crypto: drbg - set freed buffers to NULL
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Message ID 20316956.hJt0ZTxKTH@positron.chronox.de
State Superseded
Delegated to: Herbert Xu
Headers show

Commit Message

Stephan Mueller April 11, 2018, 2:31 p.m. UTC
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 <smueller@chronox.de>
Reported-by: syzbot+75397ee3df5c70164154@syzkaller.appspotmail.com
---
 crypto/drbg.c | 2 ++
 1 file changed, 2 insertions(+)

Comments

Eric Biggers April 11, 2018, 5:29 p.m. UTC | #1
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 <smueller@chronox.de>
> Reported-by: syzbot+75397ee3df5c70164154@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
diff mbox

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;