| Message ID | 2227988.1688721158@warthog.procyon.org.uk |
|---|---|
| State | Not Applicable |
| Headers | show |
| Series | crypto: algif/hash: Fix race between MORE and non-MORE sends | expand |
On Fri, Jul 07, 2023 at 10:12:38AM +0100, David Howells wrote: > 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@syzkaller.appspotmail.com > Link: https://lore.kernel.org/r/000000000000554b8205ffdea64e@google.com/ > Signed-off-by: David Howells <dhowells@redhat.com> > Tested-by: syzbot+689ec3afb1ef07b766b2@syzkaller.appspotmail.com > cc: Herbert Xu <herbert@gondor.apana.org.au> > cc: Paolo Abeni <pabeni@redhat.com> > cc: "David S. Miller" <davem@davemloft.net> > cc: Eric Dumazet <edumazet@google.com> > cc: Jakub Kicinski <kuba@kernel.org> > cc: linux-crypto@vger.kernel.org > cc: netdev@vger.kernel.org > --- > crypto/algif_hash.c | 4 +++- > 1 file changed, 3 insertions(+), 1 deletion(-) Patch applied. Thanks.
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);
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@syzkaller.appspotmail.com Link: https://lore.kernel.org/r/000000000000554b8205ffdea64e@google.com/ Signed-off-by: David Howells <dhowells@redhat.com> Tested-by: syzbot+689ec3afb1ef07b766b2@syzkaller.appspotmail.com cc: Herbert Xu <herbert@gondor.apana.org.au> cc: Paolo Abeni <pabeni@redhat.com> cc: "David S. Miller" <davem@davemloft.net> cc: Eric Dumazet <edumazet@google.com> cc: Jakub Kicinski <kuba@kernel.org> cc: linux-crypto@vger.kernel.org cc: netdev@vger.kernel.org --- crypto/algif_hash.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-)