diff options
| author | Eric Biggers <ebiggers@google.com> | 2017-12-11 12:15:17 -0800 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2018-01-10 09:27:09 +0100 |
| commit | 869994e0bd2911ed07169e11362c479e4c98fd78 (patch) | |
| tree | 86382557470106ed072419167655a260f4642a8b /crypto | |
| parent | 0b72e17dde6e2468dfed6ce2a558bc2fc806cd2f (diff) | |
crypto: chacha20poly1305 - validate the digest size
commit e57121d08c38dabec15cf3e1e2ad46721af30cae upstream.
If the rfc7539 template was instantiated with a hash algorithm with
digest size larger than 16 bytes (POLY1305_DIGEST_SIZE), then the digest
overran the 'tag' buffer in 'struct chachapoly_req_ctx', corrupting the
subsequent memory, including 'cryptlen'. This caused a crash during
crypto_skcipher_decrypt().
Fix it by, when instantiating the template, requiring that the
underlying hash algorithm has the digest size expected for Poly1305.
Reproducer:
#include <linux/if_alg.h>
#include <sys/socket.h>
#include <unistd.h>
int main()
{
int algfd, reqfd;
struct sockaddr_alg addr = {
.salg_type = "aead",
.salg_name = "rfc7539(chacha20,sha256)",
};
unsigned char buf[32] = { 0 };
algfd = socket(AF_ALG, SOCK_SEQPACKET, 0);
bind(algfd, (void *)&addr, sizeof(addr));
setsockopt(algfd, SOL_ALG, ALG_SET_KEY, buf, sizeof(buf));
reqfd = accept(algfd, 0, 0);
write(reqfd, buf, 16);
read(reqfd, buf, 16);
}
Reported-by: syzbot <syzkaller@googlegroups.com>
Fixes: 71ebc4d1b27d ("crypto: chacha20poly1305 - Add a ChaCha20-Poly1305 AEAD construction, RFC7539")
Signed-off-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'crypto')
| -rw-r--r-- | crypto/chacha20poly1305.c | 6 |
1 files changed, 5 insertions, 1 deletions
diff --git a/crypto/chacha20poly1305.c b/crypto/chacha20poly1305.c index 99c3cce01290..0214600ba071 100644 --- a/crypto/chacha20poly1305.c +++ b/crypto/chacha20poly1305.c @@ -600,6 +600,11 @@ static int chachapoly_create(struct crypto_template *tmpl, struct rtattr **tb, CRYPTO_ALG_TYPE_AHASH_MASK); if (IS_ERR(poly)) return PTR_ERR(poly); + poly_hash = __crypto_hash_alg_common(poly); + + err = -EINVAL; + if (poly_hash->digestsize != POLY1305_DIGEST_SIZE) + goto out_put_poly; err = -ENOMEM; inst = kzalloc(sizeof(*inst) + sizeof(*ctx), GFP_KERNEL); @@ -608,7 +613,6 @@ static int chachapoly_create(struct crypto_template *tmpl, struct rtattr **tb, ctx = aead_instance_ctx(inst); ctx->saltlen = CHACHAPOLY_IV_SIZE - ivsize; - poly_hash = __crypto_hash_alg_common(poly); err = crypto_init_ahash_spawn(&ctx->poly, poly_hash, aead_crypto_instance(inst)); if (err) |