The incoming message size from the device header (header.size) is trusted without checking that it is at least the size of the message header itself, but a value smaller than sizeof(struct gb_operation_msg_hdr) underflows request_size in gb_operation_create_incoming(), wraps around in gb_operation_message_alloc(), and results in a tiny buffer that is then written past its end in gb_operation_message_init().
Reject undersized messages before parsing the message header.
Fixes: d37b1db13f8b ("greybus: refactor gb_connection_recv()") Reported-by: syzbot+2fd6aefc361af86911d5@syzkaller.appspotmail.com Link: https://syzkaller.appspot.com/bug?extid=2fd6aefc361af86911d5 Cc: stable@vger.kernel.org Signed-off-by: Adriano Cordova adrianox@gmail.com --- drivers/greybus/operation.c | 8 ++++++++ 1 file changed, 8 insertions(+)
diff --git a/drivers/greybus/operation.c b/drivers/greybus/operation.c index 7e12ffb2dd..df6daee4fb 100644 --- a/drivers/greybus/operation.c +++ b/drivers/greybus/operation.c @@ -1047,6 +1047,14 @@ void gb_connection_recv(struct gb_connection *connection, /* Use memcpy as data may be unaligned */ memcpy(&header, data, sizeof(header)); msg_size = le16_to_cpu(header.size); + if (msg_size < sizeof(header)) { + dev_err_ratelimited(dev, + "%s: malformed message 0x%04x of type 0x%02x received (%zu < %zu)\n", + connection->name, + le16_to_cpu(header.operation_id), + header.type, msg_size, sizeof(header)); + return; + } if (size < msg_size) { dev_err_ratelimited(dev, "%s: incomplete message 0x%04x of type 0x%02x received (%zu < %zu)\n",