[syzbot] [jfs?] UBSAN: shift-out-of-bounds in dbJoin (2)

[syzbot] [jfs?] UBSAN: shift-out-of-bounds in dbJoin (2)

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit:    4a26e7032d7d Merge tag 'core-bugs-2025-12-01' of git://git..
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=11ea9512580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=dd808c444ce84c8
dashboard link: https://syzkaller.appspot.com/bug?extid=fa603ae6b02658401ca7
compiler:       Debian clang version 20.1.8 (++20250708063551+0c9f909b7976-1~exp1~20250708183702.136), Debian LLD 20.1.8
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=14dbe192580000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=112d92b4580000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/a40b77c72522/disk-4a26e703.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/b2b4fa9b2036/vmlinux-4a26e703.xz
kernel image: https://storage.googleapis.com/syzbot-assets/7105f0502b78/bzImage-4a26e703.xz
mounted in repro: https://storage.googleapis.com/syzbot-assets/1f7c2e37ce13/mount_0.gz
  fsck result: failed (log: https://syzkaller.appspot.com/x/fsck.log?x=170ab512580000)

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+fa603ae6b02658401ca7@syzkaller.appspotmail.com

------------[ cut here ]------------
UBSAN: shift-out-of-bounds in fs/jfs/jfs_dmap.c:2795:11
shift exponent 132 is too large for 32-bit type 'int'
CPU: 0 UID: 0 PID: 123 Comm: jfsCommit Not tainted syzkaller #0 PREEMPT_{RT,(full)} 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025
Call Trace:
 <TASK>
 dump_stack_lvl+0x189/0x250 lib/dump_stack.c:120
 ubsan_epilogue+0xa/0x40 lib/ubsan.c:233
 __ubsan_handle_shift_out_of_bounds+0x386/0x410 lib/ubsan.c:494
 dbJoin+0x2dc/0x300 fs/jfs/jfs_dmap.c:2795
 dbFreeBits+0x4e1/0xdb0 fs/jfs/jfs_dmap.c:2340
 dbFreeDmap fs/jfs/jfs_dmap.c:2089 [inline]
 dbFree+0x336/0x650 fs/jfs/jfs_dmap.c:398
 txFreeMap+0x7ff/0xde0 fs/jfs/jfs_txnmgr.c:2535
 txUpdateMap+0x308/0x9c0 fs/jfs/jfs_txnmgr.c:-1
 txLazyCommit fs/jfs/jfs_txnmgr.c:2665 [inline]
 jfs_lazycommit+0x3f1/0xa10 fs/jfs/jfs_txnmgr.c:2734
 kthread+0x711/0x8a0 kernel/kthread.c:463
 ret_from_fork+0x52d/0xa60 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
 </TASK>
---[ end trace ]---
Kernel panic - not syncing: UBSAN: panic_on_warn set ...
CPU: 0 UID: 0 PID: 123 Comm: jfsCommit Not tainted syzkaller #0 PREEMPT_{RT,(full)} 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025
Call Trace:
 <TASK>
 dump_stack_lvl+0x99/0x250 lib/dump_stack.c:120
 vpanic+0x237/0x6d0 kernel/panic.c:489
 panic+0xb9/0xc0 kernel/panic.c:626
 check_panic_on_warn+0x89/0xb0 kernel/panic.c:376
 __ubsan_handle_shift_out_of_bounds+0x386/0x410 lib/ubsan.c:494
 dbJoin+0x2dc/0x300 fs/jfs/jfs_dmap.c:2795
 dbFreeBits+0x4e1/0xdb0 fs/jfs/jfs_dmap.c:2340
 dbFreeDmap fs/jfs/jfs_dmap.c:2089 [inline]
 dbFree+0x336/0x650 fs/jfs/jfs_dmap.c:398
 txFreeMap+0x7ff/0xde0 fs/jfs/jfs_txnmgr.c:2535
 txUpdateMap+0x308/0x9c0 fs/jfs/jfs_txnmgr.c:-1
 txLazyCommit fs/jfs/jfs_txnmgr.c:2665 [inline]
 jfs_lazycommit+0x3f1/0xa10 fs/jfs/jfs_txnmgr.c:2734
 kthread+0x711/0x8a0 kernel/kthread.c:463
 ret_from_fork+0x52d/0xa60 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
 </TASK>
Kernel Offset: disabled


---
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If the report is already addressed, let syzbot know by replying with:
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If you want syzbot to run the reproducer, reply with:
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#syz undup

Re: [syzbot] [jfs?] UBSAN: shift-out-of-bounds in dbJoin (2)

[Edward Adam Davis]

#syz test

diff --git a/fs/jfs/jfs_dmap.c b/fs/jfs/jfs_dmap.c
index cdfa699cd7c8..7c35e69cafb9 100644
--- a/fs/jfs/jfs_dmap.c
+++ b/fs/jfs/jfs_dmap.c
@@ -2291,6 +2291,8 @@ static int dbFreeBits(struct bmap * bmp, struct dmap * dp, s64 blkno,
 	int rc = 0;
 	int size;
 
+	if (tp->dmt_budmin < 0)
+		return -EUCLEAN;
 	/* determine the bit number and word within the dmap of the
 	 * starting block.
 	 */

Re: [syzbot] [jfs?] UBSAN: shift-out-of-bounds in dbJoin (2)

[syzbot]

Hello,

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

Reported-by: syzbot+fa603ae6b02658401ca7@syzkaller.appspotmail.com
Tested-by: syzbot+fa603ae6b02658401ca7@syzkaller.appspotmail.com

Tested on:

commit:         37bb2e72 Merge tag 'staging-6.19-rc1' of git://git.ker..
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=135f26c2580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=34836e56fe7fb6c8
dashboard link: https://syzkaller.appspot.com/bug?extid=fa603ae6b02658401ca7
compiler:       Debian clang version 20.1.8 (++20250708063551+0c9f909b7976-1~exp1~20250708183702.136), Debian LLD 20.1.8
patch:          https://syzkaller.appspot.com/x/patch.diff?x=145726c2580000

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

[PATCH] jfs: Add a sanity check for budmin

[Edward Adam Davis]

In a corrupted file system image, the budmin value is less than 0,
which causes the lazycommit thread to report an out-of-bounds error
when retrieving the buddy size in dbJoin [1].

Add a check for potentially negative budmin to avoid the problem in [1].

[1]
UBSAN: shift-out-of-bounds in fs/jfs/jfs_dmap.c:2795:11
shift exponent 132 is too large for 32-bit type 'int'
Call Trace:
 dbJoin+0x2dc/0x300 fs/jfs/jfs_dmap.c:2795
 dbFreeBits+0x4e1/0xdb0 fs/jfs/jfs_dmap.c:2340
 dbFreeDmap fs/jfs/jfs_dmap.c:2089 [inline]
 dbFree+0x336/0x650 fs/jfs/jfs_dmap.c:398
 txFreeMap+0x7ff/0xde0 fs/jfs/jfs_txnmgr.c:2535
 txUpdateMap+0x308/0x9c0 fs/jfs/jfs_txnmgr.c:-1
 txLazyCommit fs/jfs/jfs_txnmgr.c:2665 [inline]
 jfs_lazycommit+0x3f1/0xa10 fs/jfs/jfs_txnmgr.c:2734

Reported-by: syzbot+fa603ae6b02658401ca7@syzkaller.appspotmail.com
Closes: https://syzkaller.appspot.com/bug?extid=fa603ae6b02658401ca7
Tested-by: syzbot+fa603ae6b02658401ca7@syzkaller.appspotmail.com
Signed-off-by: Edward Adam Davis <eadavis@qq.com>
---
 fs/jfs/jfs_dmap.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/fs/jfs/jfs_dmap.c b/fs/jfs/jfs_dmap.c
index cdfa699cd7c8..8f8084756e32 100644
--- a/fs/jfs/jfs_dmap.c
+++ b/fs/jfs/jfs_dmap.c
@@ -2291,6 +2291,8 @@ static int dbFreeBits(struct bmap * bmp, struct dmap * dp, s64 blkno,
 	int rc = 0;
 	int size;
 
+	if (tp->dmt_budmin < 0)
+		return -EUCLEAN;
 	/* determine the bit number and word within the dmap of the
 	 * starting block.
 	 */
-- 
2.43.0

Forwarded: [PATCH] jfs: fix shift-out-of-bounds in dbJoin

[syzbot]

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

***

Subject: [PATCH] jfs: fix shift-out-of-bounds in dbJoin
Author: tristmd@gmail.com

From: Tristan Madani <tristan@talencesecurity.com>

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


dbJoin() computes a buddy size via BUDSIZE(newval, budmin), which
expands to 1 << (newval - budmin).  If the on-disk tree metadata is
corrupted such that the leaf values or free counts are inconsistent,
newval can exceed budmin + 31, causing a shift-out-of-bounds:

  UBSAN: shift-out-of-bounds in fs/jfs/jfs_dmap.c:2882:11
  shift exponent 132 is too large for 32-bit type 'int'

The maximum meaningful newval for a given tree is budmin + l2nleafs,
since BUDSIZE at that point equals nleafs and the while loop would not
execute.  Any value beyond that indicates corrupted metadata.

Add a sanity check before the BUDSIZE call: if newval exceeds
budmin + l2nleafs, return -EIO.

Reported-by: syzbot+fa603ae6b02658401ca7@syzkaller.appspotmail.com
Closes: https://syzkaller.appspot.com/bug?extid=fa603ae6b02658401ca7
Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
Cc: stable@vger.kernel.org
Signed-off-by: Tristan Madani <tristan@talencesecurity.com>
---
 fs/jfs/jfs_dmap.c | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/fs/jfs/jfs_dmap.c b/fs/jfs/jfs_dmap.c
index XXXXXXX..XXXXXXX 100644
--- a/fs/jfs/jfs_dmap.c
+++ b/fs/jfs/jfs_dmap.c
@@ -2864,6 +2864,14 @@ static int dbJoin(dmtree_t *tp, int leafno, int newval, bool is_ctl)
 	if (newval >= tp->dmt_budmin) {
 		/* pickup a pointer to the leaves of the tree.
 		 */
+
+		/* Validate newval to prevent shift-out-of-bounds in
+		 * BUDSIZE.  The maximum meaningful value is budmin +
+		 * l2nleafs; anything beyond indicates corrupted metadata.
+		 */
+		if (newval > tp->dmt_budmin +
+		    le32_to_cpu(tp->dmt_l2nleafs))
+			return -EIO;
 		leaf = tp->dmt_stree + le32_to_cpu(tp->dmt_leafidx);

 		/* try to join the specified leaf into a large binary
--
2.39.5

Re: [syzbot] [jfs?] UBSAN: shift-out-of-bounds in dbJoin (2)

[syzbot]

Hello,

syzbot has tested the proposed patch but the reproducer is still triggering an issue:
UBSAN: shift-out-of-bounds in dbJoin

------------[ cut here ]------------
UBSAN: shift-out-of-bounds in fs/jfs/jfs_dmap.c:2890:11
shift exponent 132 is too large for 32-bit type 'int'
CPU: 1 UID: 0 PID: 127 Comm: jfsCommit Not tainted syzkaller #0 PREEMPT_{RT,(full)} 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/18/2026
Call Trace:
 <TASK>
 dump_stack_lvl+0xe8/0x150 lib/dump_stack.c:120
 ubsan_epilogue+0xa/0x30 lib/ubsan.c:233
 __ubsan_handle_shift_out_of_bounds+0x385/0x410 lib/ubsan.c:494
 dbJoin+0x34f/0x380 fs/jfs/jfs_dmap.c:2890
 dbFreeBits+0x4e1/0xdb0 fs/jfs/jfs_dmap.c:2427
 dbFreeDmap fs/jfs/jfs_dmap.c:2176 [inline]
 dbFree+0x336/0x650 fs/jfs/jfs_dmap.c:485
 txFreeMap+0x7ff/0xde0 fs/jfs/jfs_txnmgr.c:2536
 txUpdateMap+0x308/0x9c0 fs/jfs/jfs_txnmgr.c:-1
 txLazyCommit fs/jfs/jfs_txnmgr.c:2666 [inline]
 jfs_lazycommit+0x3ef/0xa10 fs/jfs/jfs_txnmgr.c:2735
 kthread+0x388/0x470 kernel/kthread.c:436
 ret_from_fork+0x514/0xb70 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
 </TASK>
---[ end trace ]---
Kernel panic - not syncing: UBSAN: panic_on_warn set ...
CPU: 1 UID: 0 PID: 127 Comm: jfsCommit Not tainted syzkaller #0 PREEMPT_{RT,(full)} 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/18/2026
Call Trace:
 <TASK>
 vpanic+0x56c/0xa60 kernel/panic.c:650
 panic+0xc5/0xd0 kernel/panic.c:787
 check_panic_on_warn+0x89/0xb0 kernel/panic.c:524
 __ubsan_handle_shift_out_of_bounds+0x385/0x410 lib/ubsan.c:494
 dbJoin+0x34f/0x380 fs/jfs/jfs_dmap.c:2890
 dbFreeBits+0x4e1/0xdb0 fs/jfs/jfs_dmap.c:2427
 dbFreeDmap fs/jfs/jfs_dmap.c:2176 [inline]
 dbFree+0x336/0x650 fs/jfs/jfs_dmap.c:485
 txFreeMap+0x7ff/0xde0 fs/jfs/jfs_txnmgr.c:2536
 txUpdateMap+0x308/0x9c0 fs/jfs/jfs_txnmgr.c:-1
 txLazyCommit fs/jfs/jfs_txnmgr.c:2666 [inline]
 jfs_lazycommit+0x3ef/0xa10 fs/jfs/jfs_txnmgr.c:2735
 kthread+0x388/0x470 kernel/kthread.c:436
 ret_from_fork+0x514/0xb70 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
 </TASK>
Kernel Offset: disabled


Tested on:

commit:         43cfbdda Merge tag 'for-linus-iommufd' of git://git.ke..
git tree:       https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master
console output: https://syzkaller.appspot.com/x/log.txt?x=1115f036580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=4bcfdf96e3f779b1
dashboard link: https://syzkaller.appspot.com/bug?extid=fa603ae6b02658401ca7
compiler:       Debian clang version 21.1.8 (++20251221033036+2078da43e25a-1~exp1~20251221153213.50), Debian LLD 21.1.8
patch:          https://syzkaller.appspot.com/x/patch.diff?x=16f70fca580000

Forwarded: Re: [syzbot] UBSAN: shift-out-of-bounds in dbJoin

[syzbot]

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

***

Subject: Re: [syzbot] UBSAN: shift-out-of-bounds in dbJoin
Author: tristmd@gmail.com

#syz test: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master
>From b3eba06211261ff42d58377c02b45bf48aae8f82 Mon Sep 17 00:00:00 2001
From: Tristan Madani <tristan@talencesecurity.com>
Date: Fri, 17 Apr 2026 16:15:14 +0000
Subject: [PATCH] jfs: fix shift-out-of-bounds in dbJoin
dbJoin() can receive a corrupted newval from on-disk metadata that
exceeds the valid range for the BUDSIZE macro's shift operation.
When newval is larger than budmin + l2nleafs, the shift produces
undefined behavior detected by UBSAN.
Add a sanity check on newval before the shift to reject corrupted
values.
Reported-by: syzbot+fa603ae6b02658401ca7@syzkaller.appspotmail.com
Closes: https://syzkaller.appspot.com/bug?extid=fa603ae6b02658401ca7
Signed-off-by: Tristan Madani <tristan@talencesecurity.com>
---
 fs/jfs/jfs_dmap.c | 3 +++
 1 file changed, 3 insertions(+)
diff --git a/fs/jfs/jfs_dmap.c b/fs/jfs/jfs_dmap.c
index a841cf2..4ad9b34 100644
--- a/fs/jfs/jfs_dmap.c
+++ b/fs/jfs/jfs_dmap.c
@@ -2864,6 +2864,9 @@ static int dbJoin(dmtree_t *tp, int leafno, int newval, bool is_ctl)
 	if (newval >= tp->dmt_budmin) {
 		/* pickup a pointer to the leaves of the tree.
 		 */
+		if (newval > tp->dmt_budmin +
+		    le32_to_cpu(tp->dmt_l2nleafs))
+			return -EIO;
 		leaf = tp->dmt_stree + le32_to_cpu(tp->dmt_leafidx);
 
 		/* try to join the specified leaf into a large binary
-- 
2.47.3

Re: [syzbot] [jfs?] UBSAN: shift-out-of-bounds in dbJoin (2)

[syzbot]

Hello,

syzbot has tested the proposed patch but the reproducer is still triggering an issue:
UBSAN: shift-out-of-bounds in dbJoin

------------[ cut here ]------------
UBSAN: shift-out-of-bounds in fs/jfs/jfs_dmap.c:2885:11
shift exponent 132 is too large for 32-bit type 'int'
CPU: 0 UID: 0 PID: 128 Comm: jfsCommit Not tainted syzkaller #0 PREEMPT_{RT,(full)} 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/18/2026
Call Trace:
 <TASK>
 dump_stack_lvl+0xe8/0x150 lib/dump_stack.c:120
 ubsan_epilogue+0xa/0x30 lib/ubsan.c:233
 __ubsan_handle_shift_out_of_bounds+0x385/0x410 lib/ubsan.c:494
 dbJoin+0x34f/0x380 fs/jfs/jfs_dmap.c:2885
 dbFreeBits+0x4e1/0xdb0 fs/jfs/jfs_dmap.c:2427
 dbFreeDmap fs/jfs/jfs_dmap.c:2176 [inline]
 dbFree+0x336/0x650 fs/jfs/jfs_dmap.c:485
 txFreeMap+0x7ff/0xde0 fs/jfs/jfs_txnmgr.c:2536
 txUpdateMap+0x308/0x9c0 fs/jfs/jfs_txnmgr.c:-1
 txLazyCommit fs/jfs/jfs_txnmgr.c:2666 [inline]
 jfs_lazycommit+0x3ef/0xa10 fs/jfs/jfs_txnmgr.c:2735
 kthread+0x388/0x470 kernel/kthread.c:436
 ret_from_fork+0x514/0xb70 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
 </TASK>
---[ end trace ]---
Kernel panic - not syncing: UBSAN: panic_on_warn set ...
CPU: 0 UID: 0 PID: 128 Comm: jfsCommit Not tainted syzkaller #0 PREEMPT_{RT,(full)} 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/18/2026
Call Trace:
 <TASK>
 vpanic+0x56c/0xa60 kernel/panic.c:650
 panic+0xc5/0xd0 kernel/panic.c:787
 check_panic_on_warn+0x89/0xb0 kernel/panic.c:524
 __ubsan_handle_shift_out_of_bounds+0x385/0x410 lib/ubsan.c:494
 dbJoin+0x34f/0x380 fs/jfs/jfs_dmap.c:2885
 dbFreeBits+0x4e1/0xdb0 fs/jfs/jfs_dmap.c:2427
 dbFreeDmap fs/jfs/jfs_dmap.c:2176 [inline]
 dbFree+0x336/0x650 fs/jfs/jfs_dmap.c:485
 txFreeMap+0x7ff/0xde0 fs/jfs/jfs_txnmgr.c:2536
 txUpdateMap+0x308/0x9c0 fs/jfs/jfs_txnmgr.c:-1
 txLazyCommit fs/jfs/jfs_txnmgr.c:2666 [inline]
 jfs_lazycommit+0x3ef/0xa10 fs/jfs/jfs_txnmgr.c:2735
 kthread+0x388/0x470 kernel/kthread.c:436
 ret_from_fork+0x514/0xb70 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
 </TASK>
Kernel Offset: disabled


Tested on:

commit:         d730905b Merge tag 'mips_7.1' of git://git.kernel.org/..
git tree:       https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master
console output: https://syzkaller.appspot.com/x/log.txt?x=16e2a4ce580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=4bcfdf96e3f779b1
dashboard link: https://syzkaller.appspot.com/bug?extid=fa603ae6b02658401ca7
compiler:       Debian clang version 21.1.8 (++20251221033036+2078da43e25a-1~exp1~20251221153213.50), Debian LLD 21.1.8
patch:          https://syzkaller.appspot.com/x/patch.diff?x=15ea1906580000

Forwarded: Re: [syzbot] [jfs?] UBSAN: shift-out-of-bounds in dbJoin (2)

[syzbot]

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

***

Subject: Re: [syzbot] [jfs?] UBSAN: shift-out-of-bounds in dbJoin (2)
Author: tristmd@gmail.com

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

diff --git a/fs/jfs/jfs_dmap.c b/fs/jfs/jfs_dmap.c
index XXXXXXX..XXXXXXX 100644
--- a/fs/jfs/jfs_dmap.c
+++ b/fs/jfs/jfs_dmap.c
@@ -2770,6 +2770,10 @@ static int dbJoin(dmtree_t *tp, int leafno, int newval, bool is_ctl)
 	int budsz, buddy;
 	s8 *leaf;
 
+	if (newval < 0 ||
+	    (newval >= tp->dmt_budmin && newval - tp->dmt_budmin >= 32))
+		return -EIO;
+
 	/* can the new leaf value require a join with other leaves ?
 	 */
 	if (newval >= tp->dmt_budmin) {

Re: [syzbot] [jfs?] UBSAN: shift-out-of-bounds in dbJoin (2)

[syzbot]

Hello,

syzbot has tested the proposed patch but the reproducer is still triggering an issue:
KASAN: slab-use-after-free Read in lbmIODone

==================================================================
BUG: KASAN: slab-use-after-free in lbmIODone+0x1312/0x16c0 fs/jfs/jfs_logmgr.c:2192
Read of size 4 at addr ffff88801b6c1808 by task ksoftirqd/0/15

CPU: 0 UID: 0 PID: 15 Comm: ksoftirqd/0 Not tainted syzkaller #0 PREEMPT_{RT,(full)} 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/18/2026
Call Trace:
 <TASK>
 dump_stack_lvl+0xe8/0x150 lib/dump_stack.c:120
 print_address_description+0x55/0x1e0 mm/kasan/report.c:378
 print_report+0x58/0x70 mm/kasan/report.c:482
 kasan_report+0x117/0x150 mm/kasan/report.c:595
 lbmIODone+0x1312/0x16c0 fs/jfs/jfs_logmgr.c:2192
 blk_update_request+0x57e/0xe60 block/blk-mq.c:1016
 blk_mq_end_request+0x3e/0x70 block/blk-mq.c:1178
 blk_complete_reqs block/blk-mq.c:1253 [inline]
 blk_done_softirq+0x10a/0x160 block/blk-mq.c:1258
 handle_softirqs+0x1de/0x6d0 kernel/softirq.c:622
 run_ksoftirqd+0x52/0x180 kernel/softirq.c:1076
 smpboot_thread_fn+0x541/0xa50 kernel/smpboot.c:160
 kthread+0x388/0x470 kernel/kthread.c:436
 ret_from_fork+0x514/0xb70 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
 </TASK>

Allocated by task 6772:
 kasan_save_stack mm/kasan/common.c:57 [inline]
 kasan_save_track+0x3e/0x80 mm/kasan/common.c:78
 poison_kmalloc_redzone mm/kasan/common.c:398 [inline]
 __kasan_kmalloc+0x93/0xb0 mm/kasan/common.c:415
 kasan_kmalloc include/linux/kasan.h:263 [inline]
 __kmalloc_cache_noprof+0x3a6/0x690 mm/slub.c:5415
 kmalloc_noprof include/linux/slab.h:950 [inline]
 lbmLogInit fs/jfs/jfs_logmgr.c:1819 [inline]
 lmLogInit+0x3e5/0x1a00 fs/jfs/jfs_logmgr.c:1267
 open_inline_log fs/jfs/jfs_logmgr.c:1173 [inline]
 lmLogOpen+0x4e1/0xfa0 fs/jfs/jfs_logmgr.c:1067
 jfs_mount_rw+0xee/0x670 fs/jfs/jfs_mount.c:257
 jfs_fill_super+0x754/0xd80 fs/jfs/super.c:532
 get_tree_bdev_flags+0x431/0x4f0 fs/super.c:1694
 vfs_get_tree+0x92/0x2a0 fs/super.c:1754
 fc_mount fs/namespace.c:1193 [inline]
 do_new_mount_fc fs/namespace.c:3758 [inline]
 do_new_mount+0x341/0xd30 fs/namespace.c:3834
 do_mount fs/namespace.c:4167 [inline]
 __do_sys_mount fs/namespace.c:4383 [inline]
 __se_sys_mount+0x31d/0x420 fs/namespace.c:4360
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x15f/0xf80 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

Freed by task 6607:
 kasan_save_stack mm/kasan/common.c:57 [inline]
 kasan_save_track+0x3e/0x80 mm/kasan/common.c:78
 kasan_save_free_info+0x46/0x50 mm/kasan/generic.c:584
 poison_slab_object mm/kasan/common.c:253 [inline]
 __kasan_slab_free+0x5c/0x80 mm/kasan/common.c:285
 kasan_slab_free include/linux/kasan.h:235 [inline]
 slab_free_hook mm/slub.c:2689 [inline]
 slab_free mm/slub.c:6246 [inline]
 kfree+0x1c5/0x6c0 mm/slub.c:6561
 lbmLogShutdown fs/jfs/jfs_logmgr.c:1862 [inline]
 lmLogShutdown+0x456/0x850 fs/jfs/jfs_logmgr.c:1681
 lmLogClose+0x28a/0x520 fs/jfs/jfs_logmgr.c:1457
 jfs_umount+0x2fb/0x3d0 fs/jfs/jfs_umount.c:124
 jfs_put_super+0x8c/0x190 fs/jfs/super.c:194
 generic_shutdown_super+0x13d/0x2d0 fs/super.c:646
 kill_block_super+0x44/0x90 fs/super.c:1725
 deactivate_locked_super+0xbc/0x130 fs/super.c:476
 cleanup_mnt+0x437/0x4d0 fs/namespace.c:1312
 task_work_run+0x1d9/0x270 kernel/task_work.c:233
 resume_user_mode_work include/linux/resume_user_mode.h:50 [inline]
 __exit_to_user_mode_loop kernel/entry/common.c:67 [inline]
 exit_to_user_mode_loop+0xed/0x480 kernel/entry/common.c:98
 __exit_to_user_mode_prepare include/linux/irq-entry-common.h:207 [inline]
 syscall_exit_to_user_mode_prepare include/linux/irq-entry-common.h:238 [inline]
 syscall_exit_to_user_mode include/linux/entry-common.h:328 [inline]
 do_syscall_64+0x33e/0xf80 arch/x86/entry/syscall_64.c:100
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

The buggy address belongs to the object at ffff88801b6c1800
 which belongs to the cache kmalloc-256 of size 256
The buggy address is located 8 bytes inside of
 freed 256-byte region [ffff88801b6c1800, ffff88801b6c1900)

The buggy address belongs to the physical page:
page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x1b6c0
head: order:1 mapcount:0 entire_mapcount:0 nr_pages_mapped:0 pincount:0
flags: 0x80000000000040(head|node=0|zone=1)
page_type: f5(slab)
raw: 0080000000000040 ffff88813fe00b40 dead000000000100 dead000000000122
raw: 0000000000000000 0000000800100010 00000000f5000000 0000000000000000
head: 0080000000000040 ffff88813fe00b40 dead000000000100 dead000000000122
head: 0000000000000000 0000000800100010 00000000f5000000 0000000000000000
head: 0080000000000001 ffffffffffffff81 00000000ffffffff 00000000ffffffff
head: 0000000000000000 0000000000000000 00000000ffffffff 0000000000000002
page dumped because: kasan: bad access detected
page_owner tracks the page as allocated
page last allocated via order 1, migratetype Unmovable, gfp_mask 0xd20c0(__GFP_IO|__GFP_FS|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC), pid 1, tgid 1 (swapper/0), ts 3467088608, free_ts 0
 set_page_owner include/linux/page_owner.h:32 [inline]
 post_alloc_hook+0x231/0x280 mm/page_alloc.c:1860
 prep_new_page mm/page_alloc.c:1868 [inline]
 get_page_from_freelist+0x27c8/0x2840 mm/page_alloc.c:3948
 __alloc_frozen_pages_noprof+0x18d/0x380 mm/page_alloc.c:5228
 alloc_slab_page mm/slub.c:3278 [inline]
 allocate_slab+0x77/0x660 mm/slub.c:3467
 new_slab mm/slub.c:3525 [inline]
 refill_objects+0x33c/0x3d0 mm/slub.c:7251
 refill_sheaf mm/slub.c:2816 [inline]
 __pcs_replace_empty_main+0x373/0x720 mm/slub.c:4651
 alloc_from_pcs mm/slub.c:4749 [inline]
 slab_alloc_node mm/slub.c:4883 [inline]
 __kmalloc_cache_noprof+0x44e/0x690 mm/slub.c:5410
 kmalloc_noprof include/linux/slab.h:950 [inline]
 kzalloc_noprof include/linux/slab.h:1188 [inline]
 kset_create lib/kobject.c:965 [inline]
 kset_create_and_add+0x5a/0x180 lib/kobject.c:1008
 bus_register+0x234/0x490 drivers/base/bus.c:972
 tee_init+0x42/0xc0 drivers/tee/tee_core.c:1554
 do_one_initcall+0x250/0x870 init/main.c:1392
 do_initcall_level+0x104/0x190 init/main.c:1454
 do_initcalls+0x59/0xa0 init/main.c:1470
 kernel_init_freeable+0x2a6/0x3e0 init/main.c:1703
 kernel_init+0x1d/0x1d0 init/main.c:1593
 ret_from_fork+0x514/0xb70 arch/x86/kernel/process.c:158
page_owner free stack trace missing

Memory state around the buggy address:
 ffff88801b6c1700: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
 ffff88801b6c1780: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
>ffff88801b6c1800: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                      ^
 ffff88801b6c1880: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff88801b6c1900: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
==================================================================


Tested on:

commit:         59bd5ae0 Merge tag 'for-v7.1' of git://git.kernel.org/..
git tree:       https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master
console output: https://syzkaller.appspot.com/x/log.txt?x=12611bf6580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=9055fa618d493f3
dashboard link: https://syzkaller.appspot.com/bug?extid=fa603ae6b02658401ca7
compiler:       Debian clang version 21.1.8 (++20251221033036+2078da43e25a-1~exp1~20251221153213.50), Debian LLD 21.1.8
patch:          https://syzkaller.appspot.com/x/patch.diff?x=14a124ce580000