Patch "io_uring/net: harden multishot termination case for recv" has been added to the 6.6-stable tree

[Sasha Levin <sashal@xxxxxxxxxx>]

This is a note to let you know that I've just added the patch titled

    io_uring/net: harden multishot termination case for recv

to the 6.6-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     io_uring-net-harden-multishot-termination-case-for-r.patch
and it can be found in the queue-6.6 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.



commit cb7ff26400e66e2ce214690e6a2325fbb827511e
Author: Jens Axboe <axboe@xxxxxxxxx>
Date:   Thu Sep 26 07:08:10 2024 -0600

    io_uring/net: harden multishot termination case for recv
    
    [ Upstream commit c314094cb4cfa6fc5a17f4881ead2dfebfa717a7 ]
    
    If the recv returns zero, or an error, then it doesn't matter if more
    data has already been received for this buffer. A condition like that
    should terminate the multishot receive. Rather than pass in the
    collected return value, pass in whether to terminate or keep the recv
    going separately.
    
    Note that this isn't a bug right now, as the only way to get there is
    via setting MSG_WAITALL with multishot receive. And if an application
    does that, then -EINVAL is returned anyway. But it seems like an easy
    bug to introduce, so let's make it a bit more explicit.
    
    Link: https://github.com/axboe/liburing/issues/1246
    Cc: stable@xxxxxxxxxxxxxxx
    Fixes: b3fdea6ecb55 ("io_uring: multishot recv")
    Signed-off-by: Jens Axboe <axboe@xxxxxxxxx>
    Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>

diff --git a/io_uring/net.c b/io_uring/net.c
index cf1060fb04f43..7412904387bfa 100644
--- a/io_uring/net.c
+++ b/io_uring/net.c
@@ -930,6 +930,7 @@ int io_recv(struct io_kiocb *req, unsigned int issue_flags)
 	int ret, min_ret = 0;
 	bool force_nonblock = issue_flags & IO_URING_F_NONBLOCK;
 	size_t len = sr->len;
+	bool mshot_finished;
 
 	if (!(req->flags & REQ_F_POLLED) &&
 	    (sr->flags & IORING_RECVSEND_POLL_FIRST))
@@ -999,6 +1000,7 @@ int io_recv(struct io_kiocb *req, unsigned int issue_flags)
 		req_set_fail(req);
 	}
 
+	mshot_finished = ret <= 0;
 	if (ret > 0)
 		ret += sr->done_io;
 	else if (sr->done_io)
@@ -1006,7 +1008,7 @@ int io_recv(struct io_kiocb *req, unsigned int issue_flags)
 	else
 		io_kbuf_recycle(req, issue_flags);
 
-	if (!io_recv_finish(req, &ret, &msg, ret <= 0, issue_flags))
+	if (!io_recv_finish(req, &ret, &msg, mshot_finished, issue_flags))
 		goto retry_multishot;
 
 	return ret;