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authorJeremy Boone <jeremy.boone@nccgroup.trust>2018-02-08 12:32:06 -0800
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2018-03-11 16:21:27 +0100
commit922f22e680e2ed1277b53f8e183265b71b5dfcf3 (patch)
treeeceb82e3b7ed5dcc5cb34b1a6efbc62ed92a423e /drivers/char
parent15dcd3aa1542a1f00df25dd741200c720b870793 (diff)
tpm_tis: fix potential buffer overruns caused by bit glitches on the bus
commit 6bb320ca4a4a7b5b3db8c8d7250cc40002046878 upstream. 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> Tested-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.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> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'drivers/char')
-rw-r--r--drivers/char/tpm/tpm_tis_core.c5
1 files changed, 3 insertions, 2 deletions
diff --git a/drivers/char/tpm/tpm_tis_core.c b/drivers/char/tpm/tpm_tis_core.c
index 4d24ec3d7cd6..caf7b18895f2 100644
--- a/drivers/char/tpm/tpm_tis_core.c
+++ b/drivers/char/tpm/tpm_tis_core.c
@@ -208,7 +208,8 @@ static int tpm_tis_recv(struct tpm_chip *chip, u8 *buf, size_t count)
{
struct tpm_tis_data *priv = dev_get_drvdata(&chip->dev);
int size = 0;
- int expected, status;
+ int status;
+ u32 expected;
if (count < TPM_HEADER_SIZE) {
size = -EIO;
@@ -223,7 +224,7 @@ static int tpm_tis_recv(struct tpm_chip *chip, u8 *buf, size_t count)
}
expected = be32_to_cpu(*(__be32 *) (buf + 2));
- if (expected > count) {
+ if (expected > count || expected < TPM_HEADER_SIZE) {
size = -EIO;
goto out;
}