| lists.openwall.net | lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC | |
|
Open Source and information security mailing list archives
| ||
|
Message-ID: <301725ba-330e-4aa4-822f-9ce2fef17b5c@nvidia.com>
Date: Thu, 5 Feb 2026 14:05:49 -0800
From: John Hubbard <jhubbard@...dia.com>
To: syzbot <syzbot+c8461425abb63bfd3445@...kaller.appspotmail.com>,
akpm@...ux-foundation.org, david@...nel.org, jgg@...pe.ca,
linux-kernel@...r.kernel.org, linux-mm@...ck.org, peterx@...hat.com,
syzkaller-bugs@...glegroups.com
Subject: Re: [syzbot] [mm?] possible deadlock in gup_fast_fallback (2)
#syz fix: procfs: avoid fetching build ID while holding VMA lock
On 2/5/26 1:44 PM, syzbot wrote:
> Hello,
>
> syzbot found the following issue on:
>
> HEAD commit: f14faaf3a1fb Merge tag 'tsm-fixes-for-6.19' of git://git.k..
> git tree: upstream
> console output: https://syzkaller.appspot.com/x/log.txt?x=10928a52580000
> kernel config: https://syzkaller.appspot.com/x/.config?x=4aae00ac5a9d2645
> dashboard link: https://syzkaller.appspot.com/bug?extid=c8461425abb63bfd3445
> compiler: Debian clang version 21.1.8 (++20251221033036+2078da43e25a-1~exp1~20251221153213.50), Debian LLD 21.1.8
> syz repro: https://syzkaller.appspot.com/x/repro.syz?x=17078a5a580000
> C reproducer: https://syzkaller.appspot.com/x/repro.c?x=14df4b22580000
>
> Downloadable assets:
> disk image (non-bootable): https://storage.googleapis.com/syzbot-assets/d900f083ada3/non_bootable_disk-f14faaf3.raw.xz
> vmlinux: https://storage.googleapis.com/syzbot-assets/2fe7f2219e97/vmlinux-f14faaf3.xz
> kernel image: https://storage.googleapis.com/syzbot-assets/b1acb6ecfb89/bzImage-f14faaf3.xz
> mounted in repro: https://storage.googleapis.com/syzbot-assets/c52bcc06e784/mount_0.gz
> fsck result: failed (log: https://syzkaller.appspot.com/x/fsck.log?x=13a5c7fa580000)
>
> IMPORTANT: if you fix the issue, please add the following tag to the commit:
> Reported-by: syzbot+c8461425abb63bfd3445@...kaller.appspotmail.com
>
> loop0: detected capacity change from 0 to 32768
> XFS (loop0): Mounting V5 Filesystem bfdc47fc-10d8-4eed-a562-11a831b3f791
> XFS (loop0): Ending clean mount
> ======================================================
> WARNING: possible circular locking dependency detected
> syzkaller #0 Not tainted
> ------------------------------------------------------
> syz.0.17/5488 is trying to acquire lock:
> ffff888044e06540 (&mm->mmap_lock){++++}-{4:4}, at: gup_fast_fallback+0x20d/0x22e0 mm/gup.c:3204
>
> but task is already holding lock:
> ffff8880467da130 (&sb->s_type->i_mutex_key#24){++++}-{4:4}, at: xfs_ilock_demote+0xbd/0x290 fs/xfs/xfs_inode.c:285
>
> which lock already depends on the new lock.
>
>
> the existing dependency chain (in reverse order) is:
>
> -> #2 (&sb->s_type->i_mutex_key#24){++++}-{4:4}:
> down_read_nested+0x49/0x2e0 kernel/locking/rwsem.c:1662
> xfs_ilock+0x109/0x360 fs/xfs/xfs_inode.c:152
> xfs_ilock_iocb fs/xfs/xfs_file.c:195 [inline]
> xfs_file_buffered_read+0x15b/0x330 fs/xfs/xfs_file.c:284
> xfs_file_read_iter+0x280/0x510 fs/xfs/xfs_file.c:312
> __kernel_read+0x504/0x9b0 fs/read_write.c:530
> freader_fetch+0x1cb/0xa00 lib/buildid.c:100
> __build_id_parse+0x168/0x870 lib/buildid.c:297
> do_procmap_query fs/proc/task_mmu.c:733 [inline]
> procfs_procmap_ioctl+0x7ae/0xd50 fs/proc/task_mmu.c:813
> vfs_ioctl fs/ioctl.c:51 [inline]
> __do_sys_ioctl fs/ioctl.c:597 [inline]
> __se_sys_ioctl+0xfc/0x170 fs/ioctl.c:583
> do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
> do_syscall_64+0xe2/0xf80 arch/x86/entry/syscall_64.c:94
> entry_SYSCALL_64_after_hwframe+0x77/0x7f
>
> -> #1 (vm_lock){++++}-{0:0}:
> __vma_enter_locked+0x243/0x710 mm/mmap_lock.c:72
> __vma_start_write+0x23/0x140 mm/mmap_lock.c:104
> vma_start_write include/linux/mmap_lock.h:213 [inline]
> mprotect_fixup+0x5e1/0xa50 mm/mprotect.c:768
> setup_arg_pages+0x565/0xae0 fs/exec.c:670
> load_elf_binary+0xc5e/0x2980 fs/binfmt_elf.c:1028
> search_binary_handler fs/exec.c:1669 [inline]
> exec_binprm fs/exec.c:1701 [inline]
> bprm_execve+0x93d/0x1410 fs/exec.c:1753
> kernel_execve+0x8ef/0x9e0 fs/exec.c:1919
> try_to_run_init_process+0x13/0x60 init/main.c:1506
> kernel_init+0xad/0x1d0 init/main.c:1634
> ret_from_fork+0x51b/0xa40 arch/x86/kernel/process.c:158
> ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:246
>
> -> #0 (&mm->mmap_lock){++++}-{4:4}:
> check_prev_add kernel/locking/lockdep.c:3165 [inline]
> check_prevs_add kernel/locking/lockdep.c:3284 [inline]
> validate_chain kernel/locking/lockdep.c:3908 [inline]
> __lock_acquire+0x15a5/0x2cf0 kernel/locking/lockdep.c:5237
> lock_acquire+0x106/0x330 kernel/locking/lockdep.c:5868
> gup_fast_fallback+0x226/0x22e0 mm/gup.c:3204
> iov_iter_extract_user_pages lib/iov_iter.c:1763 [inline]
> iov_iter_extract_pages+0x37b/0x5f0 lib/iov_iter.c:1826
> __bio_iov_iter_get_pages block/bio.c:1237 [inline]
> bio_iov_iter_get_pages+0x4a8/0x14b0 block/bio.c:1359
> iomap_dio_bio_iter+0xcb3/0x14d0 fs/iomap/direct-io.c:460
> iomap_dio_iter fs/iomap/direct-io.c:-1 [inline]
> __iomap_dio_rw+0xf57/0x1e10 fs/iomap/direct-io.c:753
> iomap_dio_rw+0x45/0xb0 fs/iomap/direct-io.c:847
> xfs_file_dio_write_aligned+0x36a/0x450 fs/xfs/xfs_file.c:707
> xfs_file_dio_write fs/xfs/xfs_file.c:910 [inline]
> xfs_file_write_iter+0x7dd/0x920 fs/xfs/xfs_file.c:1122
> new_sync_write fs/read_write.c:593 [inline]
> vfs_write+0x61d/0xb90 fs/read_write.c:686
> ksys_write+0x150/0x270 fs/read_write.c:738
> do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
> do_syscall_64+0xe2/0xf80 arch/x86/entry/syscall_64.c:94
> entry_SYSCALL_64_after_hwframe+0x77/0x7f
>
> other info that might help us debug this:
>
> Chain exists of:
> &mm->mmap_lock --> vm_lock --> &sb->s_type->i_mutex_key#24
>
> Possible unsafe locking scenario:
>
> CPU0 CPU1
> ---- ----
> rlock(&sb->s_type->i_mutex_key#24);
> lock(vm_lock);
> lock(&sb->s_type->i_mutex_key#24);
> rlock(&mm->mmap_lock);
>
> *** DEADLOCK ***
>
> 2 locks held by syz.0.17/5488:
> #0: ffff888031ac6420 (sb_writers#12){.+.+}-{0:0}, at: file_start_write include/linux/fs.h:2683 [inline]
> #0: ffff888031ac6420 (sb_writers#12){.+.+}-{0:0}, at: vfs_write+0x227/0xb90 fs/read_write.c:682
> #1: ffff8880467da130 (&sb->s_type->i_mutex_key#24){++++}-{4:4}, at: xfs_ilock_demote+0xbd/0x290 fs/xfs/xfs_inode.c:285
>
> stack backtrace:
> CPU: 0 UID: 0 PID: 5488 Comm: syz.0.17 Not tainted syzkaller #0 PREEMPT(full)
> Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2 04/01/2014
> Call Trace:
> <TASK>
> dump_stack_lvl+0xe8/0x150 lib/dump_stack.c:120
> print_circular_bug+0x2e1/0x300 kernel/locking/lockdep.c:2043
> check_noncircular+0x12e/0x150 kernel/locking/lockdep.c:2175
> check_prev_add kernel/locking/lockdep.c:3165 [inline]
> check_prevs_add kernel/locking/lockdep.c:3284 [inline]
> validate_chain kernel/locking/lockdep.c:3908 [inline]
> __lock_acquire+0x15a5/0x2cf0 kernel/locking/lockdep.c:5237
> lock_acquire+0x106/0x330 kernel/locking/lockdep.c:5868
> gup_fast_fallback+0x226/0x22e0 mm/gup.c:3204
> iov_iter_extract_user_pages lib/iov_iter.c:1763 [inline]
> iov_iter_extract_pages+0x37b/0x5f0 lib/iov_iter.c:1826
> __bio_iov_iter_get_pages block/bio.c:1237 [inline]
> bio_iov_iter_get_pages+0x4a8/0x14b0 block/bio.c:1359
> iomap_dio_bio_iter+0xcb3/0x14d0 fs/iomap/direct-io.c:460
> iomap_dio_iter fs/iomap/direct-io.c:-1 [inline]
> __iomap_dio_rw+0xf57/0x1e10 fs/iomap/direct-io.c:753
> iomap_dio_rw+0x45/0xb0 fs/iomap/direct-io.c:847
> xfs_file_dio_write_aligned+0x36a/0x450 fs/xfs/xfs_file.c:707
> xfs_file_dio_write fs/xfs/xfs_file.c:910 [inline]
> xfs_file_write_iter+0x7dd/0x920 fs/xfs/xfs_file.c:1122
> new_sync_write fs/read_write.c:593 [inline]
> vfs_write+0x61d/0xb90 fs/read_write.c:686
> ksys_write+0x150/0x270 fs/read_write.c:738
> do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
> do_syscall_64+0xe2/0xf80 arch/x86/entry/syscall_64.c:94
> entry_SYSCALL_64_after_hwframe+0x77/0x7f
> RIP: 0033:0x7f85b679aeb9
> Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 e8 ff ff ff f7 d8 64 89 01 48
> RSP: 002b:00007ffd910b1588 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
> RAX: ffffffffffffffda RBX: 00007f85b6a15fa0 RCX: 00007f85b679aeb9
> RDX: 000000000000f000 RSI: 0000200000000200 RDI: 0000000000000007
> RBP: 00007f85b6808c1f R08: 0000000000000000 R09: 0000000000000000
> R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
> R13: 00007f85b6a15fac R14: 00007f85b6a15fa0 R15: 00007f85b6a15fa0
> </TASK>
>
>
> ---
> This report is generated by a bot. It may contain errors.
> See https://goo.gl/tpsmEJ for more information about syzbot.
> syzbot engineers can be reached at syzkaller@...glegroups.com.
>
> syzbot will keep track of this issue. See:
> https://goo.gl/tpsmEJ#status for how to communicate with syzbot.
>
> If the report is already addressed, let syzbot know by replying with:
> #syz fix: exact-commit-title
>
> If you want syzbot to run the reproducer, reply with:
> #syz test: git://repo/address.git branch-or-commit-hash
> If you attach or paste a git patch, syzbot will apply it before testing.
>
> If you want to overwrite report's subsystems, reply with:
> #syz set subsystems: new-subsystem
> (See the list of subsystem names on the web dashboard)
>
> If the report is a duplicate of another one, reply with:
> #syz dup: exact-subject-of-another-report
>
> If you want to undo deduplication, reply with:
> #syz undup
thanks,
--
John Hubbard
Powered by blists - more mailing lists