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authorStephan Mueller <smueller@chronox.de>2017-11-29 12:02:23 +0100
committerHerbert Xu <herbert@gondor.apana.org.au>2017-12-11 22:29:54 +1100
commit11edb555966ed2c66c533d17c604f9d7e580a829 (patch)
treedae6e140f8c759c9d966e7cb0e25b5c69f0dae7b /crypto
parent2b4f27c36bcd46e820ddb9a8e6fe6a63fa4250b8 (diff)
download96b-common-11edb555966ed2c66c533d17c604f9d7e580a829.tar.gz
crypto: af_alg - wait for data at beginning of recvmsg
The wait for data is a non-atomic operation that can sleep and therefore potentially release the socket lock. The release of the socket lock allows another thread to modify the context data structure. The waiting operation for new data therefore must be called at the beginning of recvmsg. This prevents a race condition where checks of the members of the context data structure are performed by recvmsg while there is a potential for modification of these values. Fixes: e870456d8e7c ("crypto: algif_skcipher - overhaul memory management") Fixes: d887c52d6ae4 ("crypto: algif_aead - overhaul memory management") Reported-by: syzbot <syzkaller@googlegroups.com> Cc: <stable@vger.kernel.org> # v4.14+ Signed-off-by: Stephan Mueller <smueller@chronox.de> Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Diffstat (limited to 'crypto')
-rw-r--r--crypto/af_alg.c6
-rw-r--r--crypto/algif_aead.c6
-rw-r--r--crypto/algif_skcipher.c6
3 files changed, 12 insertions, 6 deletions
diff --git a/crypto/af_alg.c b/crypto/af_alg.c
index 358749c38894..f1a2caf1b59b 100644
--- a/crypto/af_alg.c
+++ b/crypto/af_alg.c
@@ -1137,12 +1137,6 @@ int af_alg_get_rsgl(struct sock *sk, struct msghdr *msg, int flags,
if (!af_alg_readable(sk))
break;
- if (!ctx->used) {
- err = af_alg_wait_for_data(sk, flags);
- if (err)
- return err;
- }
-
seglen = min_t(size_t, (maxsize - len),
msg_data_left(msg));
diff --git a/crypto/algif_aead.c b/crypto/algif_aead.c
index 805f485ddf1b..c8a32bef208a 100644
--- a/crypto/algif_aead.c
+++ b/crypto/algif_aead.c
@@ -111,6 +111,12 @@ static int _aead_recvmsg(struct socket *sock, struct msghdr *msg,
size_t usedpages = 0; /* [in] RX bufs to be used from user */
size_t processed = 0; /* [in] TX bufs to be consumed */
+ if (!ctx->used) {
+ err = af_alg_wait_for_data(sk, flags);
+ if (err)
+ return err;
+ }
+
/*
* Data length provided by caller via sendmsg/sendpage that has not
* yet been processed.
diff --git a/crypto/algif_skcipher.c b/crypto/algif_skcipher.c
index 30cff827dd8f..6fb595cd63ac 100644
--- a/crypto/algif_skcipher.c
+++ b/crypto/algif_skcipher.c
@@ -72,6 +72,12 @@ static int _skcipher_recvmsg(struct socket *sock, struct msghdr *msg,
int err = 0;
size_t len = 0;
+ if (!ctx->used) {
+ err = af_alg_wait_for_data(sk, flags);
+ if (err)
+ return err;
+ }
+
/* Allocate cipher request for current operation. */
areq = af_alg_alloc_areq(sk, sizeof(struct af_alg_async_req) +
crypto_skcipher_reqsize(tfm));