| From bippy-5f407fcff5a0 Mon Sep 17 00:00:00 2001 |
| From: Greg Kroah-Hartman <gregkh@linuxfoundation.org> |
| To: <linux-cve-announce@vger.kernel.org> |
| Reply-to: <cve@kernel.org>, <linux-kernel@vger.kernel.org> |
| Subject: CVE-2024-26750: af_unix: Drop oob_skb ref before purging queue in GC. |
| |
| Description |
| =========== |
| |
| In the Linux kernel, the following vulnerability has been resolved: |
| |
| af_unix: Drop oob_skb ref before purging queue in GC. |
| |
| syzbot reported another task hung in __unix_gc(). [0] |
| |
| The current while loop assumes that all of the left candidates |
| have oob_skb and calling kfree_skb(oob_skb) releases the remaining |
| candidates. |
| |
| However, I missed a case that oob_skb has self-referencing fd and |
| another fd and the latter sk is placed before the former in the |
| candidate list. Then, the while loop never proceeds, resulting |
| the task hung. |
| |
| __unix_gc() has the same loop just before purging the collected skb, |
| so we can call kfree_skb(oob_skb) there and let __skb_queue_purge() |
| release all inflight sockets. |
| |
| [0]: |
| Sending NMI from CPU 0 to CPUs 1: |
| NMI backtrace for cpu 1 |
| CPU: 1 PID: 2784 Comm: kworker/u4:8 Not tainted 6.8.0-rc4-syzkaller-01028-g71b605d32017 #0 |
| Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/25/2024 |
| Workqueue: events_unbound __unix_gc |
| RIP: 0010:__sanitizer_cov_trace_pc+0x0/0x70 kernel/kcov.c:200 |
| Code: 89 fb e8 23 00 00 00 48 8b 3d 84 f5 1a 0c 48 89 de 5b e9 43 26 57 00 0f 1f 00 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 <f3> 0f 1e fa 48 8b 04 24 65 48 8b 0d 90 52 70 7e 65 8b 15 91 52 70 |
| RSP: 0018:ffffc9000a17fa78 EFLAGS: 00000287 |
| RAX: ffffffff8a0a6108 RBX: ffff88802b6c2640 RCX: ffff88802c0b3b80 |
| RDX: 0000000000000000 RSI: 0000000000000002 RDI: 0000000000000000 |
| RBP: ffffc9000a17fbf0 R08: ffffffff89383f1d R09: 1ffff1100ee5ff84 |
| R10: dffffc0000000000 R11: ffffed100ee5ff85 R12: 1ffff110056d84ee |
| R13: ffffc9000a17fae0 R14: 0000000000000000 R15: ffffffff8f47b840 |
| FS: 0000000000000000(0000) GS:ffff8880b9500000(0000) knlGS:0000000000000000 |
| CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 |
| CR2: 00007ffef5687ff8 CR3: 0000000029b34000 CR4: 00000000003506f0 |
| DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 |
| DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 |
| Call Trace: |
| <NMI> |
| </NMI> |
| <TASK> |
| __unix_gc+0xe69/0xf40 net/unix/garbage.c:343 |
| process_one_work kernel/workqueue.c:2633 [inline] |
| process_scheduled_works+0x913/0x1420 kernel/workqueue.c:2706 |
| worker_thread+0xa5f/0x1000 kernel/workqueue.c:2787 |
| kthread+0x2ef/0x390 kernel/kthread.c:388 |
| ret_from_fork+0x4b/0x80 arch/x86/kernel/process.c:147 |
| ret_from_fork_asm+0x1b/0x30 arch/x86/entry/entry_64.S:242 |
| </TASK> |
| |
| The Linux kernel CVE team has assigned CVE-2024-26750 to this issue. |
| |
| |
| Affected and fixed versions |
| =========================== |
| |
| Issue introduced in 5.15.149 with commit 36f7371de977f805750748e80279be7e370df85c and fixed in 5.15.151 with commit 6c480d0f131862645d172ca9e25dc152b1a5c3a6 |
| |
| Please see https://www.kernel.org for a full list of currently supported |
| kernel versions by the kernel community. |
| |
| Unaffected versions might change over time as fixes are backported to |
| older supported kernel versions. The official CVE entry at |
| https://cve.org/CVERecord/?id=CVE-2024-26750 |
| will be updated if fixes are backported, please check that for the most |
| up to date information about this issue. |
| |
| |
| Affected files |
| ============== |
| |
| The file(s) affected by this issue are: |
| net/unix/garbage.c |
| |
| |
| Mitigation |
| ========== |
| |
| The Linux kernel CVE team recommends that you update to the latest |
| stable kernel version for this, and many other bugfixes. Individual |
| changes are never tested alone, but rather are part of a larger kernel |
| release. Cherry-picking individual commits is not recommended or |
| supported by the Linux kernel community at all. If however, updating to |
| the latest release is impossible, the individual changes to resolve this |
| issue can be found at these commits: |
| https://git.kernel.org/stable/c/6c480d0f131862645d172ca9e25dc152b1a5c3a6 |
| https://git.kernel.org/stable/c/c4c795b21dd23d9514ae1c6646c3fb2c78b5be60 |
| https://git.kernel.org/stable/c/e9eac260369d0cf57ea53df95427125725507a0d |
| https://git.kernel.org/stable/c/43ba9e331559a30000c862eea313248707afa787 |
| https://git.kernel.org/stable/c/aa82ac51d63328714645c827775d64dbfd9941f3 |
