syzbot


upstream test error: KMSAN: uninit-value in irqentry_exit_to_kernel_mode_preempt

Status: upstream: reported on 2026/04/21 21:37
Subsystems: kernel
[Documentation on labels]
Reported-by: syzbot+cdcfd55737fe43eeb3a3@syzkaller.appspotmail.com
First crash: 2d18h, last: 11h46m
Discussions (1)
Title Replies (including bot) Last reply
[syzbot] [kernel?] upstream test error: KMSAN: uninit-value in irqentry_exit_to_kernel_mode_preempt 0 (1) 2026/04/21 21:37

Sample crash report:
netdevsim netdevsim1 netdevsim1: set [1, 0] type 2 family 0 port 6081 - 0
netdevsim netdevsim1 netdevsim2: set [1, 0] type 2 family 0 port 6081 - 0
netdevsim netdevsim1 netdevsim3: set [1, 0] type 2 family 0 port 6081 - 0
=====================================================
BUG: KMSAN: uninit-value in irqentry_exit_to_kernel_mode_preempt+0xb0/0xc0 include/linux/irq-entry-common.h:472
 irqentry_exit_to_kernel_mode_preempt+0xb0/0xc0 include/linux/irq-entry-common.h:472
 irqentry_exit_to_kernel_mode include/linux/irq-entry-common.h:547 [inline]
 irqentry_exit+0x7b/0x760 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
 do_csum lib/checksum.c:68 [inline]
 ip_fast_csum+0x273/0x3f0 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:3302 [inline]
 process_scheduled_works+0xb65/0x1e40 kernel/workqueue.c:3385
 worker_thread+0xee4/0x1590 kernel/workqueue.c:3466
 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:4576 [inline]
 slab_alloc_node mm/slub.c:4898 [inline]
 __do_kmalloc_node mm/slub.c:5294 [inline]
 __kmalloc_node_track_caller_noprof+0x4f6/0x1750 mm/slub.c:5403
 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:3302 [inline]
 process_scheduled_works+0xb65/0x1e40 kernel/workqueue.c:3385
 worker_thread+0xee4/0x1590 kernel/workqueue.c:3466
 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: 1 UID: 0 PID: 13 Comm: kworker/u8:1 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/18/2026
Workqueue: events_unbound nsim_dev_trap_report_work
=====================================================

Crashes (3):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/04/23 14:07 upstream 2e6803928193 4c3406dc .config console log report [disk image] [vmlinux] [kernel image] ci-upstream-kmsan-gce-root upstream test error: KMSAN: uninit-value in irqentry_exit_to_kernel_mode_preempt
2026/04/21 17:54 upstream 4ee64205ffaa 0b6ab7ec .config console log report [disk image] [vmlinux] [kernel image] ci-upstream-kmsan-gce-root upstream test error: KMSAN: uninit-value in irqentry_exit_to_kernel_mode_preempt
2026/04/24 00:58 upstream 45dcf5e28813 9cfb3ca7 .config console log report [disk image] [vmlinux] [kernel image] ci-upstream-kmsan-gce-386-root upstream test error: KMSAN: uninit-value in irqentry_exit_to_kernel_mode_preempt
* Struck through repros no longer work on HEAD.