[syzbot] [kernel?] KASAN: vmalloc-out-of-bounds Read in run_irq_workd

[syzbot] [kernel?] KASAN: vmalloc-out-of-bounds Read in run_irq_workd

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit:    fab1beda7597 Merge tag 'devicetree-fixes-for-6.17-1' of gi..
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=1690def0580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=e1e1566c7726877e
dashboard link: https://syzkaller.appspot.com/bug?extid=2617fc732430968b45d2
compiler:       Debian clang version 20.1.7 (++20250616065708+6146a88f6049-1~exp1~20250616065826.132), Debian LLD 20.1.7
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=115f7c62580000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/5da7c25b1d17/disk-fab1beda.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/1da8f2d76781/vmlinux-fab1beda.xz
kernel image: https://storage.googleapis.com/syzbot-assets/edda5f26e059/bzImage-fab1beda.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+2617fc732430968b45d2@syzkaller.appspotmail.com

==================================================================
BUG: KASAN: vmalloc-out-of-bounds in irq_work_run_list kernel/irq_work.c:251 [inline]
BUG: KASAN: vmalloc-out-of-bounds in run_irq_workd+0x116/0x190 kernel/irq_work.c:305
Read of size 8 at addr ffffc90005289090 by task irq_work/1/26

CPU: 1 UID: 0 PID: 26 Comm: irq_work/1 Not tainted syzkaller #0 PREEMPT_{RT,(full)} 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/12/2025
Call Trace:
 <TASK>
 dump_stack_lvl+0x189/0x250 lib/dump_stack.c:120
 print_address_description mm/kasan/report.c:378 [inline]
 print_report+0xca/0x240 mm/kasan/report.c:482
 kasan_report+0x118/0x150 mm/kasan/report.c:595
 irq_work_run_list kernel/irq_work.c:251 [inline]
 run_irq_workd+0x116/0x190 kernel/irq_work.c:305
 smpboot_thread_fn+0x542/0xa60 kernel/smpboot.c:160
 kthread+0x711/0x8a0 kernel/kthread.c:463
 ret_from_fork+0x3fc/0x770 arch/x86/kernel/process.c:148
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
 </TASK>

The buggy address belongs to a vmalloc virtual mapping
Memory state around the buggy address:
 ffffc90005288f80: f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8
 ffffc90005289000: f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8
>ffffc90005289080: f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8
                         ^
 ffffc90005289100: f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8
 ffffc90005289180: f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8
==================================================================


---
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Re: [syzbot] [kernel?] KASAN: vmalloc-out-of-bounds Read in run_irq_workd

[syzbot]

syzbot has found a reproducer for the following issue on:

HEAD commit:    ec714e371f22 Merge tag 'perf-tools-for-v6.18-1-2025-10-08'..
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=1284a1e2580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=db9c80a8900dca57
dashboard link: https://syzkaller.appspot.com/bug?extid=2617fc732430968b45d2
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=1200b458580000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=17a24b34580000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/6d5cce2bcf5d/disk-ec714e37.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/60dff1e3a58f/vmlinux-ec714e37.xz
kernel image: https://storage.googleapis.com/syzbot-assets/6a1823720b55/bzImage-ec714e37.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+2617fc732430968b45d2@syzkaller.appspotmail.com

==================================================================
BUG: KASAN: vmalloc-out-of-bounds in irq_work_run_list kernel/irq_work.c:251 [inline]
BUG: KASAN: vmalloc-out-of-bounds in run_irq_workd+0x116/0x190 kernel/irq_work.c:305
Read of size 8 at addr ffffc9000cc08090 by task irq_work/1/26

CPU: 1 UID: 0 PID: 26 Comm: irq_work/1 Not tainted syzkaller #0 PREEMPT_{RT,(full)} 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/02/2025
Call Trace:
 <TASK>
 dump_stack_lvl+0x189/0x250 lib/dump_stack.c:120
 print_address_description mm/kasan/report.c:378 [inline]
 print_report+0xca/0x240 mm/kasan/report.c:482
 kasan_report+0x118/0x150 mm/kasan/report.c:595
 irq_work_run_list kernel/irq_work.c:251 [inline]
 run_irq_workd+0x116/0x190 kernel/irq_work.c:305
 smpboot_thread_fn+0x53f/0xa60 kernel/smpboot.c:160
 kthread+0x711/0x8a0 kernel/kthread.c:463
 ret_from_fork+0x4b9/0x870 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
 </TASK>

The buggy address belongs to a vmalloc virtual mapping
Memory state around the buggy address:
 ffffc9000cc07f80: f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8
 ffffc9000cc08000: f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8
>ffffc9000cc08080: f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8
                         ^
 ffffc9000cc08100: f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8
 ffffc9000cc08180: f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8
==================================================================


---
If you want syzbot to run the reproducer, reply with:
#syz test: git://repo/address.git branch-or-commit-hash
If you attach or paste a git patch, syzbot will apply it before testing.

[PATCH] bpf: sync pending IRQ work before freeing ring buffer

[neqbal]

#syz test

Fix a possible vmalloc out-of-bounds access caused by pending IRQ work

Reported-by: syzbot+2617fc732430968b45d2@syzkaller.appspotmail.com
Signed-off-by: neqbal <nooraineqbal@gmail.com>
---
 kernel/bpf/ringbuf.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/kernel/bpf/ringbuf.c b/kernel/bpf/ringbuf.c
index 719d73299397..a6597417412f 100644
--- a/kernel/bpf/ringbuf.c
+++ b/kernel/bpf/ringbuf.c
@@ -216,6 +216,12 @@ static struct bpf_map *ringbuf_map_alloc(union bpf_attr *attr)
 
 static void bpf_ringbuf_free(struct bpf_ringbuf *rb)
 {
+	/* Ensure all pending IRQ work completes before freeing.
+	 * In PREEMPT_RT, IRQ work runs in thread context and can
+	 * race with ring buffer destruction.
+	 */
+	irq_work_sync(&rb->work);
+
 	/* copy pages pointer and nr_pages to local variable, as we are going
 	 * to unmap rb itself with vunmap() below
 	 */
-- 
2.51.0

Re: [syzbot] [kernel?] KASAN: vmalloc-out-of-bounds Read in run_irq_workd

[syzbot]

Hello,

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

Reported-by: syzbot+2617fc732430968b45d2@syzkaller.appspotmail.com
Tested-by: syzbot+2617fc732430968b45d2@syzkaller.appspotmail.com

Tested on:

commit:         6f3b6e91 Merge tag 'io_uring-6.18-20251016' of git://g..
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=1217cb04580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=af9170887d81dea1
dashboard link: https://syzkaller.appspot.com/bug?extid=2617fc732430968b45d2
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=12e5ede2580000

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