tpm_tis: fix potential buffer overruns caused by bit glitches on the bus
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>
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@ -270,7 +270,8 @@ static int tpm_tis_recv(struct tpm_chip *chip, u8 *buf, size_t count)
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{
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{
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struct tpm_tis_data *priv = dev_get_drvdata(&chip->dev);
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struct tpm_tis_data *priv = dev_get_drvdata(&chip->dev);
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int size = 0;
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int size = 0;
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int expected, status;
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int status;
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u32 expected;
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if (count < TPM_HEADER_SIZE) {
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if (count < TPM_HEADER_SIZE) {
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size = -EIO;
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size = -EIO;
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@ -285,7 +286,7 @@ static int tpm_tis_recv(struct tpm_chip *chip, u8 *buf, size_t count)
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}
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}
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expected = be32_to_cpu(*(__be32 *) (buf + 2));
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expected = be32_to_cpu(*(__be32 *) (buf + 2));
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if (expected > count) {
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if (expected > count || expected < TPM_HEADER_SIZE) {
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size = -EIO;
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size = -EIO;
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goto out;
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goto out;
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}
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}
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