezer logic")
Signed-off-by: Chen Ridong &lt;chenridong@huawei.com&gt;
Signed-off-by: Peter Zijlstra (Intel) &lt;peterz@infradead.org&gt;
Signed-off-by: Ingo Molnar &lt;mingo@kernel.org&gt;
Acked-by: Tejun Heo &lt;tj@kernel.org&gt;
Acked-by: Michal Koutný &lt;mkoutny@suse.com&gt;
Link: https://lore.kernel.org/r/20241217004818.3200515-1-chenridong@huaweicloud.com
Signed-off-by: Sasha Levin &lt;sashal@kernel.org&gt;
</content>
</entry>
<entry>
<title>sched/core: Report correct state for TASK_IDLE | TASK_FREEZABLE</title>
<updated>2025-01-02T09:30:54+00:00</updated>
<author>
<name>NeilBrown</name>
<email>neilb@suse.de</email>
</author>
<published>2023-08-29T23:04:19+00:00</published>
<link rel='alternate' type='text/html' href='https://git.radix-linux.su/kernel/linux.git/commit/?id=b0ce4e8fedbd783b110693de311031d7ea04cdda'/>
<id>urn:sha1:b0ce4e8fedbd783b110693de311031d7ea04cdda</id>
<content type='text'>
[ Upstream commit 0d6b35283bcf1a379cf20066544af8e6a6b16b46 ]

task_state_index() ignores uninteresting state flags (such as
TASK_FREEZABLE) for most states, but for TASK_IDLE and TASK_RTLOCK_WAIT
it does not.

So if a task is waiting TASK_IDLE|TASK_FREEZABLE it gets incorrectly
reported as TASK_UNINTERRUPTIBLE or "D".  (it is planned for nfsd to
change to use this state).

Fix this by only testing the interesting bits and not the irrelevant
bits in __task_state_index()

Signed-off-by: NeilBrown &lt;neilb@suse.de&gt;
Signed-off-by: Ingo Molnar &lt;mingo@kernel.org&gt;
Link: https://lore.kernel.org/r/169335025927.5133.4781141800413736103@noble.neil.brown.name
Stable-dep-of: f718faf3940e ("freezer, sched: Report frozen tasks as 'D' instead of 'R'")
Signed-off-by: Sasha Levin &lt;sashal@kernel.org&gt;
</content>
</entry>
<entry>
<title>tcp_bpf: Add sk_rmem_alloc related logic for tcp_bpf ingress redirection</title>
<updated>2025-01-02T09:30:48+00:00</updated>
<author>
<name>Zijian Zhang</name>
<email>zijianzhang@bytedance.com</email>
</author>
<published>2024-12-10T01:20:39+00:00</published>
<link rel='alternate' type='text/html' href='https://git.radix-linux.su/kernel/linux.git/commit/?id=be848bde4a7ffa75a339bcead9265bc1b74b026a'/>
<id>urn:sha1:be848bde4a7ffa75a339bcead9265bc1b74b026a</id>
<content type='text'>
[ Upstream commit d888b7af7c149c115dd6ac772cc11c375da3e17c ]

When we do sk_psock_verdict_apply-&gt;sk_psock_skb_ingress, an sk_msg will
be created out of the skb, and the rmem accounting of the sk_msg will be
handled by the skb.

For skmsgs in __SK_REDIRECT case of tcp_bpf_send_verdict, when redirecting
to the ingress of a socket, although we sk_rmem_schedule and add sk_msg to
the ingress_msg of sk_redir, we do not update sk_rmem_alloc. As a result,
except for the global memory limit, the rmem of sk_redir is nearly
unlimited. Thus, add sk_rmem_alloc related logic to limit the recv buffer.

Since the function sk_msg_recvmsg and __sk_psock_purge_ingress_msg are
used in these two paths. We use "msg-&gt;skb" to test whether the sk_msg is
skb backed up. If it's not, we shall do the memory accounting explicitly.

Fixes: 604326b41a6f ("bpf, sockmap: convert to generic sk_msg interface")
Signed-off-by: Zijian Zhang &lt;zijianzhang@bytedance.com&gt;
Signed-off-by: Daniel Borkmann &lt;daniel@iogearbox.net&gt;
Reviewed-by: John Fastabend &lt;john.fastabend@gmail.com&gt;
Link: https://lore.kernel.org/bpf/20241210012039.1669389-3-zijianzhang@bytedance.com
Signed-off-by: Sasha Levin &lt;sashal@kernel.org&gt;
</content>
</entry>
<entry>
<title>mm/vmstat: fix a W=1 clang compiler warning</title>
<updated>2025-01-02T09:30:48+00:00</updated>
<author>
<name>Bart Van Assche</name>
<email>bvanassche@acm.org</email>
</author>
<published>2024-12-12T21:31:26+00:00</published>
<link rel='alternate' type='text/html' href='https://git.radix-linux.su/kernel/linux.git/commit/?id=b480e57d1389a040bfa08f0a634dac1b4db989e7'/>
<id>urn:sha1:b480e57d1389a040bfa08f0a634dac1b4db989e7</id>
<content type='text'>
[ Upstream commit 30c2de0a267c04046d89e678cc0067a9cfb455df ]

Fix the following clang compiler warning that is reported if the kernel is
built with W=1:

./include/linux/vmstat.h:518:36: error: arithmetic between different enumeration types ('enum node_stat_item' and 'enum lru_list') [-Werror,-Wenum-enum-conversion]
  518 |         return node_stat_name(NR_LRU_BASE + lru) + 3; // skip "nr_"
      |                               ~~~~~~~~~~~ ^ ~~~

Link: https://lkml.kernel.org/r/20241212213126.1269116-1-bvanassche@acm.org
Fixes: 9d7ea9a297e6 ("mm/vmstat: add helpers to get vmstat item names for each enum type")
Signed-off-by: Bart Van Assche &lt;bvanassche@acm.org&gt;
Cc: Konstantin Khlebnikov &lt;koct9i@gmail.com&gt;
Cc: Nathan Chancellor &lt;nathan@kernel.org&gt;
Signed-off-by: Andrew Morton &lt;akpm@linux-foundation.org&gt;
Signed-off-by: Sasha Levin &lt;sashal@kernel.org&gt;
</content>
</entry>
<entry>
<title>epoll: Add synchronous wakeup support for ep_poll_callback</title>
<updated>2024-12-27T12:53:01+00:00</updated>
<author>
<name>Xuewen Yan</name>
<email>xuewen.yan@unisoc.com</email>
</author>
<published>2024-04-26T08:05:48+00:00</published>
<link rel='alternate' type='text/html' href='https://git.radix-linux.su/kernel/linux.git/commit/?id=400a2ae671fa4a364bb40a2ff3ca468e2277b757'/>
<id>urn:sha1:400a2ae671fa4a364bb40a2ff3ca468e2277b757</id>
<content type='text'>
commit 900bbaae67e980945dec74d36f8afe0de7556d5a upstream.

Now, the epoll only use wake_up() interface to wake up task.
However, sometimes, there are epoll users which want to use
the synchronous wakeup flag to hint the scheduler, such as
Android binder driver.
So add a wake_up_sync() define, and use the wake_up_sync()
when the sync is true in ep_poll_callback().

Co-developed-by: Jing Xia &lt;jing.xia@unisoc.com&gt;
Signed-off-by: Jing Xia &lt;jing.xia@unisoc.com&gt;
Signed-off-by: Xuewen Yan &lt;xuewen.yan@unisoc.com&gt;
Link: https://lore.kernel.org/r/20240426080548.8203-1-xuewen.yan@unisoc.com
Tested-by: Brian Geffon &lt;bgeffon@google.com&gt;
Reviewed-by: Brian Geffon &lt;bgeffon@google.com&gt;
Reported-by: Benoit Lize &lt;lizeb@google.com&gt;
Signed-off-by: Christian Brauner &lt;brauner@kernel.org&gt;
Cc: Brian Geffon &lt;bgeffon@google.com&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;
</content>
</entry>
<entry>
<title>io_uring: Fix registered ring file refcount leak</title>
<updated>2024-12-27T12:53:00+00:00</updated>
<author>
<name>Jann Horn</name>
<email>jannh@google.com</email>
</author>
<published>2024-12-18T16:56:25+00:00</published>
<link rel='alternate' type='text/html' href='https://git.radix-linux.su/kernel/linux.git/commit/?id=c034ce2668ae94f04ff46d29b195409614feaf75'/>
<id>urn:sha1:c034ce2668ae94f04ff46d29b195409614feaf75</id>
<content type='text'>
commit 12d908116f7efd34f255a482b9afc729d7a5fb78 upstream.

Currently, io_uring_unreg_ringfd() (which cleans up registered rings) is
only called on exit, but __io_uring_free (which frees the tctx in which the
registered ring pointers are stored) is also called on execve (via
begin_new_exec -&gt; io_uring_task_cancel -&gt; __io_uring_cancel -&gt;
io_uring_cancel_generic -&gt; __io_uring_free).

This means: A process going through execve while having registered rings
will leak references to the rings' `struct file`.

Fix it by zapping registered rings on execve(). This is implemented by
moving the io_uring_unreg_ringfd() from io_uring_files_cancel() into its
callee __io_uring_cancel(), which is called from io_uring_task_cancel() on
execve.

This could probably be exploited *on 32-bit kernels* by leaking 2^32
references to the same ring, because the file refcount is stored in a
pointer-sized field and get_file() doesn't have protection against
refcount overflow, just a WARN_ONCE(); but on 64-bit it should have no
impact beyond a memory leak.

Cc: stable@vger.kernel.org
Fixes: e7a6c00dc77a ("io_uring: add support for registering ring file descriptors")
Signed-off-by: Jann Horn &lt;jannh@google.com&gt;
Link: https://lore.kernel.org/r/20241218-uring-reg-ring-cleanup-v1-1-8f63e999045b@google.com
Signed-off-by: Jens Axboe &lt;axboe@kernel.dk&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;
</content>
</entry>
<entry>
<title>Drivers: hv: util: Avoid accessing a ringbuffer not initialized yet</title>
<updated>2024-12-27T12:52:59+00:00</updated>
<author>
<name>Michael Kelley</name>
<email>mhklinux@outlook.com</email>
</author>
<published>2024-11-06T15:42:47+00:00</published>
<link rel='alternate' type='text/html' href='https://git.radix-linux.su/kernel/linux.git/commit/?id=718fe694a334be9d1a89eed22602369ac18d6583'/>
<id>urn:sha1:718fe694a334be9d1a89eed22602369ac18d6583</id>
<content type='text'>
commit 07a756a49f4b4290b49ea46e089cbe6f79ff8d26 upstream.

If the KVP (or VSS) daemon starts before the VMBus channel's ringbuffer is
fully initialized, we can hit the panic below:

hv_utils: Registering HyperV Utility Driver
hv_vmbus: registering driver hv_utils
...
BUG: kernel NULL pointer dereference, address: 0000000000000000
CPU: 44 UID: 0 PID: 2552 Comm: hv_kvp_daemon Tainted: G E 6.11.0-rc3+ #1
RIP: 0010:hv_pkt_iter_first+0x12/0xd0
Call Trace:
...
 vmbus_recvpacket
 hv_kvp_onchannelcallback
 vmbus_on_event
 tasklet_action_common
 tasklet_action
 handle_softirqs
 irq_exit_rcu
 sysvec_hyperv_stimer0
 &lt;/IRQ&gt;
 &lt;TASK&gt;
 asm_sysvec_hyperv_stimer0
...
 kvp_register_done
 hvt_op_read
 vfs_read
 ksys_read
 __x64_sys_read

This can happen because the KVP/VSS channel callback can be invoked
even before the channel is fully opened:
1) as soon as hv_kvp_init() -&gt; hvutil_transport_init() creates
/dev/vmbus/hv_kvp, the kvp daemon can open the device file immediately and
register itself to the driver by writing a message KVP_OP_REGISTER1 to the
file (which is handled by kvp_on_msg() -&gt;kvp_handle_handshake()) and
reading the file for the driver's response, which is handled by
hvt_op_read(), which calls hvt-&gt;on_read(), i.e. kvp_register_done().

2) the problem with kvp_register_done() is that it can cause the
channel callback to be called even before the channel is fully opened,
and when the channel callback is starting to run, util_probe()-&gt;
vmbus_open() may have not initialized the ringbuffer yet, so the
callback can hit the panic of NULL pointer dereference.

To reproduce the panic consistently, we can add a "ssleep(10)" for KVP in
__vmbus_open(), just before the first hv_ringbuffer_init(), and then we
unload and reload the driver hv_utils, and run the daemon manually within
the 10 seconds.

Fix the panic by reordering the steps in util_probe() so the char dev
entry used by the KVP or VSS daemon is not created until after
vmbus_open() has completed. This reordering prevents the race condition
from happening.

Reported-by: Dexuan Cui &lt;decui@microsoft.com&gt;
Fixes: e0fa3e5e7df6 ("Drivers: hv: utils: fix a race on userspace daemons registration")
Cc: stable@vger.kernel.org
Signed-off-by: Michael Kelley &lt;mhklinux@outlook.com&gt;
Acked-by: Wei Liu &lt;wei.liu@kernel.org&gt;
Link: https://lore.kernel.org/r/20241106154247.2271-3-mhklinux@outlook.com
Signed-off-by: Wei Liu &lt;wei.liu@kernel.org&gt;
Message-ID: &lt;20241106154247.2271-3-mhklinux@outlook.com&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;
</content>
</entry>
</feed>
