On Thu, Apr 17, 2014 at 06:20:37PM +0300, Ander Conselvan de Oliveira wrote:
> From: Ander Conselvan de Oliveira <[email protected]>
>
> If a message was too big to fit in the connection buffer, the code
> in wl_buffer_put would just write past the end of it.
>
> I haven't seen any real world use case that would trigger this bug, but
> it was possible to trigger it by sending a long enough string to the
> wl_data_source.offer request.
>
> https://bugs.freedesktop.org/show_bug.cgi?id=69267
Right, that looks fine. I've been debating whether we should allow
arbitrary size strings, but I think it's reasonable to cap the size.
If you're doing a protocol where a string my exceed the protocol buffer
size you should be using mmap buffers instead. The protocol was not
designed for bulk data transfer.
Kristian
> ---
> src/connection.c | 25 +++++++++++++++++--------
> tests/connection-test.c | 37 +++++++++++++++++++++++++++++++++++++
> 2 files changed, 54 insertions(+), 8 deletions(-)
>
> diff --git a/src/connection.c b/src/connection.c
> index 40a2182..63b0592 100644
> --- a/src/connection.c
> +++ b/src/connection.c
> @@ -61,11 +61,18 @@ struct wl_connection {
> int want_flush;
> };
>
> -static void
> +static int
> wl_buffer_put(struct wl_buffer *b, const void *data, size_t count)
> {
> uint32_t head, size;
>
> + if (count > sizeof(b->data)) {
> + wl_log("Data too big for buffer (%d > %d).\n",
> + count, sizeof(b->data));
> + errno = E2BIG;
> + return -1;
> + }
> +
> head = MASK(b->head);
> if (head + count <= sizeof b->data) {
> memcpy(b->data + head, data, count);
> @@ -76,6 +83,8 @@ wl_buffer_put(struct wl_buffer *b, const void *data, size_t
> count)
> }
>
> b->head += count;
> +
> + return 0;
> }
>
> static void
> @@ -243,8 +252,8 @@ decode_cmsg(struct wl_buffer *buffer, struct msghdr *msg)
> size /= sizeof(int32_t);
> for (i = 0; i < size; i++)
> close(((int*)CMSG_DATA(cmsg))[i]);
> - } else {
> - wl_buffer_put(buffer, CMSG_DATA(cmsg), size);
> + } else if (wl_buffer_put(buffer, CMSG_DATA(cmsg), size) < 0) {
> + return -1;
> }
> }
>
> @@ -350,7 +359,9 @@ wl_connection_write(struct wl_connection *connection,
> return -1;
> }
>
> - wl_buffer_put(&connection->out, data, count);
> + if (wl_buffer_put(&connection->out, data, count) < 0)
> + return -1;
> +
> connection->want_flush = 1;
>
> return 0;
> @@ -367,7 +378,7 @@ wl_connection_queue(struct wl_connection *connection,
> return -1;
> }
>
> - wl_buffer_put(&connection->out, data, count);
> + return wl_buffer_put(&connection->out, data, count);
>
> return 0;
> }
> @@ -394,9 +405,7 @@ wl_connection_put_fd(struct wl_connection *connection,
> int32_t fd)
> return -1;
> }
>
> - wl_buffer_put(&connection->fds_out, &fd, sizeof fd);
> -
> - return 0;
> + return wl_buffer_put(&connection->fds_out, &fd, sizeof fd);
> }
>
> const char *
> diff --git a/tests/connection-test.c b/tests/connection-test.c
> index 52d235d..1213875 100644
> --- a/tests/connection-test.c
> +++ b/tests/connection-test.c
> @@ -235,6 +235,27 @@ expected_fail_marshal(int expected_error, const char
> *format, ...)
> assert(errno == expected_error);
> }
>
> +static void
> +expected_fail_marshal_send(struct marshal_data *data, int expected_error,
> + const char *format, ...)
> +{
> + struct wl_closure *closure;
> + static const uint32_t opcode = 4444;
> + static struct wl_object sender = { NULL, NULL, 1234 };
> + struct wl_message message = { "test", format, NULL };
> + va_list ap;
> +
> + va_start(ap, format);
> + closure = wl_closure_vmarshal(&sender, opcode, ap, &message);
> + va_end(ap);
> +
> + assert(closure);
> + assert(wl_closure_send(closure, data->write_connection) < 0);
> + assert(errno == expected_error);
> +
> + wl_closure_destroy(closure);
> +}
> +
> TEST(connection_marshal_nullables)
> {
> struct marshal_data data;
> @@ -490,6 +511,22 @@ TEST(connection_marshal_alot)
> release_marshal_data(&data);
> }
>
> +TEST(connection_marshal_too_big)
> +{
> + struct marshal_data data;
> + char *big_string = malloc(5000);
> +
> + memset(big_string, ' ', 4999);
> + big_string[4999] = '\0';
> +
> + setup_marshal_data(&data);
> +
> + expected_fail_marshal_send(&data, E2BIG, "s", big_string);
> +
> + release_marshal_data(&data);
> + free(big_string);
> +}
> +
> static void
> marshal_helper(const char *format, void *handler, ...)
> {
> --
> 1.8.3.2
>
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