> I'm pretty certain this is the same as: > > https://syzkaller.appspot.com/bug?extid=689ec3afb1ef07b766b2 > > as I sometimes see the same trace when running the reproducer from there. > --- > > #syz test: git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master This crash does not have a reproducer. I cannot test it. > > crypto: algif/hash: Fix race between MORE and non-MORE sends > > The 'MSG_MORE' state of the previous sendmsg() is fetched without the > socket lock held, so two sendmsg calls can race. This can be seen with a > large sendfile() as that now does a series of sendmsg() calls, and if a > write() comes in on the same socket at an inopportune time, it can flip the > state. > > Fix this by moving the fetch of ctx->more inside the socket lock. > > Fixes: c662b043cdca ("crypto: af_alg/hash: Support MSG_SPLICE_PAGES") > Reported-by: syzbot+689ec3afb1ef07b766b2@xxxxxxxxxxxxxxxxxxxxxxxxx > Link: https://lore.kernel.org/r/000000000000554b8205ffdea64e@xxxxxxxxxx/ > Signed-off-by: David Howells <dhowells@xxxxxxxxxx> > cc: Herbert Xu <herbert@xxxxxxxxxxxxxxxxxxx> > cc: Paolo Abeni <pabeni@xxxxxxxxxx> > cc: "David S. Miller" <davem@xxxxxxxxxxxxx> > cc: Eric Dumazet <edumazet@xxxxxxxxxx> > cc: Jakub Kicinski <kuba@xxxxxxxxxx> > cc: linux-crypto@xxxxxxxxxxxxxxx > cc: netdev@xxxxxxxxxxxxxxx > > diff --git a/crypto/algif_hash.c b/crypto/algif_hash.c > index 0ab43e149f0e..82c44d4899b9 100644 > --- a/crypto/algif_hash.c > +++ b/crypto/algif_hash.c > @@ -68,13 +68,15 @@ static int hash_sendmsg(struct socket *sock, struct msghdr *msg, > struct hash_ctx *ctx = ask->private; > ssize_t copied = 0; > size_t len, max_pages, npages; > - bool continuing = ctx->more, need_init = false; > + bool continuing, need_init = false; > int err; > > max_pages = min_t(size_t, ALG_MAX_PAGES, > DIV_ROUND_UP(sk->sk_sndbuf, PAGE_SIZE)); > > lock_sock(sk); > + continuing = ctx->more; > + > if (!continuing) { > /* Discard a previous request that wasn't marked MSG_MORE. */ > hash_free_result(sk, ctx); >
