4.4-stable review patch. If anyone has any objections, please let me know.
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From: Eric Biggers ebiggers@google.com
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
--- crypto/chacha20poly1305.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-)
--- a/crypto/chacha20poly1305.c +++ b/crypto/chacha20poly1305.c @@ -600,6 +600,11 @@ static int chachapoly_create(struct cryp 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 cryp
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)