From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-oi1-f205.google.com (mail-oi1-f205.google.com [209.85.167.205]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id E5B9A30DEB2 for ; Fri, 21 Aug 2026 13:17:43 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.167.205 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1787318267; cv=none; b=PWiZ1sKti5NztaDnAGAosFNpz8+BxAp+ZEfzoKsZF//BGKdqwmGm+bPRAVggk1DI48zSVZ+LbSiInpLZ2ywayCc0KMddUw4rg9iXyr3uiHs61cylSNBYIiRsfFk8gFxCxbVbgRolCjuO3882bZS0juNH+H7tvkHhY6dpyDe6IpU= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1787318267; c=relaxed/simple; bh=Coa+AggbCFxMPrhay90dyvE8KIF8DPbctIHdy2dJGKU=; h=MIME-Version:Date:In-Reply-To:Message-ID:Subject:From:To: Content-Type; 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2002:a05:6820:150b:b0:6a1:3e91:dcac with SMTP id 006d021491bc7-6b159433d65mr6777750eaf.31.1787318258485; Fri, 21 Aug 2026 06:17:38 -0700 (PDT) Date: Fri, 21 Aug 2026 06:17:38 -0700 In-Reply-To: <6a853da3.ae6ddae5.3da009.0006.GAE@google.com> X-Google-Appengine-App-Id: s~syzkaller X-Google-Appengine-App-Id-Alias: syzkaller Message-ID: <6a884ff2.ae6ddae5.3da009.0037.GAE@google.com> Subject: Re: [syzbot] [net?] [nfc?] KASAN: slab-out-of-bounds Read in __dynamic_pr_debug From: syzbot 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 Content-Type: text/plain; charset="UTF-8" syzbot has found a reproducer for 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=17d30179580000 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 syz repro: https://syzkaller.appspot.com/x/repro.syz?x=13d43e79580000 C reproducer: https://syzkaller.appspot.com/x/repro.c?x=1746fa25580000 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 ================================================================== BUG: KASAN: slab-out-of-bounds in string_nocheck+0xd8/0x140 lib/vsprintf.c:648 Read of size 1 at addr ffff0000d0cf899c by task syz.0.17/4947 CPU: 1 UID: 0 PID: 4947 Comm: syz.0.17 Not tainted syzkaller #0 PREEMPT 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 4947: 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 ffff0000d0cf8980 which belongs to the cache kmalloc-32 of size 32 The buggy address is located 0 bytes to the right of allocated 28-byte region [ffff0000d0cf8980, ffff0000d0cf899c) The buggy address belongs to the physical page: page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x110cf8 flags: 0x5ffc00000000000(node=0|zone=2|lastcpupid=0x7ff) page_type: f5(slab) raw: 05ffc00000000000 ffff0000c0001780 dead000000000100 dead000000000122 raw: 0000000000000000 0000000800400040 00000000f5000000 0000000000000000 page dumped because: kasan: bad access detected Memory state around the buggy address: ffff0000d0cf8880: fa fb fb fb fc fc fc fc fa fb fb fb fc fc fc fc ffff0000d0cf8900: fa fb fb fb fc fc fc fc fa fb fb fb fc fc fc fc >ffff0000d0cf8980: 00 00 00 04 fc fc fc fc 00 00 00 fc fc fc fc fc ^ ffff0000d0cf8a00: 00 00 00 00 fc fc fc fc 00 00 00 00 fc fc fc fc ffff0000d0cf8a80: fa fb fb fb fc fc fc fc 00 00 00 fc fc fc fc fc ================================================================== --- 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.