tpm_i2c_infineon: fix potential buffer overruns caused by bit glitches on the bus
authorJeremy Boone <jeremy.boone@nccgroup.trust>
Thu, 8 Feb 2018 20:30:01 +0000 (12:30 -0800)
committerJames Morris <james.morris@microsoft.com>
Mon, 26 Feb 2018 23:43:44 +0000 (15:43 -0800)
Discrete TPMs are often connected over slow serial buses which, on
some platforms, can have glitches causing bit flips.  In all the
driver _recv() functions, we need to use a u32 to unmarshal the
response size, otherwise a bit flip of the 31st bit would cause the
expected variable to go negative, which would then try to read a huge
amount of data.  Also sanity check that the expected amount of data is
large enough for the TPM header.

Signed-off-by: Jeremy Boone <jeremy.boone@nccgroup.trust>
Cc: stable@vger.kernel.org
Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com>
Reviewed-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
Signed-off-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
Signed-off-by: James Morris <james.morris@microsoft.com>
drivers/char/tpm/tpm_i2c_infineon.c

index c1dd39eaaeebb1f474d2d9f8b0d1e98e3559f27f..6116cd05e2287999c69ea4c5432098f159a44379 100644 (file)
@@ -473,7 +473,8 @@ static int recv_data(struct tpm_chip *chip, u8 *buf, size_t count)
 static int tpm_tis_i2c_recv(struct tpm_chip *chip, u8 *buf, size_t count)
 {
        int size = 0;
 static int tpm_tis_i2c_recv(struct tpm_chip *chip, u8 *buf, size_t count)
 {
        int size = 0;
-       int expected, status;
+       int status;
+       u32 expected;
 
        if (count < TPM_HEADER_SIZE) {
                size = -EIO;
 
        if (count < TPM_HEADER_SIZE) {
                size = -EIO;
@@ -488,7 +489,7 @@ static int tpm_tis_i2c_recv(struct tpm_chip *chip, u8 *buf, size_t count)
        }
 
        expected = be32_to_cpu(*(__be32 *)(buf + 2));
        }
 
        expected = be32_to_cpu(*(__be32 *)(buf + 2));
-       if ((size_t) expected > count) {
+       if (((size_t) expected > count) || (expected < TPM_HEADER_SIZE)) {
                size = -EIO;
                goto out;
        }
                size = -EIO;
                goto out;
        }