On Mon, Dec 11, 2017 at 12:15:17PM -0800, Eric Biggers wrote:
From: Eric Biggers ebiggers@google.com
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") Cc: stable@vger.kernel.org # v4.2+ Signed-off-by: Eric Biggers ebiggers@google.com
Patch applied. Thanks.