[moderation] [fs?] KMSAN: uninit-value in fd_install

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 05f7e89ab973 Linux 6.19
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=15cdd402580000
kernel config: https://syzkaller.appspot.com/x/.config?x=9682a42d8ec8b05c
dashboard link: https://syzkaller.appspot.com/bug?extid=fba7ca39b0dc05c3c43a
compiler: Debian clang version 21.1.8 (++20251221033036+2078da43e25a-1~exp1~20251221153213.50), Debian LLD 21.1.8
userspace arch: i386
CC: [bra...@kernel.org ja...@suse.cz linux-...@vger.kernel.org linux-...@vger.kernel.org vi...@zeniv.linux.org.uk]

Unfortunately, I don't have any reproducer for this issue yet.

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/d835883f49ba/disk-05f7e89a.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/f3a23f13e8ae/vmlinux-05f7e89a.xz
kernel image: https://storage.googleapis.com/syzbot-assets/aebdf38cc933/bzImage-05f7e89a.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+fba7ca...@syzkaller.appspotmail.com

=====================================================
BUG: KMSAN: uninit-value in fd_install+0x233/0x2f0 fs/file.c:689
fd_install+0x233/0x2f0 fs/file.c:689
do_sys_openat2+0x259/0x430 fs/open.c:1430
do_sys_open fs/open.c:1436 [inline]
__do_sys_openat fs/open.c:1452 [inline]
__se_sys_openat fs/open.c:1447 [inline]
__x64_sys_openat+0x240/0x300 fs/open.c:1447
x64_sys_call+0x3597/0x3e70 arch/x86/include/generated/asm/syscalls_64.h:258
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0xc9/0xf80 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:4960 [inline]
slab_alloc_node mm/slub.c:5263 [inline]
kmem_cache_alloc_noprof+0x967/0x1730 mm/slub.c:5270
dup_fd+0x66/0x1160 fs/file.c:390
copy_files+0x10c/0x250 kernel/fork.c:1635
copy_process+0x25ab/0x5df0 kernel/fork.c:2209
kernel_clone+0x415/0x1080 kernel/fork.c:2651
__do_sys_clone kernel/fork.c:2792 [inline]
__se_sys_clone kernel/fork.c:2776 [inline]
__x64_sys_clone+0x253/0x360 kernel/fork.c:2776
x64_sys_call+0x1666/0x3e70 arch/x86/include/generated/asm/syscalls_64.h:57
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0xc9/0xf80 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f

CPU: 1 UID: 0 PID: 5136 Comm: udevd Not tainted syzkaller #0 PREEMPT(voluntary)
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/24/2026
=====================================================


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