[PATCH 8/8] trace-cmd record: Check the length of the protocol version received

In check_protocol_version we compare the protocol version string with
the expected one ("V3") with memcmp(). The received string could be
longer than the constant string used for the comparison. That could
lead to out of range access.

Use the known length of the fixed "V3" string for the comparison and
check that the received protocol version is not too short.

Fixes a OVERRUN error (CWE-119)

Signed-off-by: Jerome Marchand <[email protected]>
---
 tracecmd/trace-record.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/tracecmd/trace-record.c b/tracecmd/trace-record.c
index 7e84e897..6e9b4535 100644
--- a/tracecmd/trace-record.c
+++ b/tracecmd/trace-record.c
@@ -3811,7 +3811,7 @@ static void check_protocol_version(struct tracecmd_msg_handle *msg_handle)
 		msg_handle->version = V1_PROTOCOL;
 		tracecmd_plog("Use the v1 protocol\n");
 	} else {
-		if (memcmp(buf, "V3", n) != 0)
+		if (n < 3 || memcmp(buf, "V3", 3) != 0)
 			die("Cannot handle the protocol %s", buf);
 		/* OK, let's use v3 protocol */
 		write(fd, V3_MAGIC, sizeof(V3_MAGIC));
-- 
2.47.0