From: Masami Hiramatsu (Google) Date: Mon, 16 Feb 2026 09:30:15 +0000 (+0900) Subject: tracing: ring-buffer: Fix to check event length before using X-Git-Tag: v7.0-rc1~32^2~3 X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=912b0ee248c529a4f45d1e7f568dc1adddbf2a4a;p=thirdparty%2Fkernel%2Flinux.git tracing: ring-buffer: Fix to check event length before using Check the event length before adding it for accessing next index in rb_read_data_buffer(). Since this function is used for validating possibly broken ring buffers, the length of the event could be broken. In that case, the new event (e + len) can point a wrong address. To avoid invalid memory access at boot, check whether the length of each event is in the possible range before using it. Cc: stable@vger.kernel.org Cc: Mathieu Desnoyers Fixes: 5f3b6e839f3c ("ring-buffer: Validate boot range memory events") Link: https://patch.msgid.link/177123421541.142205.9414352170164678966.stgit@devnote2 Signed-off-by: Masami Hiramatsu (Google) Signed-off-by: Steven Rostedt (Google) --- diff --git a/kernel/trace/ring_buffer.c b/kernel/trace/ring_buffer.c index bdc8010d8f48..1e7a34a31851 100644 --- a/kernel/trace/ring_buffer.c +++ b/kernel/trace/ring_buffer.c @@ -1849,6 +1849,7 @@ static int rb_read_data_buffer(struct buffer_data_page *dpage, int tail, int cpu struct ring_buffer_event *event; u64 ts, delta; int events = 0; + int len; int e; *delta_ptr = 0; @@ -1856,9 +1857,12 @@ static int rb_read_data_buffer(struct buffer_data_page *dpage, int tail, int cpu ts = dpage->time_stamp; - for (e = 0; e < tail; e += rb_event_length(event)) { + for (e = 0; e < tail; e += len) { event = (struct ring_buffer_event *)(dpage->data + e); + len = rb_event_length(event); + if (len <= 0 || len > tail - e) + return -1; switch (event->type_len) {