CVE-2022-50259

In the Linux kernel, the following vulnerability has been resolved:

bpf, sockmap: fix race in sock_map_free()

sock_map_free() calls release_sock(sk) without owning a reference

on the socket. This can cause use-after-free as syzbot found [1]

Jakub Sitnicki already took care of a similar issue

in sock_hash_free() in commit 75e68e5bf2c7 ("bpf, sockhash:

Synchronize delete from bucket list on map free")

[1]

refcount_t: decrement hit 0; leaking memory.

WARNING: CPU: 0 PID: 3785 at lib/refcount.c:31 refcount_warn_saturate+0x17c/0x1a0 lib/refcount.c:31

Modules linked in:

CPU: 0 PID: 3785 Comm: kworker/u4:6 Not tainted 6.1.0-rc7-syzkaller-00103-gef4d3ea40565 #0

Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/26/2022

Workqueue: events_unbound bpf_map_free_deferred

RIP: 0010:refcount_warn_saturate+0x17c/0x1a0 lib/refcount.c:31

Code: 68 8b 31 c0 e8 75 71 15 fd 0f 0b e9 64 ff ff ff e8 d9 6e 4e fd c6 05 62 9c 3d 0a 01 48 c7 c7 80 bb 68 8b 31 c0 e8 54 71 15 fd <0f> 0b e9 43 ff ff ff 89 d9 80 e1 07 80 c1 03 38 c1 0f 8c a2 fe ff

RSP: 0018:ffffc9000456fb60 EFLAGS: 00010246

RAX: eae59bab72dcd700 RBX: 0000000000000004 RCX: ffff8880207057c0

RDX: 0000000000000000 RSI: 0000000000000201 RDI: 0000000000000000

RBP: 0000000000000004 R08: ffffffff816fdabd R09: fffff520008adee5

R10: fffff520008adee5 R11: 1ffff920008adee4 R12: 0000000000000004

R13: dffffc0000000000 R14: ffff88807b1c6c00 R15: 1ffff1100f638dcf

FS: 0000000000000000(0000) GS:ffff8880b9800000(0000) knlGS:0000000000000000

CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033

CR2: 0000001b30c30000 CR3: 000000000d08e000 CR4: 00000000003506f0

DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000

DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400

Call Trace:

<TASK>

__refcount_dec include/linux/refcount.h:344 [inline]

refcount_dec include/linux/refcount.h:359 [inline]

__sock_put include/net/sock.h:779 [inline]

tcp_release_cb+0x2d0/0x360 net/ipv4/tcp_output.c:1092

release_sock+0xaf/0x1c0 net/core/sock.c:3468

sock_map_free+0x219/0x2c0 net/core/sock_map.c:356

process_one_work+0x81c/0xd10 kernel/workqueue.c:2289

worker_thread+0xb14/0x1330 kernel/workqueue.c:2436

kthread+0x266/0x300 kernel/kthread.c:376

ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:306

</TASK>