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

Stephan Müller
2018-04-11T14:31:45Z

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;
--
2.14.3