[syzbot] [jfs?] kernel BUG in jfs_truncate_nolock

[syzbot] [jfs?] kernel BUG in jfs_truncate_nolock

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit:    f66bc387efbe Merge tag 'scsi-misc' of git://git.kernel.org..
git tree:       upstream
console+strace: https://syzkaller.appspot.com/x/log.txt?x=14ccbff4580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=5035170c334b10e0
dashboard link: https://syzkaller.appspot.com/bug?extid=630f6d40b3ccabc8e96e
compiler:       Debian clang version 20.1.6 (++20250514063057+1e4d39e07757-1~exp1~20250514183223.118), Debian LLD 20.1.6
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=1725f7f4580000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=158147f4580000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/fd515d0ab520/disk-f66bc387.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/02091b462a17/vmlinux-f66bc387.xz
kernel image: https://storage.googleapis.com/syzbot-assets/963425e89030/bzImage-f66bc387.xz
mounted in repro: https://storage.googleapis.com/syzbot-assets/41b7b3dad955/mount_0.gz
  fsck result: failed (log: https://syzkaller.appspot.com/x/fsck.log?x=10a93482580000)

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+630f6d40b3ccabc8e96e@syzkaller.appspotmail.com

loop0: detected capacity change from 0 to 32768
BUG at fs/jfs/inode.c:370 assert(length >= 0)
------------[ cut here ]------------
kernel BUG at fs/jfs/inode.c:370!
Oops: invalid opcode: 0000 [#1] SMP KASAN PTI
CPU: 1 UID: 0 PID: 5823 Comm: syz-executor203 Not tainted 6.15.0-syzkaller-08486-gf66bc387efbe #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025
RIP: 0010:jfs_truncate_nolock+0x33b/0x340 fs/jfs/inode.c:370
Code: e8 aa a9 25 08 e8 25 01 89 fe 48 c7 c7 80 6f c3 8b 48 c7 c6 a0 6b c3 8b ba 72 01 00 00 48 c7 c1 c0 6f c3 8b e8 76 4f f0 fd 90 <0f> 0b 0f 1f 00 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 66
RSP: 0018:ffffc900043af860 EFLAGS: 00010246
RAX: 000000000000002d RBX: ffff8880770d1fd8 RCX: 6cc80c570e63f800
RDX: 0000000000000000 RSI: 0000000080000000 RDI: 0000000000000000
RBP: ffffc900043af910 R08: ffffc900043af547 R09: 1ffff92000875ea8
R10: dffffc0000000000 R11: fffff52000875ea9 R12: fffffa000000000a
R13: dffffc0000000000 R14: ffff8880770d1fd8 R15: 1ffff92000875f10
FS:  0000555593cd0380(0000) GS:ffff888125d98000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fd7dd58a000 CR3: 00000000338e4000 CR4: 00000000003526f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <TASK>
 jfs_truncate fs/jfs/inode.c:412 [inline]
 jfs_write_failed+0x119/0x190 fs/jfs/inode.c:289
 jfs_direct_IO+0x1f4/0x220 fs/jfs/inode.c:342
 generic_file_direct_write+0x1d8/0x3e0 mm/filemap.c:4037
 __generic_file_write_iter+0x11d/0x230 mm/filemap.c:4206
 generic_file_write_iter+0x10f/0x540 mm/filemap.c:4246
 new_sync_write fs/read_write.c:593 [inline]
 vfs_write+0x548/0xa90 fs/read_write.c:686
 ksys_write+0x145/0x250 fs/read_write.c:738
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xfa/0x3b0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fce1ba0eb99
Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 f1 17 00 00 90 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 b8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007ffd0e6719b8 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007fce1ba0eb99
RDX: 00000000000000a0 RSI: 0000200000000340 RDI: 0000000000000004
RBP: 00007fce1ba875f0 R08: 0000000000000000 R09: 0000555593cd14c0
R10: 0000000000000000 R11: 0000000000000246 R12: 00007ffd0e6719e0
R13: 00007ffd0e671c08 R14: 431bde82d7b634db R15: 00007fce1ba5703b
 </TASK>
Modules linked in:
---[ end trace 0000000000000000 ]---
RIP: 0010:jfs_truncate_nolock+0x33b/0x340 fs/jfs/inode.c:370
Code: e8 aa a9 25 08 e8 25 01 89 fe 48 c7 c7 80 6f c3 8b 48 c7 c6 a0 6b c3 8b ba 72 01 00 00 48 c7 c1 c0 6f c3 8b e8 76 4f f0 fd 90 <0f> 0b 0f 1f 00 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 66
RSP: 0018:ffffc900043af860 EFLAGS: 00010246
RAX: 000000000000002d RBX: ffff8880770d1fd8 RCX: 6cc80c570e63f800
RDX: 0000000000000000 RSI: 0000000080000000 RDI: 0000000000000000
RBP: ffffc900043af910 R08: ffffc900043af547 R09: 1ffff92000875ea8
R10: dffffc0000000000 R11: fffff52000875ea9 R12: fffffa000000000a
R13: dffffc0000000000 R14: ffff8880770d1fd8 R15: 1ffff92000875f10
FS:  0000555593cd0380(0000) GS:ffff888125c98000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000055923e290368 CR3: 00000000338e4000 CR4: 00000000003526f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400


---
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Re: [syzbot] [jfs?] kernel BUG in jfs_truncate_nolock

[Edward Adam Davis]

#syz test

diff --git a/fs/jfs/file.c b/fs/jfs/file.c
index 01b6912e60f8..742cadd1f37e 100644
--- a/fs/jfs/file.c
+++ b/fs/jfs/file.c
@@ -44,6 +44,9 @@ static int jfs_open(struct inode *inode, struct file *file)
 {
 	int rc;
 
+	if (S_ISREG(inode->i_mode) && inode->i_size < 0)
+		return -EIO;
+
 	if ((rc = dquot_file_open(inode, file)))
 		return rc;
 

Re: [syzbot] [jfs?] kernel BUG in jfs_truncate_nolock

[syzbot]

Hello,

syzbot has tested the proposed patch and the reproducer did not trigger any issue:

Reported-by: syzbot+630f6d40b3ccabc8e96e@syzkaller.appspotmail.com
Tested-by: syzbot+630f6d40b3ccabc8e96e@syzkaller.appspotmail.com

Tested on:

commit:         5abc7438 Merge tag 'nfs-for-6.16-1' of git://git.linux..
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=1673bc82580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=82e79780b034d72f
dashboard link: https://syzkaller.appspot.com/bug?extid=630f6d40b3ccabc8e96e
compiler:       Debian clang version 20.1.6 (++20250514063057+1e4d39e07757-1~exp1~20250514183223.118), Debian LLD 20.1.6
patch:          https://syzkaller.appspot.com/x/patch.diff?x=15f3140c580000

Note: testing is done by a robot and is best-effort only.

[PATCH] jfs: Regular file curruption check

[Edward Adam Davis]

The reproducer builds a corrupted file on disk with a negative i_size value.
Add a check when opening this file to avoid subsequent operation failures.

Reported-by: syzbot+630f6d40b3ccabc8e96e@syzkaller.appspotmail.com
Closes: https://syzkaller.appspot.com/bug?extid=630f6d40b3ccabc8e96e
Tested-by: syzbot+630f6d40b3ccabc8e96e@syzkaller.appspotmail.com
Signed-off-by: Edward Adam Davis <eadavis@qq.com>
---
 fs/jfs/file.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/fs/jfs/file.c b/fs/jfs/file.c
index 01b6912e60f8..742cadd1f37e 100644
--- a/fs/jfs/file.c
+++ b/fs/jfs/file.c
@@ -44,6 +44,9 @@ static int jfs_open(struct inode *inode, struct file *file)
 {
 	int rc;
 
+	if (S_ISREG(inode->i_mode) && inode->i_size < 0)
+		return -EIO;
+
 	if ((rc = dquot_file_open(inode, file)))
 		return rc;
 
-- 
2.43.0

Re: [syzbot] #syz test https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git 5abc7438f1e9d62e91ad775cc83c9594c48d2282

[syzbot]

For archival purposes, forwarding an incoming command email to
linux-kernel@vger.kernel.org, syzkaller-bugs@googlegroups.com.

***

Subject: #syz test https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git 5abc7438f1e9d62e91ad775cc83c9594c48d2282
Author: dmantipov@yandex.ru

#syz test https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git 5abc7438f1e9d62e91ad775cc83c9594c48d2282

Re: [PATCH] jfs: Regular file curruption check

[Dave Kleikamp]

On 6/4/25 1:48AM, Edward Adam Davis wrote:
> The reproducer builds a corrupted file on disk with a negative i_size value.
> Add a check when opening this file to avoid subsequent operation failures.

Looks good. I'll apply and test this.

Thanks,
Shaggy

> 
> Reported-by: syzbot+630f6d40b3ccabc8e96e@syzkaller.appspotmail.com
> Closes: https://syzkaller.appspot.com/bug?extid=630f6d40b3ccabc8e96e
> Tested-by: syzbot+630f6d40b3ccabc8e96e@syzkaller.appspotmail.com
> Signed-off-by: Edward Adam Davis <eadavis@qq.com>
> ---
>   fs/jfs/file.c | 3 +++
>   1 file changed, 3 insertions(+)
> 
> diff --git a/fs/jfs/file.c b/fs/jfs/file.c
> index 01b6912e60f8..742cadd1f37e 100644
> --- a/fs/jfs/file.c
> +++ b/fs/jfs/file.c
> @@ -44,6 +44,9 @@ static int jfs_open(struct inode *inode, struct file *file)
>   {
>   	int rc;
>   
> +	if (S_ISREG(inode->i_mode) && inode->i_size < 0)
> +		return -EIO;
> +
>   	if ((rc = dquot_file_open(inode, file)))
>   		return rc;
>