<feed xmlns='http://www.w3.org/2005/Atom'>
<title>kernel/linux.git/include, branch v4.14.161</title>
<subtitle>Linux kernel stable tree (mirror)</subtitle>
<id>https://git.radix-linux.su/kernel/linux.git/atom?h=v4.14.161</id>
<link rel='self' href='https://git.radix-linux.su/kernel/linux.git/atom?h=v4.14.161'/>
<link rel='alternate' type='text/html' href='https://git.radix-linux.su/kernel/linux.git/'/>
<updated>2019-12-31T11:37:21+00:00</updated>
<entry>
<title>rfkill: allocate static minor</title>
<updated>2019-12-31T11:37:21+00:00</updated>
<author>
<name>Marcel Holtmann</name>
<email>marcel@holtmann.org</email>
</author>
<published>2019-10-24T17:40:42+00:00</published>
<link rel='alternate' type='text/html' href='https://git.radix-linux.su/kernel/linux.git/commit/?id=b7a6c8ec56d804daa10879fce35843fe84da0ea4'/>
<id>urn:sha1:b7a6c8ec56d804daa10879fce35843fe84da0ea4</id>
<content type='text'>
[ Upstream commit 8670b2b8b029a6650d133486be9d2ace146fd29a ]

udev has a feature of creating /dev/&lt;node&gt; device-nodes if it finds
a devnode:&lt;node&gt; modalias. This allows for auto-loading of modules that
provide the node. This requires to use a statically allocated minor
number for misc character devices.

However, rfkill uses dynamic minor numbers and prevents auto-loading
of the module. So allocate the next static misc minor number and use
it for rfkill.

Signed-off-by: Marcel Holtmann &lt;marcel@holtmann.org&gt;
Link: https://lore.kernel.org/r/20191024174042.19851-1-marcel@holtmann.org
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;
Signed-off-by: Sasha Levin &lt;sashal@kernel.org&gt;
</content>
</entry>
<entry>
<title>block: Fix writeback throttling W=1 compiler warnings</title>
<updated>2019-12-31T11:37:01+00:00</updated>
<author>
<name>Bart Van Assche</name>
<email>bvanassche@acm.org</email>
</author>
<published>2019-09-30T23:00:41+00:00</published>
<link rel='alternate' type='text/html' href='https://git.radix-linux.su/kernel/linux.git/commit/?id=8e1823f13a0f3c8635c64c789f9804316ad8934d'/>
<id>urn:sha1:8e1823f13a0f3c8635c64c789f9804316ad8934d</id>
<content type='text'>
[ Upstream commit 1d200e9d6f635ae894993a7d0f1b9e0b6e522e3b ]

Fix the following compiler warnings:

In file included from ./include/linux/bitmap.h:9,
                 from ./include/linux/cpumask.h:12,
                 from ./arch/x86/include/asm/cpumask.h:5,
                 from ./arch/x86/include/asm/msr.h:11,
                 from ./arch/x86/include/asm/processor.h:21,
                 from ./arch/x86/include/asm/cpufeature.h:5,
                 from ./arch/x86/include/asm/thread_info.h:53,
                 from ./include/linux/thread_info.h:38,
                 from ./arch/x86/include/asm/preempt.h:7,
                 from ./include/linux/preempt.h:78,
                 from ./include/linux/spinlock.h:51,
                 from ./include/linux/mmzone.h:8,
                 from ./include/linux/gfp.h:6,
                 from ./include/linux/mm.h:10,
                 from ./include/linux/bvec.h:13,
                 from ./include/linux/blk_types.h:10,
                 from block/blk-wbt.c:23:
In function 'strncpy',
    inlined from 'perf_trace_wbt_stat' at ./include/trace/events/wbt.h:15:1:
./include/linux/string.h:260:9: warning: '__builtin_strncpy' specified bound 32 equals destination size [-Wstringop-truncation]
  return __builtin_strncpy(p, q, size);
         ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~
In function 'strncpy',
    inlined from 'perf_trace_wbt_lat' at ./include/trace/events/wbt.h:58:1:
./include/linux/string.h:260:9: warning: '__builtin_strncpy' specified bound 32 equals destination size [-Wstringop-truncation]
  return __builtin_strncpy(p, q, size);
         ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~
In function 'strncpy',
    inlined from 'perf_trace_wbt_step' at ./include/trace/events/wbt.h:87:1:
./include/linux/string.h:260:9: warning: '__builtin_strncpy' specified bound 32 equals destination size [-Wstringop-truncation]
  return __builtin_strncpy(p, q, size);
         ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~
In function 'strncpy',
    inlined from 'perf_trace_wbt_timer' at ./include/trace/events/wbt.h:126:1:
./include/linux/string.h:260:9: warning: '__builtin_strncpy' specified bound 32 equals destination size [-Wstringop-truncation]
  return __builtin_strncpy(p, q, size);
         ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~
In function 'strncpy',
    inlined from 'trace_event_raw_event_wbt_stat' at ./include/trace/events/wbt.h:15:1:
./include/linux/string.h:260:9: warning: '__builtin_strncpy' specified bound 32 equals destination size [-Wstringop-truncation]
  return __builtin_strncpy(p, q, size);
         ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~
In function 'strncpy',
    inlined from 'trace_event_raw_event_wbt_lat' at ./include/trace/events/wbt.h:58:1:
./include/linux/string.h:260:9: warning: '__builtin_strncpy' specified bound 32 equals destination size [-Wstringop-truncation]
  return __builtin_strncpy(p, q, size);
         ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~
In function 'strncpy',
    inlined from 'trace_event_raw_event_wbt_timer' at ./include/trace/events/wbt.h:126:1:
./include/linux/string.h:260:9: warning: '__builtin_strncpy' specified bound 32 equals destination size [-Wstringop-truncation]
  return __builtin_strncpy(p, q, size);
         ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~
In function 'strncpy',
    inlined from 'trace_event_raw_event_wbt_step' at ./include/trace/events/wbt.h:87:1:
./include/linux/string.h:260:9: warning: '__builtin_strncpy' specified bound 32 equals destination size [-Wstringop-truncation]
  return __builtin_strncpy(p, q, size);
         ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Cc: Christoph Hellwig &lt;hch@infradead.org&gt;
Cc: Ming Lei &lt;ming.lei@redhat.com&gt;
Cc: Hannes Reinecke &lt;hare@suse.com&gt;
Cc: Johannes Thumshirn &lt;jthumshirn@suse.de&gt;
Fixes: e34cbd307477 ("blk-wbt: add general throttling mechanism"; v4.10).
Signed-off-by: Bart Van Assche &lt;bvanassche@acm.org&gt;
Signed-off-by: Jens Axboe &lt;axboe@kernel.dk&gt;
Signed-off-by: Sasha Levin &lt;sashal@kernel.org&gt;
</content>
</entry>
<entry>
<title>media: cec-funcs.h: add status_req checks</title>
<updated>2019-12-31T11:36:59+00:00</updated>
<author>
<name>Hans Verkuil</name>
<email>hverkuil-cisco@xs4all.nl</email>
</author>
<published>2019-10-01T07:56:38+00:00</published>
<link rel='alternate' type='text/html' href='https://git.radix-linux.su/kernel/linux.git/commit/?id=9068d32b52425d2ac2031e69a42f7d3cf3912030'/>
<id>urn:sha1:9068d32b52425d2ac2031e69a42f7d3cf3912030</id>
<content type='text'>
[ Upstream commit 9b211f9c5a0b67afc435b86f75d78273b97db1c5 ]

The CEC_MSG_GIVE_DECK_STATUS and CEC_MSG_GIVE_TUNER_DEVICE_STATUS commands
both have a status_req argument: ON, OFF, ONCE. If ON or ONCE, then the
follower will reply with a STATUS message. Either once or whenever the
status changes (status_req == ON).

If status_req == OFF, then it will stop sending continuous status updates,
but the follower will *not* send a STATUS message in that case.

This means that if status_req == OFF, then msg-&gt;reply should be 0 as well
since no reply is expected in that case.

Signed-off-by: Hans Verkuil &lt;hverkuil-cisco@xs4all.nl&gt;
Signed-off-by: Mauro Carvalho Chehab &lt;mchehab+samsung@kernel.org&gt;
Signed-off-by: Sasha Levin &lt;sashal@kernel.org&gt;
</content>
</entry>
<entry>
<title>drm: mst: Fix query_payload ack reply struct</title>
<updated>2019-12-31T11:36:46+00:00</updated>
<author>
<name>Sean Paul</name>
<email>seanpaul@chromium.org</email>
</author>
<published>2019-08-29T16:52:19+00:00</published>
<link rel='alternate' type='text/html' href='https://git.radix-linux.su/kernel/linux.git/commit/?id=80eb7d92e253a83f090dd927b3d653de0ce7ceb6'/>
<id>urn:sha1:80eb7d92e253a83f090dd927b3d653de0ce7ceb6</id>
<content type='text'>
[ Upstream commit 268de6530aa18fe5773062367fd119f0045f6e88 ]

Spec says[1] Allocated_PBN is 16 bits

[1]- DisplayPort 1.2 Spec, Section 2.11.9.8, Table 2-98

Fixes: ad7f8a1f9ced ("drm/helper: add Displayport multi-stream helper (v0.6)")
Cc: Lyude Paul &lt;lyude@redhat.com&gt;
Cc: Todd Previte &lt;tprevite@gmail.com&gt;
Cc: Dave Airlie &lt;airlied@redhat.com&gt;
Cc: Maarten Lankhorst &lt;maarten.lankhorst@linux.intel.com&gt;
Cc: Maxime Ripard &lt;maxime.ripard@bootlin.com&gt;
Cc: Sean Paul &lt;sean@poorly.run&gt;
Cc: David Airlie &lt;airlied@linux.ie&gt;
Cc: Daniel Vetter &lt;daniel@ffwll.ch&gt;
Cc: dri-devel@lists.freedesktop.org
Reviewed-by: Lyude Paul &lt;lyude@redhat.com&gt;
Signed-off-by: Sean Paul &lt;seanpaul@chromium.org&gt;
Link: https://patchwork.freedesktop.org/patch/msgid/20190829165223.129662-1-sean@poorly.run
Signed-off-by: Sasha Levin &lt;sashal@kernel.org&gt;
</content>
</entry>
<entry>
<title>net: dst: Force 4-byte alignment of dst_metrics</title>
<updated>2019-12-31T11:36:40+00:00</updated>
<author>
<name>Geert Uytterhoeven</name>
<email>geert@linux-m68k.org</email>
</author>
<published>2019-12-20T13:31:40+00:00</published>
<link rel='alternate' type='text/html' href='https://git.radix-linux.su/kernel/linux.git/commit/?id=b1990ae775117fc4311c8cacea12f3c4d9481a97'/>
<id>urn:sha1:b1990ae775117fc4311c8cacea12f3c4d9481a97</id>
<content type='text'>
[ Upstream commit 258a980d1ec23e2c786e9536a7dd260bea74bae6 ]

When storing a pointer to a dst_metrics structure in dst_entry._metrics,
two flags are added in the least significant bits of the pointer value.
Hence this assumes all pointers to dst_metrics structures have at least
4-byte alignment.

However, on m68k, the minimum alignment of 32-bit values is 2 bytes, not
4 bytes.  Hence in some kernel builds, dst_default_metrics may be only
2-byte aligned, leading to obscure boot warnings like:

    WARNING: CPU: 0 PID: 7 at lib/refcount.c:28 refcount_warn_saturate+0x44/0x9a
    refcount_t: underflow; use-after-free.
    Modules linked in:
    CPU: 0 PID: 7 Comm: ksoftirqd/0 Tainted: G        W         5.5.0-rc2-atari-01448-g114a1a1038af891d-dirty #261
    Stack from 10835e6c:
	    10835e6c 0038134f 00023fa6 00394b0f 0000001c 00000009 00321560 00023fea
	    00394b0f 0000001c 001a70f8 00000009 00000000 10835eb4 00000001 00000000
	    04208040 0000000a 00394b4a 10835ed4 00043aa8 001a70f8 00394b0f 0000001c
	    00000009 00394b4a 0026aba8 003215a4 00000003 00000000 0026d5a8 00000001
	    003215a4 003a4361 003238d6 000001f0 00000000 003215a4 10aa3b00 00025e84
	    003ddb00 10834000 002416a8 10aa3b00 00000000 00000080 000aa038 0004854a
    Call Trace: [&lt;00023fa6&gt;] __warn+0xb2/0xb4
     [&lt;00023fea&gt;] warn_slowpath_fmt+0x42/0x64
     [&lt;001a70f8&gt;] refcount_warn_saturate+0x44/0x9a
     [&lt;00043aa8&gt;] printk+0x0/0x18
     [&lt;001a70f8&gt;] refcount_warn_saturate+0x44/0x9a
     [&lt;0026aba8&gt;] refcount_sub_and_test.constprop.73+0x38/0x3e
     [&lt;0026d5a8&gt;] ipv4_dst_destroy+0x5e/0x7e
     [&lt;00025e84&gt;] __local_bh_enable_ip+0x0/0x8e
     [&lt;002416a8&gt;] dst_destroy+0x40/0xae

Fix this by forcing 4-byte alignment of all dst_metrics structures.

Fixes: e5fd387ad5b30ca3 ("ipv6: do not overwrite inetpeer metrics prematurely")
Signed-off-by: Geert Uytterhoeven &lt;geert@linux-m68k.org&gt;
Signed-off-by: David S. Miller &lt;davem@davemloft.net&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;
</content>
</entry>
<entry>
<title>mod_devicetable: fix PHY module format</title>
<updated>2019-12-31T11:36:40+00:00</updated>
<author>
<name>Russell King</name>
<email>rmk+kernel@armlinux.org.uk</email>
</author>
<published>2019-12-19T23:24:47+00:00</published>
<link rel='alternate' type='text/html' href='https://git.radix-linux.su/kernel/linux.git/commit/?id=ab8224804954d8d32b46805db5e662f174fd5e10'/>
<id>urn:sha1:ab8224804954d8d32b46805db5e662f174fd5e10</id>
<content type='text'>
[ Upstream commit d2ed49cf6c13e379c5819aa5ac20e1f9674ebc89 ]

When a PHY is probed, if the top bit is set, we end up requesting a
module with the string "mdio:-10101110000000100101000101010001" -
the top bit is printed to a signed -1 value. This leads to the module
not being loaded.

Fix the module format string and the macro generating the values for
it to ensure that we only print unsigned types and the top bit is
always 0/1. We correctly end up with
"mdio:10101110000000100101000101010001".

Fixes: 8626d3b43280 ("phylib: Support phy module autoloading")
Reviewed-by: Andrew Lunn &lt;andrew@lunn.ch&gt;
Signed-off-by: Russell King &lt;rmk+kernel@armlinux.org.uk&gt;
Reviewed-by: Florian Fainelli &lt;f.fainelli@gmail.com&gt;
Signed-off-by: David S. Miller &lt;davem@davemloft.net&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;
</content>
</entry>
<entry>
<title>inet: protect against too small mtu values.</title>
<updated>2019-12-21T09:47:38+00:00</updated>
<author>
<name>Eric Dumazet</name>
<email>edumazet@google.com</email>
</author>
<published>2019-12-06T04:43:46+00:00</published>
<link rel='alternate' type='text/html' href='https://git.radix-linux.su/kernel/linux.git/commit/?id=7272e8e3bfa354a4f2c829a80180f01dc66d4861'/>
<id>urn:sha1:7272e8e3bfa354a4f2c829a80180f01dc66d4861</id>
<content type='text'>
[ Upstream commit 501a90c945103e8627406763dac418f20f3837b2 ]

syzbot was once again able to crash a host by setting a very small mtu
on loopback device.

Let's make inetdev_valid_mtu() available in include/net/ip.h,
and use it in ip_setup_cork(), so that we protect both ip_append_page()
and __ip_append_data()

Also add a READ_ONCE() when the device mtu is read.

Pairs this lockless read with one WRITE_ONCE() in __dev_set_mtu(),
even if other code paths might write over this field.

Add a big comment in include/linux/netdevice.h about dev-&gt;mtu
needing READ_ONCE()/WRITE_ONCE() annotations.

Hopefully we will add the missing ones in followup patches.

[1]

refcount_t: saturated; leaking memory.
WARNING: CPU: 0 PID: 9464 at lib/refcount.c:22 refcount_warn_saturate+0x138/0x1f0 lib/refcount.c:22
Kernel panic - not syncing: panic_on_warn set ...
CPU: 0 PID: 9464 Comm: syz-executor850 Not tainted 5.4.0-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
 __dump_stack lib/dump_stack.c:77 [inline]
 dump_stack+0x197/0x210 lib/dump_stack.c:118
 panic+0x2e3/0x75c kernel/panic.c:221
 __warn.cold+0x2f/0x3e kernel/panic.c:582
 report_bug+0x289/0x300 lib/bug.c:195
 fixup_bug arch/x86/kernel/traps.c:174 [inline]
 fixup_bug arch/x86/kernel/traps.c:169 [inline]
 do_error_trap+0x11b/0x200 arch/x86/kernel/traps.c:267
 do_invalid_op+0x37/0x50 arch/x86/kernel/traps.c:286
 invalid_op+0x23/0x30 arch/x86/entry/entry_64.S:1027
RIP: 0010:refcount_warn_saturate+0x138/0x1f0 lib/refcount.c:22
Code: 06 31 ff 89 de e8 c8 f5 e6 fd 84 db 0f 85 6f ff ff ff e8 7b f4 e6 fd 48 c7 c7 e0 71 4f 88 c6 05 56 a6 a4 06 01 e8 c7 a8 b7 fd &lt;0f&gt; 0b e9 50 ff ff ff e8 5c f4 e6 fd 0f b6 1d 3d a6 a4 06 31 ff 89
RSP: 0018:ffff88809689f550 EFLAGS: 00010286
RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000000000000
RDX: 0000000000000000 RSI: ffffffff815e4336 RDI: ffffed1012d13e9c
RBP: ffff88809689f560 R08: ffff88809c50a3c0 R09: fffffbfff15d31b1
R10: fffffbfff15d31b0 R11: ffffffff8ae98d87 R12: 0000000000000001
R13: 0000000000040100 R14: ffff888099041104 R15: ffff888218d96e40
 refcount_add include/linux/refcount.h:193 [inline]
 skb_set_owner_w+0x2b6/0x410 net/core/sock.c:1999
 sock_wmalloc+0xf1/0x120 net/core/sock.c:2096
 ip_append_page+0x7ef/0x1190 net/ipv4/ip_output.c:1383
 udp_sendpage+0x1c7/0x480 net/ipv4/udp.c:1276
 inet_sendpage+0xdb/0x150 net/ipv4/af_inet.c:821
 kernel_sendpage+0x92/0xf0 net/socket.c:3794
 sock_sendpage+0x8b/0xc0 net/socket.c:936
 pipe_to_sendpage+0x2da/0x3c0 fs/splice.c:458
 splice_from_pipe_feed fs/splice.c:512 [inline]
 __splice_from_pipe+0x3ee/0x7c0 fs/splice.c:636
 splice_from_pipe+0x108/0x170 fs/splice.c:671
 generic_splice_sendpage+0x3c/0x50 fs/splice.c:842
 do_splice_from fs/splice.c:861 [inline]
 direct_splice_actor+0x123/0x190 fs/splice.c:1035
 splice_direct_to_actor+0x3b4/0xa30 fs/splice.c:990
 do_splice_direct+0x1da/0x2a0 fs/splice.c:1078
 do_sendfile+0x597/0xd00 fs/read_write.c:1464
 __do_sys_sendfile64 fs/read_write.c:1525 [inline]
 __se_sys_sendfile64 fs/read_write.c:1511 [inline]
 __x64_sys_sendfile64+0x1dd/0x220 fs/read_write.c:1511
 do_syscall_64+0xfa/0x790 arch/x86/entry/common.c:294
 entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x441409
Code: e8 ac e8 ff ff 48 83 c4 18 c3 0f 1f 80 00 00 00 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 &lt;48&gt; 3d 01 f0 ff ff 0f 83 eb 08 fc ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007fffb64c4f78 EFLAGS: 00000246 ORIG_RAX: 0000000000000028
RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 0000000000441409
RDX: 0000000000000000 RSI: 0000000000000006 RDI: 0000000000000005
RBP: 0000000000073b8a R08: 0000000000000010 R09: 0000000000000010
R10: 0000000000010001 R11: 0000000000000246 R12: 0000000000402180
R13: 0000000000402210 R14: 0000000000000000 R15: 0000000000000000
Kernel Offset: disabled
Rebooting in 86400 seconds..

Fixes: 1470ddf7f8ce ("inet: Remove explicit write references to sk/inet in ip_append_data")
Signed-off-by: Eric Dumazet &lt;edumazet@google.com&gt;
Reported-by: syzbot &lt;syzkaller@googlegroups.com&gt;
Signed-off-by: David S. Miller &lt;davem@davemloft.net&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;
</content>
</entry>
<entry>
<title>tcp: Protect accesses to .ts_recent_stamp with {READ,WRITE}_ONCE()</title>
<updated>2019-12-21T09:47:37+00:00</updated>
<author>
<name>Guillaume Nault</name>
<email>gnault@redhat.com</email>
</author>
<published>2019-12-06T11:38:49+00:00</published>
<link rel='alternate' type='text/html' href='https://git.radix-linux.su/kernel/linux.git/commit/?id=b8a30668954f72174bb5cd007be9351bbe31f726'/>
<id>urn:sha1:b8a30668954f72174bb5cd007be9351bbe31f726</id>
<content type='text'>
[ Upstream commit 721c8dafad26ccfa90ff659ee19755e3377b829d ]

Syncookies borrow the -&gt;rx_opt.ts_recent_stamp field to store the
timestamp of the last synflood. Protect them with READ_ONCE() and
WRITE_ONCE() since reads and writes aren't serialised.

Use of .rx_opt.ts_recent_stamp for storing the synflood timestamp was
introduced by a0f82f64e269 ("syncookies: remove last_synq_overflow from
struct tcp_sock"). But unprotected accesses were already there when
timestamp was stored in .last_synq_overflow.

Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
Signed-off-by: Guillaume Nault &lt;gnault@redhat.com&gt;
Signed-off-by: Eric Dumazet &lt;edumazet@google.com&gt;
Signed-off-by: David S. Miller &lt;davem@davemloft.net&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;
</content>
</entry>
<entry>
<title>tcp: tighten acceptance of ACKs not matching a child socket</title>
<updated>2019-12-21T09:47:37+00:00</updated>
<author>
<name>Guillaume Nault</name>
<email>gnault@redhat.com</email>
</author>
<published>2019-12-06T11:38:43+00:00</published>
<link rel='alternate' type='text/html' href='https://git.radix-linux.su/kernel/linux.git/commit/?id=12f1107bd7fdb15f144575ce391e7571db8098bf'/>
<id>urn:sha1:12f1107bd7fdb15f144575ce391e7571db8098bf</id>
<content type='text'>
[ Upstream commit cb44a08f8647fd2e8db5cc9ac27cd8355fa392d8 ]

When no synflood occurs, the synflood timestamp isn't updated.
Therefore it can be so old that time_after32() can consider it to be
in the future.

That's a problem for tcp_synq_no_recent_overflow() as it may report
that a recent overflow occurred while, in fact, it's just that jiffies
has grown past 'last_overflow' + TCP_SYNCOOKIE_VALID + 2^31.

Spurious detection of recent overflows lead to extra syncookie
verification in cookie_v[46]_check(). At that point, the verification
should fail and the packet dropped. But we should have dropped the
packet earlier as we didn't even send a syncookie.

Let's refine tcp_synq_no_recent_overflow() to report a recent overflow
only if jiffies is within the
[last_overflow, last_overflow + TCP_SYNCOOKIE_VALID] interval. This
way, no spurious recent overflow is reported when jiffies wraps and
'last_overflow' becomes in the future from the point of view of
time_after32().

However, if jiffies wraps and enters the
[last_overflow, last_overflow + TCP_SYNCOOKIE_VALID] interval (with
'last_overflow' being a stale synflood timestamp), then
tcp_synq_no_recent_overflow() still erroneously reports an
overflow. In such cases, we have to rely on syncookie verification
to drop the packet. We unfortunately have no way to differentiate
between a fresh and a stale syncookie timestamp.

In practice, using last_overflow as lower bound is problematic.
If the synflood timestamp is concurrently updated between the time
we read jiffies and the moment we store the timestamp in
'last_overflow', then 'now' becomes smaller than 'last_overflow' and
tcp_synq_no_recent_overflow() returns true, potentially dropping a
valid syncookie.

Reading jiffies after loading the timestamp could fix the problem,
but that'd require a memory barrier. Let's just accommodate for
potential timestamp growth instead and extend the interval using
'last_overflow - HZ' as lower bound.

Signed-off-by: Guillaume Nault &lt;gnault@redhat.com&gt;
Signed-off-by: Eric Dumazet &lt;edumazet@google.com&gt;
Signed-off-by: David S. Miller &lt;davem@davemloft.net&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;
</content>
</entry>
<entry>
<title>tcp: fix rejected syncookies due to stale timestamps</title>
<updated>2019-12-21T09:47:36+00:00</updated>
<author>
<name>Guillaume Nault</name>
<email>gnault@redhat.com</email>
</author>
<published>2019-12-06T11:38:36+00:00</published>
<link rel='alternate' type='text/html' href='https://git.radix-linux.su/kernel/linux.git/commit/?id=9a8f9033dde9094f069af6d1b4e0c753b40b5dc4'/>
<id>urn:sha1:9a8f9033dde9094f069af6d1b4e0c753b40b5dc4</id>
<content type='text'>
[ Upstream commit 04d26e7b159a396372646a480f4caa166d1b6720 ]

If no synflood happens for a long enough period of time, then the
synflood timestamp isn't refreshed and jiffies can advance so much
that time_after32() can't accurately compare them any more.

Therefore, we can end up in a situation where time_after32(now,
last_overflow + HZ) returns false, just because these two values are
too far apart. In that case, the synflood timestamp isn't updated as
it should be, which can trick tcp_synq_no_recent_overflow() into
rejecting valid syncookies.

For example, let's consider the following scenario on a system
with HZ=1000:

  * The synflood timestamp is 0, either because that's the timestamp
    of the last synflood or, more commonly, because we're working with
    a freshly created socket.

  * We receive a new SYN, which triggers synflood protection. Let's say
    that this happens when jiffies == 2147484649 (that is,
    'synflood timestamp' + HZ + 2^31 + 1).

  * Then tcp_synq_overflow() doesn't update the synflood timestamp,
    because time_after32(2147484649, 1000) returns false.
    With:
      - 2147484649: the value of jiffies, aka. 'now'.
      - 1000: the value of 'last_overflow' + HZ.

  * A bit later, we receive the ACK completing the 3WHS. But
    cookie_v[46]_check() rejects it because tcp_synq_no_recent_overflow()
    says that we're not under synflood. That's because
    time_after32(2147484649, 120000) returns false.
    With:
      - 2147484649: the value of jiffies, aka. 'now'.
      - 120000: the value of 'last_overflow' + TCP_SYNCOOKIE_VALID.

    Of course, in reality jiffies would have increased a bit, but this
    condition will last for the next 119 seconds, which is far enough
    to accommodate for jiffie's growth.

Fix this by updating the overflow timestamp whenever jiffies isn't
within the [last_overflow, last_overflow + HZ] range. That shouldn't
have any performance impact since the update still happens at most once
per second.

Now we're guaranteed to have fresh timestamps while under synflood, so
tcp_synq_no_recent_overflow() can safely use it with time_after32() in
such situations.

Stale timestamps can still make tcp_synq_no_recent_overflow() return
the wrong verdict when not under synflood. This will be handled in the
next patch.

For 64 bits architectures, the problem was introduced with the
conversion of -&gt;tw_ts_recent_stamp to 32 bits integer by commit
cca9bab1b72c ("tcp: use monotonic timestamps for PAWS").
The problem has always been there on 32 bits architectures.

Fixes: cca9bab1b72c ("tcp: use monotonic timestamps for PAWS")
Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
Signed-off-by: Guillaume Nault &lt;gnault@redhat.com&gt;
Signed-off-by: Eric Dumazet &lt;edumazet@google.com&gt;
Signed-off-by: David S. Miller &lt;davem@davemloft.net&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;
</content>
</entry>
</feed>
