* [syzbot] [fuse?] KMSAN: uninit-value in fuse_fileattr_get
@ 2026-02-06 3:37 syzbot
2026-02-06 3:46 ` Qing Wang
` (2 more replies)
0 siblings, 3 replies; 6+ messages in thread
From: syzbot @ 2026-02-06 3:37 UTC (permalink / raw)
To: linux-fsdevel, linux-kernel, miklos, syzkaller-bugs
Hello,
syzbot found the following issue on:
HEAD commit: 18f7fcd5e69a Linux 6.19-rc8
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=16bafc5a580000
kernel config: https://syzkaller.appspot.com/x/.config?x=9682a42d8ec8b05c
dashboard link: https://syzkaller.appspot.com/bug?extid=7c31755f2cea07838b0c
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=1329b322580000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=178a425a580000
Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/c8e19a1c3a97/disk-18f7fcd5.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/ffdc9733836e/vmlinux-18f7fcd5.xz
kernel image: https://storage.googleapis.com/syzbot-assets/8cdf30f0d2d2/bzImage-18f7fcd5.xz
IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+7c31755f2cea07838b0c@syzkaller.appspotmail.com
=====================================================
BUG: KMSAN: uninit-value in fuse_fileattr_get+0xeb4/0x1450 fs/fuse/ioctl.c:517
fuse_fileattr_get+0xeb4/0x1450 fs/fuse/ioctl.c:517
vfs_fileattr_get fs/file_attr.c:94 [inline]
__do_sys_file_getattr fs/file_attr.c:416 [inline]
__se_sys_file_getattr+0x6cb/0xbd0 fs/file_attr.c:372
__x64_sys_file_getattr+0xe4/0x150 fs/file_attr.c:372
x64_sys_call+0x17cd/0x3e70 arch/x86/include/generated/asm/syscalls_64.h:469
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
Local variable fa.i created at:
__do_sys_file_getattr fs/file_attr.c:380 [inline]
__se_sys_file_getattr+0x8c/0xbd0 fs/file_attr.c:372
__x64_sys_file_getattr+0xe4/0x150 fs/file_attr.c:372
CPU: 1 UID: 0 PID: 6065 Comm: syz.0.18 Not tainted syzkaller #0 PREEMPT(voluntary)
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/24/2026
=====================================================
---
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If the report is already addressed, let syzbot know by replying with:
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^ permalink raw reply [flat|nested] 6+ messages in thread* Re: [syzbot] [fuse?] KMSAN: uninit-value in fuse_fileattr_get
2026-02-06 3:37 [syzbot] [fuse?] KMSAN: uninit-value in fuse_fileattr_get syzbot
@ 2026-02-06 3:46 ` Qing Wang
2026-02-06 4:16 ` syzbot
2026-02-06 6:00 ` Qing Wang
2026-02-06 6:20 ` [PATCH] fs: init flags_valid before calling vfs_fileattr_get Edward Adam Davis
2 siblings, 1 reply; 6+ messages in thread
From: Qing Wang @ 2026-02-06 3:46 UTC (permalink / raw)
To: syzbot+7c31755f2cea07838b0c
Cc: linux-fsdevel, linux-kernel, miklos, syzkaller-bugs
#syz test
diff --git a/fs/file_attr.c b/fs/file_attr.c
index 13cdb31a3e94..4f514e487e35 100644
--- a/fs/file_attr.c
+++ b/fs/file_attr.c
@@ -413,6 +413,7 @@ SYSCALL_DEFINE5(file_getattr, int, dfd, const char __user *, filename,
return error;
}
+ memset(&fa, 0, sizeof(struct file_kattr));
error = vfs_fileattr_get(filepath.dentry, &fa);
if (error == -ENOIOCTLCMD || error == -ENOTTY)
error = -EOPNOTSUPP;
^ permalink raw reply related [flat|nested] 6+ messages in thread
* Re: [syzbot] [fuse?] KMSAN: uninit-value in fuse_fileattr_get
2026-02-06 3:37 [syzbot] [fuse?] KMSAN: uninit-value in fuse_fileattr_get syzbot
2026-02-06 3:46 ` Qing Wang
@ 2026-02-06 6:00 ` Qing Wang
2026-02-06 6:53 ` syzbot
2026-02-06 6:20 ` [PATCH] fs: init flags_valid before calling vfs_fileattr_get Edward Adam Davis
2 siblings, 1 reply; 6+ messages in thread
From: Qing Wang @ 2026-02-06 6:00 UTC (permalink / raw)
To: syzbot+7c31755f2cea07838b0c
Cc: linux-fsdevel, linux-kernel, miklos, syzkaller-bugs
#syz test
diff --git a/fs/file_attr.c b/fs/file_attr.c
index 13cdb31a3e94..8b5565cbccb0 100644
--- a/fs/file_attr.c
+++ b/fs/file_attr.c
@@ -377,7 +377,7 @@ SYSCALL_DEFINE5(file_getattr, int, dfd, const char __user *, filename,
struct filename *name __free(putname) = NULL;
unsigned int lookup_flags = 0;
struct file_attr fattr;
- struct file_kattr fa;
+ struct file_kattr fa = {};
int error;
BUILD_BUG_ON(sizeof(struct file_attr) < FILE_ATTR_SIZE_VER0);
^ permalink raw reply related [flat|nested] 6+ messages in thread* [PATCH] fs: init flags_valid before calling vfs_fileattr_get
2026-02-06 3:37 [syzbot] [fuse?] KMSAN: uninit-value in fuse_fileattr_get syzbot
2026-02-06 3:46 ` Qing Wang
2026-02-06 6:00 ` Qing Wang
@ 2026-02-06 6:20 ` Edward Adam Davis
2 siblings, 0 replies; 6+ messages in thread
From: Edward Adam Davis @ 2026-02-06 6:20 UTC (permalink / raw)
To: syzbot+7c31755f2cea07838b0c
Cc: linux-fsdevel, linux-kernel, miklos, brauner, aalbersh,
syzkaller-bugs
syzbot reported a uninit-value bug in [1].
Similar to the "*get" context where the kernel's internal file_kattr
structure is initialized before calling vfs_fileattr_get(), we should
use the same mechanism when using fa.
[1]
BUG: KMSAN: uninit-value in fuse_fileattr_get+0xeb4/0x1450 fs/fuse/ioctl.c:517
fuse_fileattr_get+0xeb4/0x1450 fs/fuse/ioctl.c:517
vfs_fileattr_get fs/file_attr.c:94 [inline]
__do_sys_file_getattr fs/file_attr.c:416 [inline]
Local variable fa.i created at:
__do_sys_file_getattr fs/file_attr.c:380 [inline]
__se_sys_file_getattr+0x8c/0xbd0 fs/file_attr.c:372
Reported-by: syzbot+7c31755f2cea07838b0c@syzkaller.appspotmail.com
Closes: https://syzkaller.appspot.com/bug?extid=7c31755f2cea07838b0c
Tested-by: syzbot+7c31755f2cea07838b0c@syzkaller.appspotmail.com
Signed-off-by: Edward Adam Davis <eadavis@qq.com>
---
fs/file_attr.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/fs/file_attr.c b/fs/file_attr.c
index 13cdb31a3e94..4889cf59b256 100644
--- a/fs/file_attr.c
+++ b/fs/file_attr.c
@@ -377,7 +377,7 @@ SYSCALL_DEFINE5(file_getattr, int, dfd, const char __user *, filename,
struct filename *name __free(putname) = NULL;
unsigned int lookup_flags = 0;
struct file_attr fattr;
- struct file_kattr fa;
+ struct file_kattr fa = { .flags_valid = true }; /* hint only */
int error;
BUILD_BUG_ON(sizeof(struct file_attr) < FILE_ATTR_SIZE_VER0);
--
2.43.0
^ permalink raw reply related [flat|nested] 6+ messages in thread
end of thread, other threads:[~2026-02-06 6:53 UTC | newest]
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2026-02-06 3:37 [syzbot] [fuse?] KMSAN: uninit-value in fuse_fileattr_get syzbot
2026-02-06 3:46 ` Qing Wang
2026-02-06 4:16 ` syzbot
2026-02-06 6:00 ` Qing Wang
2026-02-06 6:53 ` syzbot
2026-02-06 6:20 ` [PATCH] fs: init flags_valid before calling vfs_fileattr_get Edward Adam Davis
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