From: syzbot <syzbot+1e3df0852e82c21ca418@syzkaller.appspotmail.com>
To: davem@davemloft.net, david@ixit.cz, edumazet@google.com,
horms@kernel.org, krzk@kernel.org, kuba@kernel.org,
linux-kernel@vger.kernel.org, netdev@vger.kernel.org,
oe-linux-nfc@lists.linux.dev, pabeni@redhat.com,
syzkaller-bugs@googlegroups.com
Subject: [syzbot] [net?] [nfc?] KASAN: slab-out-of-bounds Read in __dynamic_pr_debug
Date: Tue, 18 Aug 2026 22:22:43 -0700 [thread overview]
Message-ID: <6a853da3.ae6ddae5.3da009.0006.GAE@google.com> (raw)
Hello,
syzbot found the following issue on:
HEAD commit: 21d6ac051080 Merge branch 'for-next/core' into for-kernelci
git tree: git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git for-kernelci
console output: https://syzkaller.appspot.com/x/log.txt?x=13653679580000
kernel config: https://syzkaller.appspot.com/x/.config?x=d1128bc53f2ef7f3
dashboard link: https://syzkaller.appspot.com/bug?extid=1e3df0852e82c21ca418
compiler: Debian clang version 22.1.8 (++20260613092233+e80beda6e255-1~exp1~20260613092250.77), Debian LLD 22.1.8
userspace arch: arm64
Unfortunately, I don't have any reproducer for this issue yet.
Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/88380e2ddcb9/disk-21d6ac05.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/5dba5c2896b7/vmlinux-21d6ac05.xz
kernel image: https://storage.googleapis.com/syzbot-assets/52ac739e37e0/Image-21d6ac05.gz.xz
IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+1e3df0852e82c21ca418@syzkaller.appspotmail.com
dvmrp0: entered allmulticast mode
==================================================================
BUG: KASAN: slab-out-of-bounds in string_nocheck+0xd8/0x140 lib/vsprintf.c:648
Read of size 1 at addr ffff0000c2554ae1 by task syz.2.798/8384
CPU: 1 UID: 0 PID: 8384 Comm: syz.2.798 Tainted: G L syzkaller #0 PREEMPT
Tainted: [L]=SOFTLOCKUP
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/07/2026
Call trace:
show_stack+0x2c/0x3c arch/arm64/kernel/stacktrace.c:499 (C)
__dump_stack+0x30/0x40 lib/dump_stack.c:94
dump_stack_lvl+0xd8/0x12c lib/dump_stack.c:120
print_address_description+0xb0/0x238 mm/kasan/report.c:378
print_report+0x68/0x84 mm/kasan/report.c:482
kasan_report+0x8c/0xc4 mm/kasan/report.c:595
__asan_report_load1_noabort+0x20/0x2c mm/kasan/report_generic.c:378
string_nocheck+0xd8/0x140 lib/vsprintf.c:648
string+0x8c/0xc8 lib/vsprintf.c:730
vsnprintf+0x880/0xd10 lib/vsprintf.c:2945
va_format lib/vsprintf.c:1725 [inline]
pointer+0x5e8/0x6b4 lib/vsprintf.c:2573
vsnprintf+0x618/0xd10 lib/vsprintf.c:2949
vprintk_store+0x344/0xb94 kernel/printk/printk.c:2307
vprintk_emit+0x1bc/0x514 kernel/printk/printk.c:2455
vprintk_default+0x54/0x80 kernel/printk/printk.c:2494
vprintk+0x9c/0x114 kernel/printk/printk_safe.c:82
_printk+0xe0/0x130 kernel/printk/printk.c:2504
__dynamic_pr_debug+0x148/0x1e4 lib/dynamic_debug.c:879
nfc_llcp_wks_sap net/nfc/llcp_core.c:344 [inline]
nfc_llcp_get_sdp_ssap+0x350/0x3fc net/nfc/llcp_core.c:420
llcp_sock_bind+0x2e0/0x58c net/nfc/llcp_sock.c:114
__sys_bind_socket net/socket.c:1920 [inline]
__sys_bind+0x1c4/0x268 net/socket.c:1951
__do_sys_bind net/socket.c:1956 [inline]
__se_sys_bind net/socket.c:1954 [inline]
__arm64_sys_bind+0x84/0x9c net/socket.c:1954
__invoke_syscall arch/arm64/kernel/syscall.c:35 [inline]
invoke_syscall+0x98/0x244 arch/arm64/kernel/syscall.c:49
el0_svc_common+0xec/0x23c arch/arm64/kernel/syscall.c:121
do_el0_svc+0x4c/0x5c arch/arm64/kernel/syscall.c:140
el0_svc+0x64/0x260 arch/arm64/kernel/entry-common.c:758
el0t_64_sync_handler+0x44/0x104 arch/arm64/kernel/entry-common.c:777
el0t_64_sync+0x198/0x19c arch/arm64/kernel/entry.S:590
Allocated by task 8384:
kasan_save_stack mm/kasan/common.c:57 [inline]
kasan_save_track+0x40/0x78 mm/kasan/common.c:78
kasan_save_alloc_info+0x40/0x50 mm/kasan/generic.c:570
poison_kmalloc_redzone mm/kasan/common.c:398 [inline]
__kasan_kmalloc+0x9c/0xb4 mm/kasan/common.c:415
kasan_kmalloc include/linux/kasan.h:263 [inline]
__do_kmalloc_node mm/slub.c:5334 [inline]
__kmalloc_node_track_caller_noprof+0x434/0x6d4 mm/slub.c:5471
kmemdup_noprof+0x44/0x8c mm/util.c:138
kmemdup_noprof include/linux/fortify-string.h:715 [inline]
llcp_sock_bind+0x2b0/0x58c net/nfc/llcp_sock.c:107
__sys_bind_socket net/socket.c:1920 [inline]
__sys_bind+0x1c4/0x268 net/socket.c:1951
__do_sys_bind net/socket.c:1956 [inline]
__se_sys_bind net/socket.c:1954 [inline]
__arm64_sys_bind+0x84/0x9c net/socket.c:1954
__invoke_syscall arch/arm64/kernel/syscall.c:35 [inline]
invoke_syscall+0x98/0x244 arch/arm64/kernel/syscall.c:49
el0_svc_common+0xec/0x23c arch/arm64/kernel/syscall.c:121
do_el0_svc+0x4c/0x5c arch/arm64/kernel/syscall.c:140
el0_svc+0x64/0x260 arch/arm64/kernel/entry-common.c:758
el0t_64_sync_handler+0x44/0x104 arch/arm64/kernel/entry-common.c:777
el0t_64_sync+0x198/0x19c arch/arm64/kernel/entry.S:590
The buggy address belongs to the object at ffff0000c2554ae0
which belongs to the cache kmalloc-8 of size 8
The buggy address is located 0 bytes to the right of
allocated 1-byte region [ffff0000c2554ae0, ffff0000c2554ae1)
The buggy address belongs to the physical page:
page: refcount:0 mapcount:0 mapping:0000000000000000 index:0xffff0000c2554a80 pfn:0x102554
flags: 0x5ffc00000000200(workingset|node=0|zone=2|lastcpupid=0x7ff)
page_type: f5(slab)
raw: 05ffc00000000200 ffff0000c0001500 fffffdffc318aa10 fffffdffc30937d0
raw: ffff0000c2554a80 0000000800800069 00000000f5000000 0000000000000000
page dumped because: kasan: bad access detected
Memory state around the buggy address:
ffff0000c2554980: 00 fc fc fc 07 fc fc fc fa fc fc fc 07 fc fc fc
ffff0000c2554a00: fa fc fc fc fa fc fc fc fa fc fc fc 07 fc fc fc
>ffff0000c2554a80: fa fc fc fc 05 fc fc fc 05 fc fc fc 01 fc fc fc
^
ffff0000c2554b00: fa fc fc fc 05 fc fc fc 00 fc fc fc 00 fc fc fc
ffff0000c2554b80: 00 fc fc fc 00 fc fc fc fa fc fc fc 00 fc fc fc
==================================================================
---
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reply other threads:[~2026-08-19 5:22 UTC|newest]
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