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FAILED: patch "[PATCH] io_uring/kbuf: reallocate buf lists on upgrade" failed to apply to 6.13-stable tree

PATCH In review [email protected] 2 participants 5 messages Feb 18, 2025 – Feb 19, 2025

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Stable branch io_uring
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[email protected]

author maintainer
#0 lore raw

The patch below does not apply to the 6.13-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 <[email protected]>.

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-6.13.y
git checkout FETCH_HEAD
git cherry-pick -x 8802766324e1f5d414a81ac43365c20142e85603
# <resolve conflicts, build, test, etc.>
git commit -s
git send-email --to '<[email protected]>' --in-reply-to '2025021855-snugly-hacked-a8fa@gregkh' --subject-prefix 'PATCH 6.13.y' HEAD^..

Possible dependencies:

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From 8802766324e1f5d414a81ac43365c20142e85603 Mon Sep 17 00:00:00 2001
From: Pavel Begunkov <[email protected]>
Date: Wed, 12 Feb 2025 13:46:46 +0000
Subject: [PATCH] io_uring/kbuf: reallocate buf lists on upgrade

IORING_REGISTER_PBUF_RING can reuse an old struct io_buffer_list if it was created for legacy selected buffer and has been emptied. It violates the requirement that most of the field should stay stable after publish. Always reallocate it instead.

Cc [email protected]
Reported-by Pumpkin Chang <[email protected]>
Fixes 2fcabce2d7d34 ("io_uring: disallow mixed provided buffer group registrations")
Signed-off-by Pavel Begunkov <[email protected]>
Signed-off-by Jens Axboe <[email protected]>
io_uring/kbuf.c +12 -4
index 04bf493eecae..8e72de7712ac 100644
@@ -415,6 +415,13 @@ void io_destroy_buffers(struct io_ring_ctx *ctx)
 	}
 }
 
+static void io_destroy_bl(struct io_ring_ctx *ctx, struct io_buffer_list *bl)
+{
+	scoped_guard(mutex, &ctx->mmap_lock)
+		WARN_ON_ONCE(xa_erase(&ctx->io_bl_xa, bl->bgid) != bl);
+	io_put_bl(ctx, bl);
+}
+
 int io_remove_buffers_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe)
 {
 	struct io_provide_buf *p = io_kiocb_to_cmd(req, struct io_provide_buf);

@@ -636,12 +643,13 @@ int io_register_pbuf_ring(struct io_ring_ctx *ctx, void __user *arg)
 		/* if mapped buffer ring OR classic exists, don't allow */
 		if (bl->flags & IOBL_BUF_RING || !list_empty(&bl->buf_list))
 			return -EEXIST;
-	} else {
-		free_bl = bl = kzalloc(sizeof(*bl), GFP_KERNEL);
-		if (!bl)
-			return -ENOMEM;
+		io_destroy_bl(ctx, bl);
 	}
 
+	free_bl = bl = kzalloc(sizeof(*bl), GFP_KERNEL);
+	if (!bl)
+		return -ENOMEM;
+
 	mmap_offset = (unsigned long)reg.bgid << IORING_OFF_PBUF_SHIFT;
 	ring_size = flex_array_size(br, bufs, reg.ring_entries);
#1 lore raw

PATCH 1/1 io_uring/kbuf: reallocate buf lists on upgrade

[ upstream commit 8802766324e1f5d414a81ac43365c20142e85603 ]

IORING_REGISTER_PBUF_RING can reuse an old struct io_buffer_list if it was created for legacy selected buffer and has been emptied. It violates the requirement that most of the field should stay stable after publish. Always reallocate it instead.

Cc [email protected]
Reported-by Pumpkin Chang <[email protected]>
Fixes 2fcabce2d7d34 ("io_uring: disallow mixed provided buffer group registrations")
Signed-off-by Pavel Begunkov <[email protected]>
Signed-off-by Jens Axboe <[email protected]>
---
 io_uring/kbuf.c | 15 +++++++++++----
 1 file changed, 11 insertions(+), 4 deletions(-)
io_uring/kbuf.c +11 -4
index eec5eb7de843..e1895952066e 100644
@@ -420,6 +420,12 @@ void io_destroy_buffers(struct io_ring_ctx *ctx)
 	}
 }
 
+static void io_destroy_bl(struct io_ring_ctx *ctx, struct io_buffer_list *bl)
+{
+	xa_erase(&ctx->io_bl_xa, bl->bgid);
+	io_put_bl(ctx, bl);
+}
+
 int io_remove_buffers_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe)
 {
 	struct io_provide_buf *p = io_kiocb_to_cmd(req, struct io_provide_buf);

@@ -717,12 +723,13 @@ int io_register_pbuf_ring(struct io_ring_ctx *ctx, void __user *arg)
 		/* if mapped buffer ring OR classic exists, don't allow */
 		if (bl->flags & IOBL_BUF_RING || !list_empty(&bl->buf_list))
 			return -EEXIST;
-	} else {
-		free_bl = bl = kzalloc(sizeof(*bl), GFP_KERNEL);
-		if (!bl)
-			return -ENOMEM;
+		io_destroy_bl(ctx, bl);
 	}
 
+	free_bl = bl = kzalloc(sizeof(*bl), GFP_KERNEL);
+	if (!bl)
+		return -ENOMEM;
+
 	if (!(reg.flags & IOU_PBUF_RING_MMAP))
 		ret = io_pin_pbuf_ring(&reg, bl);
 	else
Signature · 1 line
2.48.1
#2 lore raw

Re: [PATCH 6.12.y 6.13.y] io_uring/kbuf: reallocate buf lists on upgrade

Quoted 6 lines · Pavel Begunkov

[ upstream commit 8802766324e1f5d414a81ac43365c20142e85603 ]

IORING_REGISTER_PBUF_RING can reuse an old struct io_buffer_list if it was created for legacy selected buffer and has been emptied. It violates the requirement that most of the field should stay stable after publish. Always reallocate it instead.

Just a note that it should apply to 6.13 and 6.12, can you pick it for both of them?

Signature · 1 line
Pavel Begunkov
author maintainer
#3 lore raw

Re: [PATCH 6.12.y 6.13.y] io_uring/kbuf: reallocate buf lists on upgrade

Quoted 10 lines · Pavel Begunkov
Quoted 6 lines · Pavel Begunkov

[ upstream commit 8802766324e1f5d414a81ac43365c20142e85603 ]

IORING_REGISTER_PBUF_RING can reuse an old struct io_buffer_list if it was created for legacy selected buffer and has been emptied. It violates the requirement that most of the field should stay stable after publish. Always reallocate it instead.

Just a note that it should apply to 6.13 and 6.12, can you pick it for both of them?

Now done, thanks!

greg k-h

#4 lore raw

Re: [PATCH 6.12.y 6.13.y] io_uring/kbuf: reallocate buf lists on upgrade

Quoted 9 lines · Greg KH
Quoted 8 lines · Pavel Begunkov
Quoted 6 lines · Pavel Begunkov

[ upstream commit 8802766324e1f5d414a81ac43365c20142e85603 ]

IORING_REGISTER_PBUF_RING can reuse an old struct io_buffer_list if it was created for legacy selected buffer and has been emptied. It violates the requirement that most of the field should stay stable after publish. Always reallocate it instead.

Quoted 4 lines
Quoted 2 lines

Just a note that it should apply to 6.13 and 6.12, can you pick it for both of them?

Now done, thanks!

Great, thanks

Signature · 1 line
Pavel Begunkov