[PATCH] crypto: ecc: fix NULL pointer dereferencing in ecc_gen_privkey()

[PATCH] crypto: ecc: fix NULL pointer dereferencing in ecc_gen_privkey()

[Roman Smirnov]

ecc_get_curve() can return NULL. It is necessary to check
for NULL before dereferencing.

Found by Linux Verification Center (linuxtesting.org) with Svace.

Signed-off-by: Roman Smirnov <r.smirnov@omp.ru>
Reviewed-by: Sergey Shtylyov <s.shtylyov@omp.ru>
---
 crypto/ecc.c | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/crypto/ecc.c b/crypto/ecc.c
index f53fb4d6af99..fd63e354895b 100644
--- a/crypto/ecc.c
+++ b/crypto/ecc.c
@@ -1471,9 +1471,14 @@ int ecc_gen_privkey(unsigned int curve_id, unsigned int ndigits, u64 *privkey)
 	const struct ecc_curve *curve = ecc_get_curve(curve_id);
 	u64 priv[ECC_MAX_DIGITS];
 	unsigned int nbytes = ndigits << ECC_DIGITS_TO_BYTES_SHIFT;
-	unsigned int nbits = vli_num_bits(curve->n, ndigits);
+	unsigned int nbits;
 	int err;
 
+	if (!curve)
+		return -EINVAL;
+
+	nbits = vli_num_bits(curve->n, ndigits);
+
 	/* Check that N is included in Table 1 of FIPS 186-4, section 6.1.1 */
 	if (nbits < 160 || ndigits > ARRAY_SIZE(priv))
 		return -EINVAL;
-- 
2.34.1

Re: [PATCH] crypto: ecc: fix NULL pointer dereferencing in ecc_gen_privkey()

[Herbert Xu]

On Thu, Mar 07, 2024 at 10:13:18AM +0300, Roman Smirnov wrote:
> ecc_get_curve() can return NULL. It is necessary to check
> for NULL before dereferencing.
> 
> Found by Linux Verification Center (linuxtesting.org) with Svace.
> 
> Signed-off-by: Roman Smirnov <r.smirnov@omp.ru>
> Reviewed-by: Sergey Shtylyov <s.shtylyov@omp.ru>
> ---
>  crypto/ecc.c | 7 ++++++-
>  1 file changed, 6 insertions(+), 1 deletion(-)

Please point me to the exact code path where this can happen.

Thanks,
-- 
Email: Herbert Xu <herbert@gondor.apana.org.au>
Home Page: http://gondor.apana.org.au/~herbert/
PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt

Re: [PATCH] crypto: ecc: fix NULL pointer dereferencing in ecc_gen_privkey()

[Roman Smirnov]

On Thu, 21 Mar 2024 17:54:44 +0800, Herbert Xu wrote:
> On Thu, Mar 07, 2024 at 10:13:18AM +0300, Roman Smirnov wrote:
> > ecc_get_curve() can return NULL. It is necessary to check
> > for NULL before dereferencing.
> > 
> > Found by Linux Verification Center (linuxtesting.org) with Svace.
> > 
> > Signed-off-by: Roman Smirnov <r.smirnov@omp.ru>
> > Reviewed-by: Sergey Shtylyov <s.shtylyov@omp.ru>
> > ---
> >  crypto/ecc.c | 7 ++++++-
> >  1 file changed, 6 insertions(+), 1 deletion(-)
> 
> Please point me to the exact code path where this can happen.

I didn't find a specific path. Several places in the file have this
check:

ecc_make_pub_key()
crypto_ecdh_shared_secret()

I thought it was needed in this place too.