KMSAN: uninit-value in vfat_rename2

syzbot syzbot 3 participants 4 messages Oct 3, 2024 – Oct 5, 2024

Subsystems (2)

VFS VFAT/FAT/msdos filesystem

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author syzbot

2024-10-03 23:45 UTC #0 lore raw

Hello,

syzbot found the following issue on:

HEAD commit:    e7ed34365879 Merge tag 'mailbox-v6.12' of git://git.kernel..
git tree:       upstream
console+strace: https://syzkaller.appspot.com/x/log.txt?x=11b54ea9980000
kernel config:  https://syzkaller.appspot.com/x/.config?x=92da5062b0d65389
dashboard link: https://syzkaller.appspot.com/bug?extid=ef0d7bc412553291aa86
compiler:       Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=14b7ed07980000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=101dfd9f980000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/66cc3d8c5c10/disk-e7ed3436.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/c7769a88b445/vmlinux-e7ed3436.xz
kernel image: https://storage.googleapis.com/syzbot-assets/c1fe4c6ee436/bzImage-e7ed3436.xz
mounted in repro #1: https://storage.googleapis.com/syzbot-assets/2ab98c65fd49/mount_0.gz
mounted in repro #2: https://storage.googleapis.com/syzbot-assets/7ffc0eb73060/mount_5.gz

IMPORTANT: if you fix the issue, please add the following tag to the commit:

Reported-by [email protected]

Buffer I/O error on dev loop4, logical block 34, lost sync page write FAT-fs (loop4): unable to read inode block for updating (i_pos 548)
=====================================================

BUG: KMSAN: uninit-value in vfat_rename fs/fat/namei_vfat.c:1038 [inline]
BUG: KMSAN: uninit-value in vfat_rename2+0x3dda/0x3de0 fs/fat/namei_vfat.c:1174
 vfat_rename fs/fat/namei_vfat.c:1038 [inline]
 vfat_rename2+0x3dda/0x3de0 fs/fat/namei_vfat.c:1174
 vfs_rename+0x1d9d/0x2280 fs/namei.c:5013
 do_renameat2+0x18cc/0x1d50 fs/namei.c:5170
 __do_sys_rename fs/namei.c:5217 [inline]
 __se_sys_rename fs/namei.c:5215 [inline]
 __x64_sys_rename+0xe8/0x140 fs/namei.c:5215
 x64_sys_call+0x1e4d/0x3ba0 arch/x86/include/generated/asm/syscalls_64.h:83
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xcd/0x1e0 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

Local variable sinfo.i created at:

 vfat_rename fs/fat/namei_vfat.c:937 [inline]
 vfat_rename2+0x124/0x3de0 fs/fat/namei_vfat.c:1174
 vfs_rename+0x1d9d/0x2280 fs/namei.c:5013

CPU: 1 UID: 0 PID: 5211 Comm: syz-executor818 Not tainted 6.11.0-syzkaller-12113-ge7ed34365879 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/13/2024
=====================================================

---
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If you want to undo deduplication, reply with:
#syz undup

OGAWA Hirofumi

maintainer

2024-10-04 06:28 UTC #1 lore raw

Quoted 20 lines · syzbot

Hello,
syzbot found the following issue on:
HEAD commit:    e7ed34365879 Merge tag 'mailbox-v6.12' of git://git.kernel..
git tree:       upstream
console+strace: https://syzkaller.appspot.com/x/log.txt?x=11b54ea9980000
kernel config:  https://syzkaller.appspot.com/x/.config?x=92da5062b0d65389
dashboard link: https://syzkaller.appspot.com/bug?extid=ef0d7bc412553291aa86
compiler:       Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=14b7ed07980000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=101dfd9f980000
Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/66cc3d8c5c10/disk-e7ed3436.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/c7769a88b445/vmlinux-e7ed3436.xz
kernel image: https://storage.googleapis.com/syzbot-assets/c1fe4c6ee436/bzImage-e7ed3436.xz
mounted in repro #1: https://storage.googleapis.com/syzbot-assets/2ab98c65fd49/mount_0.gz
mounted in repro #2: https://storage.googleapis.com/syzbot-assets/7ffc0eb73060/mount_5.gz

Quoted 2 lines

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by [email protected]

The patch fixes this bug. Please apply.
Thanks.

From: OGAWA Hirofumi <[email protected]>
Subject: [PATCH] fat: Fix uninitialized variable
Date: Fri, 04 Oct 2024 15:03:49 +0900

Reported-by [email protected]

Signed-off-by OGAWA Hirofumi <[email protected]>

---
 fs/fat/namei_vfat.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

fs/fat/namei_vfat.c +1 -1

index 6423e1d..15bf32c 100644
@@ -1037,7 +1037,7 @@ error_inode:
 	if (corrupt < 0) {
 		fat_fs_error(new_dir->i_sb,
 			     "%s: Filesystem corrupted (i_pos %lld)",
-			     __func__, sinfo.i_pos);
+			     __func__, new_i_pos);
 	}
 	goto out;
 }

Signature · 1 line

OGAWA Hirofumi <[email protected]>

Andrew Morton

2024-10-04 22:53 UTC #2 lore raw

Quoted 29 lines · On Fri, 04 Oct 2024 15:20:34 +0900 OGAWA Hirofumi…

Quoted 20 lines · syzbot
Hello,
syzbot found the following issue on:
HEAD commit:    e7ed34365879 Merge tag 'mailbox-v6.12' of git://git.kernel..
git tree:       upstream
console+strace: https://syzkaller.appspot.com/x/log.txt?x=11b54ea9980000
kernel config:  https://syzkaller.appspot.com/x/.config?x=92da5062b0d65389
dashboard link: https://syzkaller.appspot.com/bug?extid=ef0d7bc412553291aa86
compiler:       Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=14b7ed07980000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=101dfd9f980000
Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/66cc3d8c5c10/disk-e7ed3436.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/c7769a88b445/vmlinux-e7ed3436.xz
kernel image: https://storage.googleapis.com/syzbot-assets/c1fe4c6ee436/bzImage-e7ed3436.xz
mounted in repro #1: https://storage.googleapis.com/syzbot-assets/2ab98c65fd49/mount_0.gz
mounted in repro #2: https://storage.googleapis.com/syzbot-assets/7ffc0eb73060/mount_5.gz
Quoted 2 lines
IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by [email protected]
The patch fixes this bug. Please apply.
Thanks.

Quoted 6 lines

From: OGAWA Hirofumi <[email protected]>
Subject: [PATCH] fat: Fix uninitialized variable
Date: Fri, 04 Oct 2024 15:03:49 +0900
Reported-by [email protected]
Signed-off-by OGAWA Hirofumi <[email protected]>

Could we please have some description? Seems that an IO error triggers this?

OGAWA Hirofumi

maintainer

2024-10-05 05:50 UTC #3 lore raw

Quoted 11 lines · Andrew Morton

Quoted 9 lines · On Fri, 04 Oct 2024 15:20:34 +0900 OGAWA Hirofumi…
Quoted 7 lines · syzbot
git tree: upstream
console+strace: https://syzkaller.appspot.com/x/log.txt?x=11b54ea9980000
kernel config:  https://syzkaller.appspot.com/x/.config?x=92da5062b0d65389
dashboard link: https://syzkaller.appspot.com/bug?extid=ef0d7bc412553291aa86
compiler:       Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=14b7ed07980000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=101dfd9f980000

[...]

Quoted 7 lines

Quoted 7 lines
Quoted 2 lines
IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by [email protected]
The patch fixes this bug. Please apply.
Thanks.

Quoted 8 lines

Quoted 6 lines
From: OGAWA Hirofumi <[email protected]>
Subject: [PATCH] fat: Fix uninitialized variable
Date: Fri, 04 Oct 2024 15:03:49 +0900
Reported-by [email protected]
Signed-off-by OGAWA Hirofumi <[email protected]>
Could we please have some description? Seems that an IO error triggers this?

OK, I added the description guessed from syzbot log.

Thanks.

From: OGAWA Hirofumi <[email protected]>
Subject: [PATCH v2] fat: Fix uninitialized variable
Date: Fri, 04 Oct 2024 15:03:49 +0900

This produced by corrupted fs image of syzbot, in theory, however IO error would trigger this too.

This affects just a error report, so should not be serious error.

Reported-by [email protected]

Signed-off-by OGAWA Hirofumi <[email protected]>

---
 fs/fat/namei_vfat.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

fs/fat/namei_vfat.c +1 -1

index 6423e1d..15bf32c 100644
@@ -1037,7 +1037,7 @@ error_inode:
 	if (corrupt < 0) {
 		fat_fs_error(new_dir->i_sb,
 			     "%s: Filesystem corrupted (i_pos %lld)",
-			     __func__, sinfo.i_pos);
+			     __func__, new_i_pos);
 	}
 	goto out;
 }

Signature · 1 line

OGAWA Hirofumi <[email protected]>