From: Eric Biggers <ebiggers@xxxxxxxxxx>
It was forgotten to increase DH_KPP_SECRET_MIN_SIZE to include 'q_size',
causing an out-of-bounds write of 4 bytes in crypto_dh_encode_key(), and
an out-of-bounds read of 4 bytes in crypto_dh_decode_key(). Fix it.
Also add a BUG_ON() if crypto_dh_encode_key() doesn't exactly fill the
buffer, as that would have found this bug without resorting to KASAN.
Reported-by: syzbot+6d38d558c25b53b8f4ed@xxxxxxxxxxxxxxxxxxxxxxxxx
Fixes: e3fe0ae12962 ("crypto: dh - add public key verification test")
Signed-off-by: Eric Biggers <ebiggers@xxxxxxxxxx>
---
crypto/dh_helper.c | 5 +++--
1 file changed, 3 insertions(+), 2 deletions(-)
diff --git a/crypto/dh_helper.c b/crypto/dh_helper.c
index a7de3d9ce5ace..87ad6e2e87644 100644
--- a/crypto/dh_helper.c
+++ b/crypto/dh_helper.c
@@ -14,7 +14,7 @@
#include <crypto/dh.h>
#include <crypto/kpp.h>
-#define DH_KPP_SECRET_MIN_SIZE (sizeof(struct kpp_secret) + 3 * sizeof(int))
+#define DH_KPP_SECRET_MIN_SIZE (sizeof(struct kpp_secret) + 4 * sizeof(int))
static inline u8 *dh_pack_data(void *dst, const void *src, size_t size)
{
@@ -61,7 +61,8 @@ int crypto_dh_encode_key(char *buf, unsigned int len, const struct dh *params)
ptr = dh_pack_data(ptr, params->key, params->key_size);
ptr = dh_pack_data(ptr, params->p, params->p_size);
ptr = dh_pack_data(ptr, params->q, params->q_size);
- dh_pack_data(ptr, params->g, params->g_size);
+ ptr = dh_pack_data(ptr, params->g, params->g_size);
+ BUG_ON(ptr != (u8 *)buf + len);
return 0;
}
--
2.18.0
