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Mon, 21 Apr 2025 06:49:45 -0700 (PDT) Received: from localhost.localdomain ([121.185.186.233]) by smtp.gmail.com with ESMTPSA id d9443c01a7336-22c50bdae5dsm65563115ad.35.2025.04.21.06.49.44 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 21 Apr 2025 06:49:45 -0700 (PDT) From: Jeongjun Park To: rostedt@goodmis.org, mhiramat@kernel.org Cc: linux-kernel@vger.kernel.org, linux-trace-kernel@vger.kernel.org, syzbot+c8cd2d2c412b868263fb@syzkaller.appspotmail.com, Jeongjun Park Subject: [PATCH] tracing: fix oob write in trace_seq_to_buffer() Date: Mon, 21 Apr 2025 22:49:36 +0900 Message-ID: <20250421134936.89104-1-aha310510@gmail.com> X-Mailer: git-send-email 2.43.0 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" syzbot reported this bug: =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D BUG: KASAN: slab-out-of-bounds in trace_seq_to_buffer kernel/trace/trace.c:= 1830 [inline] BUG: KASAN: slab-out-of-bounds in tracing_splice_read_pipe+0x6be/0xdd0 kern= el/trace/trace.c:6822 Write of size 4507 at addr ffff888032b6b000 by task syz.2.320/7260 CPU: 1 UID: 0 PID: 7260 Comm: syz.2.320 Not tainted 6.15.0-rc1-syzkaller-00= 301-g3bde70a2c827 #0 PREEMPT(full)=20 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Goo= gle 02/12/2025 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:408 [inline] print_report+0xc3/0x670 mm/kasan/report.c:521 kasan_report+0xe0/0x110 mm/kasan/report.c:634 check_region_inline mm/kasan/generic.c:183 [inline] kasan_check_range+0xef/0x1a0 mm/kasan/generic.c:189 __asan_memcpy+0x3c/0x60 mm/kasan/shadow.c:106 trace_seq_to_buffer kernel/trace/trace.c:1830 [inline] tracing_splice_read_pipe+0x6be/0xdd0 kernel/trace/trace.c:6822 .... =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D It has been reported that trace_seq_to_buffer() attempts to copy more than PAGE_SIZE data into buf, so we need to add code to check the size of the=20 cnt value to prevent this. Reported-by: syzbot+c8cd2d2c412b868263fb@syzkaller.appspotmail.com Fixes: 3c56819b14b0 ("tracing: splice support for tracing_pipe") Signed-off-by: Jeongjun Park --- kernel/trace/trace.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c index 8ddf6b17215c..8ba6ea38411d 100644 --- a/kernel/trace/trace.c +++ b/kernel/trace/trace.c @@ -1827,6 +1827,8 @@ static ssize_t trace_seq_to_buffer(struct trace_seq *= s, void *buf, size_t cnt) len =3D trace_seq_used(s) - s->readpos; if (cnt > len) cnt =3D len; + if (cnt > PAGE_SIZE) + return -EINVAL; memcpy(buf, s->buffer + s->readpos, cnt); =20 s->readpos +=3D cnt; --