Re: [syzbot] [hfs?] KMSAN: uninit-value in hfsplus_bnode_find

syzbot
2026-04-15T04:10:02Z

Hello,

syzbot has tested the proposed patch but the reproducer is still triggering an issue:
KMSAN: uninit-value in irqentry_exit_to_kernel_mode_preempt

=====================================================
BUG: KMSAN: uninit-value in irqentry_exit_to_kernel_mode_preempt+0xe3/0x120 include/linux/irq-entry-common.h:472
irqentry_exit_to_kernel_mode_preempt+0xe3/0x120 include/linux/irq-entry-common.h:472
irqentry_exit_to_kernel_mode include/linux/irq-entry-common.h:547 [inline]
irqentry_exit+0x77/0x710 kernel/entry/common.c:164
sysvec_apic_timer_interrupt+0x52/0x90 arch/x86/kernel/apic/apic.c:1061
asm_sysvec_apic_timer_interrupt+0x1f/0x30 arch/x86/include/asm/idtentry.h:697
smap_save mm/kmsan/instrumentation.c:93 [inline]
get_shadow_origin_ptr mm/kmsan/instrumentation.c:35 [inline]
__msan_metadata_ptr_for_load_4+0x11/0x40 mm/kmsan/instrumentation.c:93
do_csum lib/checksum.c:64 [inline]
ip_fast_csum+0x1e6/0x3f0 lib/checksum.c:99
nsim_dev_trap_skb_build drivers/net/netdevsim/dev.c:842 [inline]
nsim_dev_trap_report drivers/net/netdevsim/dev.c:876 [inline]
nsim_dev_trap_report_work+0x8c0/0x1430 drivers/net/netdevsim/dev.c:922
process_one_work kernel/workqueue.c:3288 [inline]
process_scheduled_works+0xb65/0x1e40 kernel/workqueue.c:3371
worker_thread+0xee4/0x1590 kernel/workqueue.c:3452
kthread+0x53f/0x600 kernel/kthread.c:436
ret_from_fork+0x20f/0x8d0 arch/x86/kernel/process.c:158
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245

Uninit was created at:
slab_post_alloc_hook mm/slub.c:4545 [inline]
slab_alloc_node mm/slub.c:4866 [inline]
__do_kmalloc_node mm/slub.c:5259 [inline]
__kmalloc_node_track_caller_noprof+0x4f6/0x1750 mm/slub.c:5368
kmalloc_reserve net/core/skbuff.c:635 [inline]
__alloc_skb+0x90d/0x1190 net/core/skbuff.c:713
alloc_skb include/linux/skbuff.h:1383 [inline]
nsim_dev_trap_skb_build drivers/net/netdevsim/dev.c:819 [inline]
nsim_dev_trap_report drivers/net/netdevsim/dev.c:876 [inline]
nsim_dev_trap_report_work+0x3f2/0x1430 drivers/net/netdevsim/dev.c:922
process_one_work kernel/workqueue.c:3288 [inline]
process_scheduled_works+0xb65/0x1e40 kernel/workqueue.c:3371
worker_thread+0xee4/0x1590 kernel/workqueue.c:3452
kthread+0x53f/0x600 kernel/kthread.c:436
ret_from_fork+0x20f/0x8d0 arch/x86/kernel/process.c:158
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245

CPU: 0 UID: 0 PID: 134 Comm: kworker/u8:6 Not tainted syzkaller #0 PREEMPT(full)
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/18/2026
Workqueue: events_unbound nsim_dev_trap_report_work
=====================================================

Tested on:

commit: 91a4855d Merge tag 'net-next-7.1' of git://git.kernel...
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=14f418ce580000
kernel config: https://syzkaller.appspot.com/x/.config?x=9f67daa5723e634c
dashboard link: https://syzkaller.appspot.com/bug?extid=217eb327242d08197efb
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=170efb02580000