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tpm: st33zp24: fix potential buffer overruns caused by bit glitches on the bus

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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>
This commit is contained in:
Jeremy Boone 2018-02-08 12:29:09 -08:00 committed by James Morris
parent 9b8cb28d7c
commit 6d24cd186d
1 changed files with 2 additions and 2 deletions
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4
drivers/char/tpm/st33zp24/st33zp24.c
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@ -457,7 +457,7 @@ static int st33zp24_recv(struct tpm_chip *chip, unsigned char *buf,
size_t count) size_t count)
{ {
int size = 0; int size = 0;
int expected; u32 expected;
if (!chip) if (!chip)
return -EBUSY; return -EBUSY;
@ -474,7 +474,7 @@ static int st33zp24_recv(struct tpm_chip *chip, unsigned char *buf,
} }
expected = be32_to_cpu(*(__be32 *)(buf + 2)); expected = be32_to_cpu(*(__be32 *)(buf + 2));
if (expected > count) { if (expected > count || expected < TPM_HEADER_SIZE) {
size = -EIO; size = -EIO;
goto out; goto out;
} }