mmc: sdio: Check for CISTPL_VERS_1 buffer size

Before parsing CISTPL_VERS_1 structure check that its size is at least two
bytes to prevent buffer overflow.

Signed-off-by: Pali Rohár <pali@kernel.org>
Link: https://lore.kernel.org/r/20200727133837.19086-2-pali@kernel.org
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>

diff --git a/drivers/mmc/core/sdio_cis.c b/drivers/mmc/core/sdio_cis.c
index e065527..3efaa95 100644 (file)
--- a/drivers/mmc/core/sdio_cis.c
+++ b/drivers/mmc/core/sdio_cis.c
@@ -26,6 +26,9 @@ static int cistpl_vers_1(struct mmc_card *card, struct sdio_func *func,
        unsigned i, nr_strings;
        char **buffer, *string;
 
+       if (size < 2)
+               return 0;
+
        /* Find all null-terminated (including zero length) strings in
           the TPLLV1_INFO field. Trailing garbage is ignored. */
        buf += 2;