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authorJiri Slaby <jslaby@suse.cz>2016-12-15 14:31:01 +0100
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2017-03-30 09:35:20 +0200
commitf8a62dbc790239d9cb8bb8757f43a9d2e09f747c (patch)
treed5d5a025e3b1c77b448c197b4c2c03f62ba4d30f
parent540d6d756ff82a23eb5bb73aa8149bab15eb407a (diff)
crypto: algif_hash - avoid zero-sized array
commit 6207119444595d287b1e9e83a2066c17209698f3 upstream. With this reproducer: struct sockaddr_alg alg = { .salg_family = 0x26, .salg_type = "hash", .salg_feat = 0xf, .salg_mask = 0x5, .salg_name = "digest_null", }; int sock, sock2; sock = socket(AF_ALG, SOCK_SEQPACKET, 0); bind(sock, (struct sockaddr *)&alg, sizeof(alg)); sock2 = accept(sock, NULL, NULL); setsockopt(sock, SOL_ALG, ALG_SET_KEY, "\x9b\xca", 2); accept(sock2, NULL, NULL); ==== 8< ======== 8< ======== 8< ======== 8< ==== one can immediatelly see an UBSAN warning: UBSAN: Undefined behaviour in crypto/algif_hash.c:187:7 variable length array bound value 0 <= 0 CPU: 0 PID: 15949 Comm: syz-executor Tainted: G E 4.4.30-0-default #1 ... Call Trace: ... [<ffffffff81d598fd>] ? __ubsan_handle_vla_bound_not_positive+0x13d/0x188 [<ffffffff81d597c0>] ? __ubsan_handle_out_of_bounds+0x1bc/0x1bc [<ffffffffa0e2204d>] ? hash_accept+0x5bd/0x7d0 [algif_hash] [<ffffffffa0e2293f>] ? hash_accept_nokey+0x3f/0x51 [algif_hash] [<ffffffffa0e206b0>] ? hash_accept_parent_nokey+0x4a0/0x4a0 [algif_hash] [<ffffffff8235c42b>] ? SyS_accept+0x2b/0x40 It is a correct warning, as hash state is propagated to accept as zero, but creating a zero-length variable array is not allowed in C. Fix this as proposed by Herbert -- do "?: 1" on that site. No sizeof or similar happens in the code there, so we just allocate one byte even though we do not use the array. Signed-off-by: Jiri Slaby <jslaby@suse.cz> Cc: Herbert Xu <herbert@gondor.apana.org.au> Cc: "David S. Miller" <davem@davemloft.net> (maintainer:CRYPTO API) Reported-by: Sasha Levin <sasha.levin@oracle.com> Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au> Cc: Arnd Bergmann <arnd@arndb.de> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
-rw-r--r--crypto/algif_hash.c2
1 files changed, 1 insertions, 1 deletions
diff --git a/crypto/algif_hash.c b/crypto/algif_hash.c
index 68a5ceaa04c8..8d8b3eeba725 100644
--- a/crypto/algif_hash.c
+++ b/crypto/algif_hash.c
@@ -184,7 +184,7 @@ static int hash_accept(struct socket *sock, struct socket *newsock, int flags)
struct alg_sock *ask = alg_sk(sk);
struct hash_ctx *ctx = ask->private;
struct ahash_request *req = &ctx->req;
- char state[crypto_ahash_statesize(crypto_ahash_reqtfm(req))];
+ char state[crypto_ahash_statesize(crypto_ahash_reqtfm(req)) ? : 1];
struct sock *sk2;
struct alg_sock *ask2;
struct hash_ctx *ctx2;