[PATCH] tpm: fix use after free in tpm2_load_context

[PATCH] tpm: fix use after free in tpm2_load_context

[Tadeusz Struk]

If load context command returns with TPM2_RC_HANDLE or
TPM2_RC_REFERENCE_H0 then we have use after free in
line 114 and double free in 117.

Fixes: 4d57856a21ed2 ("tpm2: add session handle context saving and restoring to the space code")

Signed-off-by: Tadeusz Struk <tadeusz.struk-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org>
---
 drivers/char/tpm/tpm2-space.c |    3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/char/tpm/tpm2-space.c b/drivers/char/tpm/tpm2-space.c
index 4e4014eabdb9..6122d3276f72 100644
--- a/drivers/char/tpm/tpm2-space.c
+++ b/drivers/char/tpm/tpm2-space.c
@@ -102,8 +102,9 @@ static int tpm2_load_context(struct tpm_chip *chip, u8 *buf,
 		 * TPM_RC_REFERENCE_H0 means the session has been
 		 * flushed outside the space
 		 */
-		rc = -ENOENT;
+		*handle = 0;
 		tpm_buf_destroy(&tbuf);
+		return -ENOENT;
 	} else if (rc > 0) {
 		dev_warn(&chip->dev, "%s: failed with a TPM error 0x%04X\n",
 			 __func__, rc);


------------------------------------------------------------------------------
Check out the vibrant tech community on one of the world's most
engaging tech sites, Slashdot.org! http://sdm.link/slashdot

Re: [PATCH] tpm: fix use after free in tpm2_load_context

[Jarkko Sakkinen]

On Wed, May 09, 2018 at 11:55:35AM -0700, Tadeusz Struk wrote:
> If load context command returns with TPM2_RC_HANDLE or
> TPM2_RC_REFERENCE_H0 then we have use after free in
> line 114 and double free in 117.
> 
> Fixes: 4d57856a21ed2 ("tpm2: add session handle context saving and restoring to the space code")
> 
> Signed-off-by: Tadeusz Struk <tadeusz.struk-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org>

Thank you, appreciate this!

Reviewed-by: Jarkko Sakkinen <jarkko.sakkinen-VuQAYsv1563Yd54FQh9/CA@public.gmane.org>

/Jarkko

------------------------------------------------------------------------------
Check out the vibrant tech community on one of the world's most
engaging tech sites, Slashdot.org! http://sdm.link/slashdot