Re: [PATCH] crypto: drbg - set freed buffers to NULL

[Herbert Xu]

On Thu, Apr 12, 2018 at 08:40:55AM +0200, Stephan Müller wrote:
> Add the Fixes, CC stable tags.
> 
> ---8<---
> 
> During freeing of the internal buffers used by the DRBG, set the pointer
> to NULL. It is possible that the context with the freed buffers is
> reused. In case of an error during initialization where the pointers
> do not yet point to allocated memory, the NULL value prevents a double
> free.
> 
> Cc: sta...@vger.kernel.org
> Fixes: 3cfc3b9721123 ("crypto: drbg - use aligned buffers")
> Signed-off-by: Stephan Mueller 
> Reported-by: syzbot+75397ee3df5c70164...@syzkaller.appspotmail.com

Patch applied.  Thanks.
-- 
Email: Herbert Xu 
Home Page: http://gondor.apana.org.au/~herbert/
PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt

[PATCH] crypto: drbg - set freed buffers to NULL

[Stephan Müller]

Add the Fixes, CC stable tags.

---8<---

During freeing of the internal buffers used by the DRBG, set the pointer
to NULL. It is possible that the context with the freed buffers is
reused. In case of an error during initialization where the pointers
do not yet point to allocated memory, the NULL value prevents a double
free.

Cc: sta...@vger.kernel.org
Fixes: 3cfc3b9721123 ("crypto: drbg - use aligned buffers")
Signed-off-by: Stephan Mueller 
Reported-by: syzbot+75397ee3df5c70164...@syzkaller.appspotmail.com
---
 crypto/drbg.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/crypto/drbg.c b/crypto/drbg.c
index 4faa2781c964..466a112a4446 100644
--- a/crypto/drbg.c
+++ b/crypto/drbg.c
@@ -1134,8 +1134,10 @@ static inline void drbg_dealloc_state(struct drbg_state 
*drbg)
if (!drbg)
return;
kzfree(drbg->Vbuf);
+   drbg->Vbuf = NULL;
drbg->V = NULL;
kzfree(drbg->Cbuf);
+   drbg->Cbuf = NULL;
drbg->C = NULL;
kzfree(drbg->scratchpadbuf);
drbg->scratchpadbuf = NULL;
-- 
2.14.3

Re: [PATCH] crypto: drbg - set freed buffers to NULL

[Eric Biggers]

On Wed, Apr 11, 2018 at 04:31:01PM +0200, Stephan Müller wrote:
> Sorry, this time with the proper subject line.
> 
> ---8<---
> 
> During freeing of the internal buffers used by the DRBG, set the pointer
> to NULL. It is possible that the context with the freed buffers is
> reused. In case of an error during initialization where the pointers
> do not yet point to allocated memory, the NULL value prevents a double
> free.
> 
> Signed-off-by: Stephan Mueller 
> Reported-by: syzbot+75397ee3df5c70164...@syzkaller.appspotmail.com
> ---
>  crypto/drbg.c | 2 ++
>  1 file changed, 2 insertions(+)
> 
> diff --git a/crypto/drbg.c b/crypto/drbg.c
> index 4faa2781c964..466a112a4446 100644
> --- a/crypto/drbg.c
> +++ b/crypto/drbg.c
> @@ -1134,8 +1134,10 @@ static inline void drbg_dealloc_state(struct 
> drbg_state *drbg)
>   if (!drbg)
>   return;
>   kzfree(drbg->Vbuf);
> + drbg->Vbuf = NULL;
>   drbg->V = NULL;
>   kzfree(drbg->Cbuf);
> + drbg->Cbuf = NULL;
>   drbg->C = NULL;
>   kzfree(drbg->scratchpadbuf);
>   drbg->scratchpadbuf = NULL;

Can you please add Fixes and Cc stable?

- Eric

[PATCH] crypto: drbg - set freed buffers to NULL

[Stephan Müller]

Sorry, this time with the proper subject line.

---8<---

During freeing of the internal buffers used by the DRBG, set the pointer
to NULL. It is possible that the context with the freed buffers is
reused. In case of an error during initialization where the pointers
do not yet point to allocated memory, the NULL value prevents a double
free.

Signed-off-by: Stephan Mueller 
Reported-by: syzbot+75397ee3df5c70164...@syzkaller.appspotmail.com
---
 crypto/drbg.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/crypto/drbg.c b/crypto/drbg.c
index 4faa2781c964..466a112a4446 100644
--- a/crypto/drbg.c
+++ b/crypto/drbg.c
@@ -1134,8 +1134,10 @@ static inline void drbg_dealloc_state(struct drbg_state 
*drbg)
if (!drbg)
return;
kzfree(drbg->Vbuf);
+   drbg->Vbuf = NULL;
drbg->V = NULL;
kzfree(drbg->Cbuf);
+   drbg->Cbuf = NULL;
drbg->C = NULL;
kzfree(drbg->scratchpadbuf);
drbg->scratchpadbuf = NULL;
-- 
2.14.3