On Mon, Sep 2, 2024 at 4:37 AM Thomas Gleixner <[email protected]> wrote: > > On Mon, Aug 26 2024 at 01:29, syzbot wrote: > > Cc:+ seccomp and audit folks > > > syzbot found the following issue on: > > > > HEAD commit: 6a7917c89f21 Add linux-next specific files for 20240822 > > git tree: linux-next > > console output: https://syzkaller.appspot.com/x/log.txt?x=15c8680b980000 > > kernel config: https://syzkaller.appspot.com/x/.config?x=897bd7c53a10fcfc > > dashboard link: https://syzkaller.appspot.com/bug?extid=4576eaa688ef747b8d6c > > compiler: Debian clang version 15.0.6, GNU ld (GNU Binutils for > > Debian) 2.40 > > > > Unfortunately, I don't have any reproducer for this issue yet. > > > > Downloadable assets: > > disk image: > > https://storage.googleapis.com/syzbot-assets/47820545bc51/disk-6a7917c8.raw.xz > > vmlinux: > > https://storage.googleapis.com/syzbot-assets/e300f3a38860/vmlinux-6a7917c8.xz > > kernel image: > > https://storage.googleapis.com/syzbot-assets/9146afef58aa/bzImage-6a7917c8.xz > > > > IMPORTANT: if you fix the issue, please add the following tag to the commit: > > Reported-by: [email protected] > > > > WARNING: CPU: 1 PID: 8527 at kernel/sched/core.c:8556 > > __might_sleep+0xb9/0xe0 kernel/sched/core.c:8552 > > Modules linked in: > > CPU: 1 UID: 0 PID: 8527 Comm: syz.4.642 Not tainted > > 6.11.0-rc4-next-20240822-syzkaller #0 > > Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS > > Google 08/06/2024 > > RIP: 0010:__might_sleep+0xb9/0xe0 kernel/sched/core.c:8552 > > Code: a1 0e 01 90 42 80 3c 23 00 74 08 48 89 ef e8 ce e6 97 00 48 8b 4d 00 > > 48 c7 c7 c0 60 0a 8c 44 89 ee 48 89 ca e8 f8 02 f1 ff 90 <0f> 0b 90 90 eb > > b5 89 d9 80 e1 07 80 c1 03 38 c1 0f 8c 70 ff ff ff > > RSP: 0018:ffffc90009ab7a20 EFLAGS: 00010246 > > RAX: a60a1ffb5c104900 RBX: 1ffff11004257a6c RCX: 0000000000040000 > > RDX: ffffc90003e59000 RSI: 000000000001b727 RDI: 000000000001b728 > > RBP: ffff8880212bd360 R08: ffffffff8155a632 R09: fffffbfff1cfa364 > > R10: dffffc0000000000 R11: fffffbfff1cfa364 R12: dffffc0000000000 > > R13: 0000000000000002 R14: 0000000000000151 R15: ffffffff8e0a492c > > FS: 00007f4cf5b6a6c0(0000) GS:ffff8880b9100000(0000) knlGS:0000000000000000 > > CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 > > CR2: 00007f7e0f003000 CR3: 000000001feec000 CR4: 00000000003506f0 > > DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 > > DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 > > Call Trace: > > <TASK> > > might_alloc include/linux/sched/mm.h:337 [inline] > > slab_pre_alloc_hook mm/slub.c:3987 [inline] > > slab_alloc_node mm/slub.c:4065 [inline] > > kmem_cache_alloc_noprof+0x5d/0x2a0 mm/slub.c:4092 > > audit_buffer_alloc kernel/audit.c:1790 [inline] > > audit_log_start+0x15e/0xa30 kernel/audit.c:1912 > > audit_seccomp+0x63/0x1f0 kernel/auditsc.c:3007
The audit_seccomp() function allocates an audit buffer using GFP_KERNEL, which should be the source of the might_sleep. We can fix that easily enough by moving to GFP_ATOMIC (either for just this code path or all callers, need to check that), but I just want to confirm that we can't sleep here? I haven't dug into the syscall code in a while, so I don't recall all the details, but it seems odd to me that we can't safely sleep here ... > > seccomp_log kernel/seccomp.c:1016 [inline] > > __seccomp_filter+0xb38/0x1fe0 kernel/seccomp.c:1305 > > syscall_trace_enter+0xa8/0x150 kernel/entry/common.c:52 > > syscall_enter_from_user_mode_work include/linux/entry-common.h:168 [inline] > > syscall_enter_from_user_mode include/linux/entry-common.h:198 [inline] > > do_syscall_64+0xcc/0x230 arch/x86/entry/common.c:79 > > entry_SYSCALL_64_after_hwframe+0x77/0x7f > > RIP: 0033:0x7f4cf4d157e9 > > Code: 64 c7 00 16 00 00 00 b8 ff ff ff ff c3 0f 1f 40 00 90 66 66 2e 0f 1f > > 84 00 00 00 00 00 0f 1f 40 00 48 c7 c0 0f 00 00 00 0f 05 <0f> 1f 80 00 00 > > 00 00 48 81 ec 48 01 00 00 49 89 d0 64 48 8b 04 25 > > RSP: 002b:00007f4cf5b69b40 EFLAGS: 00000206 ORIG_RAX: 000000000000000f > > RAX: ffffffffffffffda RBX: 00007f4cf4f15f88 RCX: 00007f4cf4d157e9 > > RDX: 00007f4cf5b69b40 RSI: 00007f4cf5b69c70 RDI: 0000000000000021 > > RBP: 00007f4cf4f15f80 R08: 0000000000000000 R09: 0000000000000000 > > R10: 0000000000000000 R11: 0000000000000206 R12: 00007f4cf4f15f8c > > R13: 0000000000000000 R14: 00007fffe8828e10 R15: 00007fffe8828ef8 > > </TASK> -- paul-moore.com
