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Kuniyuki Iwashima 2a3d40b402 af_unix: Fix task hung while purging oob_skb in GC.
[ Upstream commit 25236c91b5 ]

syzbot reported a task hung; at the same time, GC was looping infinitely
in list_for_each_entry_safe() for OOB skb.  [0]

syzbot demonstrated that the list_for_each_entry_safe() was not actually
safe in this case.

A single skb could have references for multiple sockets.  If we free such
a skb in the list_for_each_entry_safe(), the current and next sockets could
be unlinked in a single iteration.

unix_notinflight() uses list_del_init() to unlink the socket, so the
prefetched next socket forms a loop itself and list_for_each_entry_safe()
never stops.

Here, we must use while() and make sure we always fetch the first socket.

[0]:
Sending NMI from CPU 0 to CPUs 1:
NMI backtrace for cpu 1
CPU: 1 PID: 5065 Comm: syz-executor236 Not tainted 6.8.0-rc3-syzkaller-00136-g1f719a2f3fa6 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/25/2024
RIP: 0010:preempt_count arch/x86/include/asm/preempt.h:26 [inline]
RIP: 0010:check_kcov_mode kernel/kcov.c:173 [inline]
RIP: 0010:__sanitizer_cov_trace_pc+0xd/0x60 kernel/kcov.c:207
Code: cc cc cc cc 66 0f 1f 84 00 00 00 00 00 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 f3 0f 1e fa 65 48 8b 14 25 40 c2 03 00 <65> 8b 05 b4 7c 78 7e a9 00 01 ff 00 48 8b 34 24 74 0f f6 c4 01 74
RSP: 0018:ffffc900033efa58 EFLAGS: 00000283
RAX: ffff88807b077800 RBX: ffff88807b077800 RCX: 1ffffffff27b1189
RDX: ffff88802a5a3b80 RSI: ffffffff8968488d RDI: ffff88807b077f70
RBP: ffffc900033efbb0 R08: 0000000000000001 R09: fffffbfff27a900c
R10: ffffffff93d48067 R11: ffffffff8ae000eb R12: ffff88807b077800
R13: dffffc0000000000 R14: ffff88807b077e40 R15: 0000000000000001
FS:  0000000000000000(0000) GS:ffff8880b9500000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000564f4fc1e3a8 CR3: 000000000d57a000 CR4: 00000000003506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <NMI>
 </NMI>
 <TASK>
 unix_gc+0x563/0x13b0 net/unix/garbage.c:319
 unix_release_sock+0xa93/0xf80 net/unix/af_unix.c:683
 unix_release+0x91/0xf0 net/unix/af_unix.c:1064
 __sock_release+0xb0/0x270 net/socket.c:659
 sock_close+0x1c/0x30 net/socket.c:1421
 __fput+0x270/0xb80 fs/file_table.c:376
 task_work_run+0x14f/0x250 kernel/task_work.c:180
 exit_task_work include/linux/task_work.h:38 [inline]
 do_exit+0xa8a/0x2ad0 kernel/exit.c:871
 do_group_exit+0xd4/0x2a0 kernel/exit.c:1020
 __do_sys_exit_group kernel/exit.c:1031 [inline]
 __se_sys_exit_group kernel/exit.c:1029 [inline]
 __x64_sys_exit_group+0x3e/0x50 kernel/exit.c:1029
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xd5/0x270 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x6f/0x77
RIP: 0033:0x7f9d6cbdac09
Code: Unable to access opcode bytes at 0x7f9d6cbdabdf.
RSP: 002b:00007fff5952feb8 EFLAGS: 00000246 ORIG_RAX: 00000000000000e7
RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007f9d6cbdac09
RDX: 000000000000003c RSI: 00000000000000e7 RDI: 0000000000000000
RBP: 00007f9d6cc552b0 R08: ffffffffffffffb8 R09: 0000000000000006
R10: 0000000000000006 R11: 0000000000000246 R12: 00007f9d6cc552b0
R13: 0000000000000000 R14: 00007f9d6cc55d00 R15: 00007f9d6cbabe70
 </TASK>

Reported-by: syzbot+4fa4a2d1f5a5ee06f006@syzkaller.appspotmail.com
Closes: https://syzkaller.appspot.com/bug?extid=4fa4a2d1f5a5ee06f006
Fixes: 1279f9d9de ("af_unix: Call kfree_skb() for dead unix_(sk)->oob_skb in GC.")
Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Link: https://lore.kernel.org/r/20240209220453.96053-1-kuniyu@amazon.com
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
History 2024-03-06 14:45:04 +00:00
arch s390: use the correct count for __iowrite64_copy() 2024-03-01 13:26:37 +01:00
block block: Fix WARNING in _copy_from_iter 2024-03-01 13:26:25 +01:00
certs certs: Fix build error when PKCS#11 URI contains semicolon 2023-02-09 11:28:11 +01:00
crypto crypto: api - Disallow identical driver names 2024-01-31 16:16:58 -08:00
Documentation arm64: Subscribe Microsoft Azure Cobalt 100 to ARM Neoverse N2 errata 2024-02-23 09:12:52 +01:00
drivers scsi: sd: usb_storage: uas: Access media prior to querying device properties 2024-03-06 14:45:04 +00:00
fs fs/ntfs3: Enhance the attribute size check 2024-03-01 13:26:39 +01:00
include scsi: sd: usb_storage: uas: Access media prior to querying device properties 2024-03-06 14:45:04 +00:00
init update workarounds for gcc "asm goto" issue 2024-02-23 09:12:28 +01:00
io_uring io_uring/net: fix multishot accept overflow handling 2024-02-23 09:12:43 +01:00
ipc ipc: fix memory leak in init_mqueue_fs() 2022-12-31 13:32:01 +01:00
kernel bpf: Fix racing between bpf_timer_cancel_and_free and bpf_timer_cancel 2024-03-01 13:26:36 +01:00
lib crypto: lib/mpi - Fix unexpected pointer access in mpi_ec_init 2024-02-23 09:12:49 +01:00
LICENSES LICENSES/LGPL-2.1: Add LGPL-2.1-or-later as valid identifiers 2021-12-16 14:33:10 +01:00
mm mm: zswap: fix missing folio cleanup in writeback race path 2024-03-01 13:26:39 +01:00
net af_unix: Fix task hung while purging oob_skb in GC. 2024-03-06 14:45:04 +00:00
rust rust: allocator: Prevent mis-aligned allocation 2023-08-11 12:08:18 +02:00
samples work around gcc bugs with 'asm goto' with outputs 2024-02-23 09:12:28 +01:00
scripts bpf, scripts: Correct GPL license name 2024-03-01 13:26:35 +01:00
security apparmor: Free up __cleanup() name 2024-02-23 09:12:51 +01:00
sound ALSA: usb-audio: Ignore clock selector errors for single connection 2024-03-01 13:26:27 +01:00
tools net/sched: Retire dsmark qdisc 2024-03-01 13:26:24 +01:00
usr usr/gen_init_cpio.c: remove unnecessary -1 values from int file 2022-10-03 14:21:44 -07:00
virt kvm/vfio: ensure kvg instance stays around in kvm_vfio_group_add() 2023-09-13 09:42:46 +02:00
.clang-format inet: ping: use hlist_nulls rcu iterator during lookup 2022-12-01 12:42:46 +01:00
.cocciconfig scripts: add Linux .cocciconfig for coccinelle 2016-07-22 12:13:39 +02:00
.get_maintainer.ignore get_maintainer: add Alan to .get_maintainer.ignore 2022-08-20 15:17:44 -07:00
.gitattributes .gitattributes: use 'dts' diff driver for dts files 2019-12-04 19:44:11 -08:00
.gitignore Kbuild: add Rust support 2022-09-28 09:02:20 +02:00
.mailmap 9 hotfixes. 6 for MM, 3 for other areas. Four of these patches address 2022-12-10 17:10:52 -08:00
.rustfmt.toml rust: add .rustfmt.toml 2022-09-28 09:02:20 +02:00
COPYING COPYING: state that all contributions really are covered by this file 2020-02-10 13:32:20 -08:00
CREDITS MAINTAINERS: Remove Michal Marek from Kbuild maintainers 2022-11-16 14:53:00 +09:00
Kbuild Kbuild updates for v6.1 2022-10-10 12:00:45 -07:00
Kconfig kbuild: ensure full rebuild when the compiler is updated 2020-05-12 13:28:33 +09:00
MAINTAINERS genirq/affinity: Move group_cpus_evenly() into lib/ 2024-01-10 17:10:33 +01:00
Makefile Linux 6.1.80 2024-03-01 13:26:39 +01:00
README Drop all 00-INDEX files from Documentation/ 2018-09-09 15:08:58 -06:00

Linux kernel
============

There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.

In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``.  The formatted documentation can also be read online at:

    https://www.kernel.org/doc/html/latest/

There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.

Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.