Re: [syzbot] [jfs?] KMSAN: uninit-value in BT_STACK_DUMP

syzbot
2025-05-06T15:38:03Z

Hello,

syzbot has tested the proposed patch but the reproducer is still triggering an issue:
KMSAN: use-after-free in dtSearch

loop0: detected capacity change from 0 to 32768
=====================================================
BUG: KMSAN: use-after-free in UniStrncmp_le fs/jfs/jfs_unicode.h:55 [inline]
BUG: KMSAN: use-after-free in dtCompare fs/jfs/jfs_dtree.c:3340 [inline]
BUG: KMSAN: use-after-free in dtSearch+0x1261/0x3d30 fs/jfs/jfs_dtree.c:650
UniStrncmp_le fs/jfs/jfs_unicode.h:55 [inline]
dtCompare fs/jfs/jfs_dtree.c:3340 [inline]
dtSearch+0x1261/0x3d30 fs/jfs/jfs_dtree.c:650
jfs_lookup+0x18b/0x5a0 fs/jfs/namei.c:1461
lookup_one_qstr_excl_raw+0x204/0x5b0 fs/namei.c:1689
lookup_one_qstr_excl fs/namei.c:1711 [inline]
do_unlinkat+0x2e3/0xe50 fs/namei.c:4631
__do_sys_unlink fs/namei.c:4689 [inline]
__se_sys_unlink fs/namei.c:4687 [inline]
__x64_sys_unlink+0x71/0xb0 fs/namei.c:4687
x64_sys_call+0x29de/0x3db0 arch/x86/include/generated/asm/syscalls_64.h:88
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0xd9/0x1b0 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f

Uninit was created at:
slab_free_hook mm/slub.c:2324 [inline]
slab_free mm/slub.c:4656 [inline]
kmem_cache_free+0x286/0xf00 mm/slub.c:4758
__d_free+0x43/0x60 fs/dcache.c:336
rcu_do_batch kernel/rcu/tree.c:2568 [inline]
rcu_core+0xa5a/0x21e0 kernel/rcu/tree.c:2824
rcu_core_si+0x12/0x20 kernel/rcu/tree.c:2841
handle_softirqs+0x166/0x6e0 kernel/softirq.c:579
__do_softirq kernel/softirq.c:613 [inline]
invoke_softirq kernel/softirq.c:453 [inline]
__irq_exit_rcu+0x66/0x180 kernel/softirq.c:680
irq_exit_rcu+0x12/0x20 kernel/softirq.c:696
instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1049 [inline]
sysvec_apic_timer_interrupt+0x84/0x90 arch/x86/kernel/apic/apic.c:1049
asm_sysvec_apic_timer_interrupt+0x1f/0x30 arch/x86/include/asm/idtentry.h:702

CPU: 0 UID: 0 PID: 6979 Comm: syz.0.35 Not tainted 6.15.0-rc3-syzkaller-00094-g02ddfb981de8-dirty #0 PREEMPT(undef)
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/29/2025
=====================================================

Tested on:

commit: 02ddfb98 Merge tag 'scsi-fixes' of git://git.kernel.or..
git tree: git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
console output: https://syzkaller.appspot.com/x/log.txt?x=134ee8f4580000
kernel config: https://syzkaller.appspot.com/x/.config?x=9dc42c34a3f5c357
dashboard link: https://syzkaller.appspot.com/bug?extid=ba5f49027aace342d24d
compiler: Debian clang version 20.1.2 (++20250402124445+58df0ef89dd6-1~exp1~20250402004600.97), Debian LLD 20.1.2
patch: https://syzkaller.appspot.com/x/patch.diff?x=10efba70580000