From nobody Fri Dec 19 05:03:52 2025 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 79CD641C72; Thu, 19 Dec 2024 01:23:07 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1734571387; cv=none; b=KWpaYBy3iLVISIhLnI513j2zhsO4xthWk4nXPmwBjRSVDdqFKkPJwbDY336imS6AXxKVfOlkd0bdjrwN4ugQzTVajSxEY56N+ZkIzcqoK8C9fTu9Px4Y1+/VaYbaCNbKC0GCe/x6WEZhHQWSkMXx9ar29mSWbaRJkDv/Sch8m/4= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1734571387; c=relaxed/simple; bh=KtKWg+kyrvySj1SXUXmmVG0S88tVlPAeJs4RX52M4Wc=; h=Message-ID:Date:From:To:Cc:Subject:References:MIME-Version: Content-Type; b=aK06bDr7KY0xHaFzkpCVI2G8Y6z7Fn2Wlyu/eG7lLLgH5/r8YWHJTZiZfAMoFoG/m0+1QZ+Nqjt+fu1nhdeSIhPq9H4pJWWpTB4aKUjXDuOaRKVLDiWIwhUsZe287Ye5WuPqTsnh7QGYaYZAZ/YZd/hx4QYwC+xpW9wi2vU+Eok= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 Received: by smtp.kernel.org (Postfix) with ESMTPSA id 04A19C4CED7; Thu, 19 Dec 2024 01:23:06 +0000 (UTC) Received: from rostedt by gandalf with local (Exim 4.98) (envelope-from ) id 1tO5GU-00000009mO6-2KG8; Wed, 18 Dec 2024 20:23:46 -0500 Message-ID: <20241219012346.411908681@goodmis.org> User-Agent: quilt/0.68 Date: Wed, 18 Dec 2024 20:23:12 -0500 From: Steven Rostedt To: linux-kernel@vger.kernel.org Cc: Masami Hiramatsu , Mark Rutland , Mathieu Desnoyers , Andrew Morton , stable@vger.kernel.org, syzbot+345e4443a21200874b18@syzkaller.appspotmail.com, Edward Adam Davis Subject: [for-linus][PATCH 1/2] ring-buffer: Fix overflow in __rb_map_vma References: <20241219012311.649442084@goodmis.org> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" From: Edward Adam Davis An overflow occurred when performing the following calculation: nr_pages =3D ((nr_subbufs + 1) << subbuf_order) - pgoff; Add a check before the calculation to avoid this problem. syzbot reported this as a slab-out-of-bounds in __rb_map_vma: BUG: KASAN: slab-out-of-bounds in __rb_map_vma+0x9ab/0xae0 kernel/trace/rin= g_buffer.c:7058 Read of size 8 at addr ffff8880767dd2b8 by task syz-executor187/5836 CPU: 0 UID: 0 PID: 5836 Comm: syz-executor187 Not tainted 6.13.0-rc2-syzkal= ler-00159-gf932fb9b4074 #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Goo= gle 11/25/2024 Call Trace: __dump_stack lib/dump_stack.c:94 [inline] dump_stack_lvl+0x116/0x1f0 lib/dump_stack.c:120 print_address_description mm/kasan/report.c:378 [inline] print_report+0xc3/0x620 mm/kasan/report.c:489 kasan_report+0xd9/0x110 mm/kasan/report.c:602 __rb_map_vma+0x9ab/0xae0 kernel/trace/ring_buffer.c:7058 ring_buffer_map+0x56e/0x9b0 kernel/trace/ring_buffer.c:7138 tracing_buffers_mmap+0xa6/0x120 kernel/trace/trace.c:8482 call_mmap include/linux/fs.h:2183 [inline] mmap_file mm/internal.h:124 [inline] __mmap_new_file_vma mm/vma.c:2291 [inline] __mmap_new_vma mm/vma.c:2355 [inline] __mmap_region+0x1786/0x2670 mm/vma.c:2456 mmap_region+0x127/0x320 mm/mmap.c:1348 do_mmap+0xc00/0xfc0 mm/mmap.c:496 vm_mmap_pgoff+0x1ba/0x360 mm/util.c:580 ksys_mmap_pgoff+0x32c/0x5c0 mm/mmap.c:542 __do_sys_mmap arch/x86/kernel/sys_x86_64.c:89 [inline] __se_sys_mmap arch/x86/kernel/sys_x86_64.c:82 [inline] __x64_sys_mmap+0x125/0x190 arch/x86/kernel/sys_x86_64.c:82 do_syscall_x64 arch/x86/entry/common.c:52 [inline] do_syscall_64+0xcd/0x250 arch/x86/entry/common.c:83 entry_SYSCALL_64_after_hwframe+0x77/0x7f The reproducer for this bug is: Reported-by: syzbot+345e4443a21200874b18@syzkaller.appspotmail.com ------------------------8<------------------------- #include #include #include #include #include int main(int argc, char **argv) { int page_size =3D getpagesize(); int fd; void *meta; system("echo 1 > /sys/kernel/tracing/buffer_size_kb"); fd =3D open("/sys/kernel/tracing/per_cpu/cpu0/trace_pipe_raw", O_RDONLY); meta =3D mmap(NULL, page_size, PROT_READ, MAP_SHARED, fd, page_size * 5); } ------------------------>8------------------------- Cc: stable@vger.kernel.org Fixes: 117c39200d9d7 ("ring-buffer: Introducing ring-buffer mapping functio= ns") Link: https://lore.kernel.org/tencent_06924B6674ED771167C23CC336C097223609@= qq.com Reported-by: syzbot+345e4443a21200874b18@syzkaller.appspotmail.com Closes: https://syzkaller.appspot.com/bug?extid=3D345e4443a21200874b18 Signed-off-by: Edward Adam Davis Signed-off-by: Steven Rostedt (Google) --- kernel/trace/ring_buffer.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-) diff --git a/kernel/trace/ring_buffer.c b/kernel/trace/ring_buffer.c index 7e257e855dd1..60210fb5b211 100644 --- a/kernel/trace/ring_buffer.c +++ b/kernel/trace/ring_buffer.c @@ -7019,7 +7019,11 @@ static int __rb_map_vma(struct ring_buffer_per_cpu *= cpu_buffer, lockdep_assert_held(&cpu_buffer->mapping_lock); =20 nr_subbufs =3D cpu_buffer->nr_pages + 1; /* + reader-subbuf */ - nr_pages =3D ((nr_subbufs + 1) << subbuf_order) - pgoff; /* + meta-page */ + nr_pages =3D ((nr_subbufs + 1) << subbuf_order); /* + meta-page */ + if (nr_pages <=3D pgoff) + return -EINVAL; + + nr_pages -=3D pgoff; =20 nr_vma_pages =3D vma_pages(vma); if (!nr_vma_pages || nr_vma_pages > nr_pages) --=20 2.45.2