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| author | Kees Cook <keescook@chromium.org> | 2019-04-01 12:06:07 -0700 |
|---|---|---|
| committer | Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com> | 2019-06-24 23:57:49 +0300 |
| commit | 782779b60faa2fc7ff609ac8ef938260fd792c0f (patch) | |
| tree | 56c4d8f22366f244910bd96c4ed6e1b6b553cc7d /drivers/char | |
| parent | c88e40e07cd967dcdf37321a63ab6e8b0d881100 (diff) | |
| download | linux-782779b60faa2fc7ff609ac8ef938260fd792c0f.tar.gz linux-782779b60faa2fc7ff609ac8ef938260fd792c0f.tar.bz2 linux-782779b60faa2fc7ff609ac8ef938260fd792c0f.zip | |
tpm: Actually fail on TPM errors during "get random"
A "get random" may fail with a TPM error, but those codes were returned
as-is to the caller, which assumed the result was the number of bytes
that had been written to the target buffer, which could lead to a kernel
heap memory exposure and over-read.
This fixes tpm1_get_random() to mask positive TPM errors into -EIO, as
before.
[ 18.092103] tpm tpm0: A TPM error (379) occurred attempting get random
[ 18.092106] usercopy: Kernel memory exposure attempt detected from SLUB object 'kmalloc-64' (offset 0, size 379)!
Link: https://bugzilla.redhat.com/show_bug.cgi?id=1650989
Reported-by: Phil Baker <baker1tex@gmail.com>
Reported-by: Craig Robson <craig@zhatt.com>
Fixes: 7aee9c52d7ac ("tpm: tpm1: rewrite tpm1_get_random() using tpm_buf structure")
Cc: Laura Abbott <labbott@redhat.com>
Cc: Tomas Winkler <tomas.winkler@intel.com>
Cc: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
Cc: stable@vger.kernel.org
Signed-off-by: Kees Cook <keescook@chromium.org>
Reviewed-by: Tomas Winkler <tomas.winkler@intel.com>
Tested-by: Bartosz Szczepanek <bsz@semihalf.com>
Reviewed-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
Signed-off-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
Diffstat (limited to 'drivers/char')
| -rw-r--r-- | drivers/char/tpm/tpm1-cmd.c | 7 | ||||
| -rw-r--r-- | drivers/char/tpm/tpm2-cmd.c | 7 |
2 files changed, 10 insertions, 4 deletions
diff --git a/drivers/char/tpm/tpm1-cmd.c b/drivers/char/tpm/tpm1-cmd.c index 85dcf2654d11..faacbe1ffa1a 100644 --- a/drivers/char/tpm/tpm1-cmd.c +++ b/drivers/char/tpm/tpm1-cmd.c @@ -510,7 +510,7 @@ struct tpm1_get_random_out { * * Return: * * number of bytes read - * * -errno or a TPM return code otherwise + * * -errno (positive TPM return codes are masked to -EIO) */ int tpm1_get_random(struct tpm_chip *chip, u8 *dest, size_t max) { @@ -531,8 +531,11 @@ int tpm1_get_random(struct tpm_chip *chip, u8 *dest, size_t max) rc = tpm_transmit_cmd(chip, &buf, sizeof(out->rng_data_len), "attempting get random"); - if (rc) + if (rc) { + if (rc > 0) + rc = -EIO; goto out; + } out = (struct tpm1_get_random_out *)&buf.data[TPM_HEADER_SIZE]; diff --git a/drivers/char/tpm/tpm2-cmd.c b/drivers/char/tpm/tpm2-cmd.c index 4de49924cfc4..d103545e4055 100644 --- a/drivers/char/tpm/tpm2-cmd.c +++ b/drivers/char/tpm/tpm2-cmd.c @@ -297,7 +297,7 @@ struct tpm2_get_random_out { * * Return: * size of the buffer on success, - * -errno otherwise + * -errno otherwise (positive TPM return codes are masked to -EIO) */ int tpm2_get_random(struct tpm_chip *chip, u8 *dest, size_t max) { @@ -324,8 +324,11 @@ int tpm2_get_random(struct tpm_chip *chip, u8 *dest, size_t max) offsetof(struct tpm2_get_random_out, buffer), "attempting get random"); - if (err) + if (err) { + if (err > 0) + err = -EIO; goto out; + } out = (struct tpm2_get_random_out *) &buf.data[TPM_HEADER_SIZE]; |