From b6d972f6898308fbe7e693bf8d44ebfdb1cd2dc4 Mon Sep 17 00:00:00 2001 From: David Howells Date: Fri, 16 Jun 2023 12:10:32 +0100 Subject: crypto: af_alg/hash: Fix recvmsg() after sendmsg(MSG_MORE) If an AF_ALG socket bound to a hashing algorithm is sent a zero-length message with MSG_MORE set and then recvmsg() is called without first sending another message without MSG_MORE set to end the operation, an oops will occur because the crypto context and result doesn't now get set up in advance because hash_sendmsg() now defers that as long as possible in the hope that it can use crypto_ahash_digest() - and then because the message is zero-length, it the data wrangling loop is skipped. Fix this by handling zero-length sends at the top of the hash_sendmsg() function. If we're not continuing the previous sendmsg(), then just ignore the send (hash_recvmsg() will invent something when called); if we are continuing, then we finalise the request at this point if MSG_MORE is not set to get any error here, otherwise the send is of no effect and can be ignored. Whilst we're at it, remove the code to create a kvmalloc'd scatterlist if we get more than ALG_MAX_PAGES - this shouldn't happen. Fixes: c662b043cdca ("crypto: af_alg/hash: Support MSG_SPLICE_PAGES") Reported-by: syzbot+13a08c0bf4d212766c3c@syzkaller.appspotmail.com Link: https://lore.kernel.org/r/000000000000b928f705fdeb873a@google.com/ Reported-by: syzbot+14234ccf6d0ef629ec1a@syzkaller.appspotmail.com Link: https://lore.kernel.org/r/000000000000c047db05fdeb8790@google.com/ Reported-by: syzbot+4e2e47f32607d0f72d43@syzkaller.appspotmail.com Link: https://lore.kernel.org/r/000000000000bcca3205fdeb87fb@google.com/ Reported-by: syzbot+472626bb5e7c59fb768f@syzkaller.appspotmail.com Link: https://lore.kernel.org/r/000000000000b55d8805fdeb8385@google.com/ Signed-off-by: David Howells Reported-and-tested-by: syzbot+6efc50cc1f8d718d6cb7@syzkaller.appspotmail.com cc: Jens Axboe cc: Matthew Wilcox Acked-by: Herbert Xu Link: https://lore.kernel.org/r/427646.1686913832@warthog.procyon.org.uk Signed-off-by: Jakub Kicinski --- crypto/algif_hash.c | 38 +++++++++++++++++++++++++------------- 1 file changed, 25 insertions(+), 13 deletions(-) diff --git a/crypto/algif_hash.c b/crypto/algif_hash.c index dfb048cefb60..0ab43e149f0e 100644 --- a/crypto/algif_hash.c +++ b/crypto/algif_hash.c @@ -76,13 +76,30 @@ static int hash_sendmsg(struct socket *sock, struct msghdr *msg, lock_sock(sk); if (!continuing) { - if ((msg->msg_flags & MSG_MORE)) - hash_free_result(sk, ctx); + /* Discard a previous request that wasn't marked MSG_MORE. */ + hash_free_result(sk, ctx); + if (!msg_data_left(msg)) + goto done; /* Zero-length; don't start new req */ need_init = true; + } else if (!msg_data_left(msg)) { + /* + * No data - finalise the prev req if MSG_MORE so any error + * comes out here. + */ + if (!(msg->msg_flags & MSG_MORE)) { + err = hash_alloc_result(sk, ctx); + if (err) + goto unlock_free; + ahash_request_set_crypt(&ctx->req, NULL, + ctx->result, 0); + err = crypto_wait_req(crypto_ahash_final(&ctx->req), + &ctx->wait); + if (err) + goto unlock_free; + } + goto done_more; } - ctx->more = false; - while (msg_data_left(msg)) { ctx->sgl.sgt.sgl = ctx->sgl.sgl; ctx->sgl.sgt.nents = 0; @@ -93,15 +110,6 @@ static int hash_sendmsg(struct socket *sock, struct msghdr *msg, if (npages == 0) goto unlock_free; - if (npages > ARRAY_SIZE(ctx->sgl.sgl)) { - err = -ENOMEM; - ctx->sgl.sgt.sgl = - kvmalloc(array_size(npages, - sizeof(*ctx->sgl.sgt.sgl)), - GFP_KERNEL); - if (!ctx->sgl.sgt.sgl) - goto unlock_free; - } sg_init_table(ctx->sgl.sgl, npages); ctx->sgl.need_unpin = iov_iter_extract_will_pin(&msg->msg_iter); @@ -150,7 +158,9 @@ static int hash_sendmsg(struct socket *sock, struct msghdr *msg, af_alg_free_sg(&ctx->sgl); } +done_more: ctx->more = msg->msg_flags & MSG_MORE; +done: err = 0; unlock: release_sock(sk); @@ -158,6 +168,8 @@ unlock: unlock_free: af_alg_free_sg(&ctx->sgl); + hash_free_result(sk, ctx); + ctx->more = false; goto unlock; } -- cgit