[syzbot] [fuse?] KMSAN: uninit-value in fuse_dentry_revalidate (2)

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 770aaedb461a Merge tag 'bootconfig-v7.0' of git://git.kern..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=158f7e5a580000
kernel config: https://syzkaller.appspot.com/x/.config?x=50148b563a4d5941
dashboard link: https://syzkaller.appspot.com/bug?extid=fdebb2dc960aa56c600a
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=138f7e5a580000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=13a5c15a580000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/24ba89b61208/disk-770aaedb.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/b38352aa3489/vmlinux-770aaedb.xz
kernel image: https://storage.googleapis.com/syzbot-assets/c388a7a46371/bzImage-770aaedb.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+fdebb2...@syzkaller.appspotmail.com

=====================================================
BUG: KMSAN: uninit-value in fuse_dentry_revalidate+0x150/0x13d0 fs/fuse/dir.c:394
fuse_dentry_revalidate+0x150/0x13d0 fs/fuse/dir.c:394
d_revalidate fs/namei.c:1030 [inline]
lookup_open fs/namei.c:4405 [inline]
open_last_lookups fs/namei.c:4583 [inline]
path_openat+0x1614/0x64c0 fs/namei.c:4827
do_file_open+0x2aa/0x680 fs/namei.c:4859
do_sys_openat2+0x163/0x380 fs/open.c:1366
do_sys_open fs/open.c:1372 [inline]
__do_sys_openat fs/open.c:1388 [inline]
__se_sys_openat fs/open.c:1383 [inline]
__x64_sys_openat+0x240/0x300 fs/open.c:1383
x64_sys_call+0x2445/0x3ea0 arch/x86/include/generated/asm/syscalls_64.h:258
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0x134/0xf80 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f

Uninit was created at:
slab_post_alloc_hook mm/slub.c:4466 [inline]
slab_alloc_node mm/slub.c:4788 [inline]
kmem_cache_alloc_lru_noprof+0x382/0x1280 mm/slub.c:4807
__d_alloc+0x55/0xa00 fs/dcache.c:1740
d_alloc_parallel+0x99/0x2740 fs/dcache.c:2604
lookup_open fs/namei.c:4398 [inline]
open_last_lookups fs/namei.c:4583 [inline]
path_openat+0x135f/0x64c0 fs/namei.c:4827
do_file_open+0x2aa/0x680 fs/namei.c:4859
do_sys_openat2+0x163/0x380 fs/open.c:1366
do_sys_open fs/open.c:1372 [inline]
__do_sys_openat fs/open.c:1388 [inline]
__se_sys_openat fs/open.c:1383 [inline]
__x64_sys_openat+0x240/0x300 fs/open.c:1383
x64_sys_call+0x2445/0x3ea0 arch/x86/include/generated/asm/syscalls_64.h:258
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0x134/0xf80 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f

CPU: 1 UID: 0 PID: 6074 Comm: syz.0.20 Not tainted syzkaller #0 PREEMPT(full)
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2026
=====================================================


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