Re: FAILED: patch "[PATCH] io_uring/zcrx: fix area release on registration failure" failed to apply to 6.15-stable tree

[Jens Axboe <axboe@kernel.dk>]

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On 6/20/25 4:34 AM, gregkh@linuxfoundation.org wrote:
> 
> The patch below does not apply to the 6.15-stable tree.
> If someone wants it applied there, or to any other stable or longterm
> tree, then please email the backport, including the original git commit
> id to <stable@vger.kernel.org>.
> 
> To reproduce the conflict and resubmit, you may use the following commands:
> 
> git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-6.15.y
> git checkout FETCH_HEAD
> git cherry-pick -x 0ec33c81d9c7342f03864101ddb2e717a0cce03e
> # <resolve conflicts, build, test, etc.>
> git commit -s
> git send-email --to '<stable@vger.kernel.org>' --in-reply-to '2025062018-ahead-armory-59ac@gregkh' --subject-prefix 'PATCH 6.15.y' HEAD^..

Here's one for 6.15-stable.

-- 
Jens Axboe

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From 4a1b0f1b90d14e69430c5aa7682988d35eeb8b69 Mon Sep 17 00:00:00 2001
From: Pavel Begunkov <asml.silence@gmail.com>
Date: Tue, 27 May 2025 18:07:33 +0100
Subject: [PATCH] io_uring/zcrx: fix area release on registration failure

Commit 0ec33c81d9c7342f03864101ddb2e717a0cce03e upstream.

On area registration failure there might be no ifq set and it's not safe
to access area->ifq in the release path without checking it first.

Cc: stable@vger.kernel.org
Fixes: f12ecf5e1c5ec ("io_uring/zcrx: fix late dma unmap for a dead dev")
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/bc02878678a5fec28bc77d33355cdba735418484.1748365640.git.asml.silence@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
---
 io_uring/zcrx.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/io_uring/zcrx.c b/io_uring/zcrx.c
index fe86606b9f30..71036d31b30f 100644
--- a/io_uring/zcrx.c
+++ b/io_uring/zcrx.c
@@ -187,7 +187,8 @@ static void io_free_rbuf_ring(struct io_zcrx_ifq *ifq)
 
 static void io_zcrx_free_area(struct io_zcrx_area *area)
 {
-	io_zcrx_unmap_area(area->ifq, area);
+	if (area->ifq)
+		io_zcrx_unmap_area(area->ifq, area);
 
 	kvfree(area->freelist);
 	kvfree(area->nia.niovs);
-- 
2.50.0