crypto: algif_skcipher - Fixed blocking recvmsg

As most (all?) users of algif_skcipher are single-threaded and
therefore always write before reading from an algif_skcipher
socket, they never block and exercise that code-path.

It turns out that code path doesn't even work because we never
reload ctx->used after waking up so we never even see the new
data and immediately return an error (and a loud WARN_ON).

This patch fixes this by always reloading ctx->used.

Reported-by: Stephan Mueller <smueller@chronox.de>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Acked-by: Stephan Mueller <smueller@chronox.de>

diff --git a/crypto/algif_skcipher.c b/crypto/algif_skcipher.c
index 3438996..f80e652 100644 (file)
--- a/crypto/algif_skcipher.c
+++ b/crypto/algif_skcipher.c
@@ -448,14 +448,13 @@ static int skcipher_recvmsg(struct kiocb *unused, struct socket *sock,
                        while (!sg->length)
                                sg++;
 
-                       used = ctx->used;
-                       if (!used) {
+                       if (!ctx->used) {
                                err = skcipher_wait_for_data(sk, flags);
                                if (err)
                                        goto unlock;
                        }
 
-                       used = min_t(unsigned long, used, seglen);
+                       used = min_t(unsigned long, ctx->used, seglen);
 
                        used = af_alg_make_sg(&ctx->rsgl, from, used, 1);
                        err = used;