ghsa-95rc-29j2-q3vr
Vulnerability from github
Published
2024-04-04 09:30
Modified
2024-04-04 15:30
Details

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

af_unix: Fix task hung while purging oob_skb in GC.

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: 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

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{
  "affected": [],
  "aliases": [
    "CVE-2024-26780"
  ],
  "database_specific": {
    "cwe_ids": [],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2024-04-04T09:15:07Z",
    "severity": null
  },
  "details": "In the Linux kernel, the following vulnerability has been resolved:\n\naf_unix: Fix task hung while purging oob_skb in GC.\n\nsyzbot reported a task hung; at the same time, GC was looping infinitely\nin list_for_each_entry_safe() for OOB skb.  [0]\n\nsyzbot demonstrated that the list_for_each_entry_safe() was not actually\nsafe in this case.\n\nA single skb could have references for multiple sockets.  If we free such\na skb in the list_for_each_entry_safe(), the current and next sockets could\nbe unlinked in a single iteration.\n\nunix_notinflight() uses list_del_init() to unlink the socket, so the\nprefetched next socket forms a loop itself and list_for_each_entry_safe()\nnever stops.\n\nHere, we must use while() and make sure we always fetch the first socket.\n\n[0]:\nSending NMI from CPU 0 to CPUs 1:\nNMI backtrace for cpu 1\nCPU: 1 PID: 5065 Comm: syz-executor236 Not tainted 6.8.0-rc3-syzkaller-00136-g1f719a2f3fa6 #0\nHardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/25/2024\nRIP: 0010:preempt_count arch/x86/include/asm/preempt.h:26 [inline]\nRIP: 0010:check_kcov_mode kernel/kcov.c:173 [inline]\nRIP: 0010:__sanitizer_cov_trace_pc+0xd/0x60 kernel/kcov.c:207\nCode: 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 \u003c65\u003e 8b 05 b4 7c 78 7e a9 00 01 ff 00 48 8b 34 24 74 0f f6 c4 01 74\nRSP: 0018:ffffc900033efa58 EFLAGS: 00000283\nRAX: ffff88807b077800 RBX: ffff88807b077800 RCX: 1ffffffff27b1189\nRDX: ffff88802a5a3b80 RSI: ffffffff8968488d RDI: ffff88807b077f70\nRBP: ffffc900033efbb0 R08: 0000000000000001 R09: fffffbfff27a900c\nR10: ffffffff93d48067 R11: ffffffff8ae000eb R12: ffff88807b077800\nR13: dffffc0000000000 R14: ffff88807b077e40 R15: 0000000000000001\nFS:  0000000000000000(0000) GS:ffff8880b9500000(0000) knlGS:0000000000000000\nCS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033\nCR2: 0000564f4fc1e3a8 CR3: 000000000d57a000 CR4: 00000000003506f0\nDR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000\nDR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400\nCall Trace:\n \u003cNMI\u003e\n \u003c/NMI\u003e\n \u003cTASK\u003e\n unix_gc+0x563/0x13b0 net/unix/garbage.c:319\n unix_release_sock+0xa93/0xf80 net/unix/af_unix.c:683\n unix_release+0x91/0xf0 net/unix/af_unix.c:1064\n __sock_release+0xb0/0x270 net/socket.c:659\n sock_close+0x1c/0x30 net/socket.c:1421\n __fput+0x270/0xb80 fs/file_table.c:376\n task_work_run+0x14f/0x250 kernel/task_work.c:180\n exit_task_work include/linux/task_work.h:38 [inline]\n do_exit+0xa8a/0x2ad0 kernel/exit.c:871\n do_group_exit+0xd4/0x2a0 kernel/exit.c:1020\n __do_sys_exit_group kernel/exit.c:1031 [inline]\n __se_sys_exit_group kernel/exit.c:1029 [inline]\n __x64_sys_exit_group+0x3e/0x50 kernel/exit.c:1029\n do_syscall_x64 arch/x86/entry/common.c:52 [inline]\n do_syscall_64+0xd5/0x270 arch/x86/entry/common.c:83\n entry_SYSCALL_64_after_hwframe+0x6f/0x77\nRIP: 0033:0x7f9d6cbdac09\nCode: Unable to access opcode bytes at 0x7f9d6cbdabdf.\nRSP: 002b:00007fff5952feb8 EFLAGS: 00000246 ORIG_RAX: 00000000000000e7\nRAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007f9d6cbdac09\nRDX: 000000000000003c RSI: 00000000000000e7 RDI: 0000000000000000\nRBP: 00007f9d6cc552b0 R08: ffffffffffffffb8 R09: 0000000000000006\nR10: 0000000000000006 R11: 0000000000000246 R12: 00007f9d6cc552b0\nR13: 0000000000000000 R14: 00007f9d6cc55d00 R15: 00007f9d6cbabe70\n \u003c/TASK\u003e",
  "id": "GHSA-95rc-29j2-q3vr",
  "modified": "2024-04-04T15:30:34Z",
  "published": "2024-04-04T09:30:35Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2024-26780"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/25236c91b5ab4a26a56ba2e79b8060cf4e047839"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/2a3d40b4025fcfe51b04924979f1653993b17669"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/36f7371de977f805750748e80279be7e370df85c"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/69e0f04460f4037e01e29f0d9675544f62aafca3"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/cb8890318dde26fc89c6ea67d6e9070ab50b6e91"
    }
  ],
  "schema_version": "1.4.0",
  "severity": []
}


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