6.5-stable review patch. If anyone has any objections, please let me know.
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From: Pavel Begunkov asml.silence@gmail.com
commit c21a8027ad8a68c340d0d58bf1cc61dcb0bc4d2f upstream.
When using selected buffer feature, io_uring delays data iter setup until later. If io_setup_async_msg() is called before that it might see not correctly setup iterator. Pre-init nr_segs and judge from its state whether we repointing.
Cc: stable@vger.kernel.org Reported-by: syzbot+a4c6e5ef999b68b26ed1@syzkaller.appspotmail.com Fixes: 0455d4ccec548 ("io_uring: add POLL_FIRST support for send/sendmsg and recv/recvmsg") Signed-off-by: Pavel Begunkov asml.silence@gmail.com Link: https://lore.kernel.org/r/0000000000002770be06053c7757@google.com Signed-off-by: Jens Axboe axboe@kernel.dk Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- io_uring/net.c | 5 +++++ 1 file changed, 5 insertions(+)
--- a/io_uring/net.c +++ b/io_uring/net.c @@ -183,6 +183,10 @@ static int io_setup_async_msg(struct io_ memcpy(async_msg, kmsg, sizeof(*kmsg)); if (async_msg->msg.msg_name) async_msg->msg.msg_name = &async_msg->addr; + + if ((req->flags & REQ_F_BUFFER_SELECT) && !async_msg->msg.msg_iter.nr_segs) + return -EAGAIN; + /* if were using fast_iov, set it to the new one */ if (iter_is_iovec(&kmsg->msg.msg_iter) && !kmsg->free_iov) { size_t fast_idx = iter_iov(&kmsg->msg.msg_iter) - kmsg->fast_iov; @@ -542,6 +546,7 @@ static int io_recvmsg_copy_hdr(struct io struct io_async_msghdr *iomsg) { iomsg->msg.msg_name = &iomsg->addr; + iomsg->msg.msg_iter.nr_segs = 0;
#ifdef CONFIG_COMPAT if (req->ctx->compat)