syzbot


KMSAN: uninit-value in fuse_dentry_revalidate

Status: upstream: reported on 2025/09/24 10:21
Subsystems: fuse
[Documentation on labels]
Reported-by: syzbot+743e3f809752d6f7934f@syzkaller.appspotmail.com
First crash: 5d13h, last: 1d16h
Discussions (1)
Title Replies (including bot) Last reply
[syzbot] [fuse?] KMSAN: uninit-value in fuse_dentry_revalidate 0 (1) 2025/09/24 10:21

Sample crash report:
=====================================================
BUG: KMSAN: uninit-value in fuse_dentry_revalidate+0x150/0x13a0 fs/fuse/dir.c:208
 fuse_dentry_revalidate+0x150/0x13a0 fs/fuse/dir.c:208
 d_revalidate fs/namei.c:929 [inline]
 lookup_open fs/namei.c:3637 [inline]
 open_last_lookups fs/namei.c:3807 [inline]
 path_openat+0x13a9/0x6760 fs/namei.c:4043
 do_filp_open+0x280/0x660 fs/namei.c:4073
 do_sys_openat2+0x1bb/0x2f0 fs/open.c:1435
 do_sys_open fs/open.c:1450 [inline]
 __do_compat_sys_openat fs/open.c:1512 [inline]
 __se_compat_sys_openat fs/open.c:1510 [inline]
 __ia32_compat_sys_openat+0x238/0x300 fs/open.c:1510
 ia32_sys_call+0x3210/0x4310 arch/x86/include/generated/asm/syscalls_32.h:296
 do_syscall_32_irqs_on arch/x86/entry/syscall_32.c:83 [inline]
 __do_fast_syscall_32+0xb0/0x150 arch/x86/entry/syscall_32.c:306
 do_fast_syscall_32+0x38/0x80 arch/x86/entry/syscall_32.c:331
 do_SYSENTER_32+0x1f/0x30 arch/x86/entry/syscall_32.c:369
 entry_SYSENTER_compat_after_hwframe+0x84/0x8e

Uninit was created at:
 slab_post_alloc_hook mm/slub.c:4197 [inline]
 slab_alloc_node mm/slub.c:4240 [inline]
 kmem_cache_alloc_lru_noprof+0x822/0xed0 mm/slub.c:4259
 __d_alloc+0x66/0xa60 fs/dcache.c:1690
 d_alloc_parallel+0x98/0x2680 fs/dcache.c:2549
 __lookup_slow+0x138/0x760 fs/namei.c:1793
 lookup_slow+0x6a/0xd0 fs/namei.c:1825
 walk_component+0x444/0x650 fs/namei.c:2129
 lookup_last fs/namei.c:2630 [inline]
 path_lookupat+0x251/0x6b0 fs/namei.c:2654
 filename_lookup+0x2bd/0x800 fs/namei.c:2683
 do_linkat+0x14e/0x1040 fs/namei.c:4904
 __do_sys_link fs/namei.c:4958 [inline]
 __se_sys_link fs/namei.c:4956 [inline]
 __ia32_sys_link+0xd7/0x140 fs/namei.c:4956
 ia32_sys_call+0x3684/0x4310 arch/x86/include/generated/asm/syscalls_32.h:10
 do_syscall_32_irqs_on arch/x86/entry/syscall_32.c:83 [inline]
 __do_fast_syscall_32+0xb0/0x150 arch/x86/entry/syscall_32.c:306
 do_fast_syscall_32+0x38/0x80 arch/x86/entry/syscall_32.c:331
 do_SYSENTER_32+0x1f/0x30 arch/x86/entry/syscall_32.c:369
 entry_SYSENTER_compat_after_hwframe+0x84/0x8e

CPU: 0 UID: 0 PID: 8754 Comm: syz.4.604 Not tainted syzkaller #0 PREEMPT(none) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/18/2025
=====================================================

Crashes (2):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2025/09/24 07:15 upstream cec1e6e5d1ab 0abd0691 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kmsan-gce-386-root KMSAN: uninit-value in fuse_dentry_revalidate
2025/09/20 10:19 upstream cd89d487374c 67c37560 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kmsan-gce-386-root KMSAN: uninit-value in fuse_dentry_revalidate
* Struck through repros no longer work on HEAD.