[PATCH 6.6 116/244] io_uring/kbuf: check for buffer list readiness after NULL check

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6.6-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Jens Axboe <axboe@xxxxxxxxx>

[ Upstream commit 9865346b7e8374b57f1c3ccacdc77846c6352ff4 ]

Move the buffer list 'is_ready' check below the validity check for
the buffer list for a given group.

Fixes: 5cf4f52e6d8a ("io_uring: free io_buffer_list entries via RCU")
Reported-by: Dan Carpenter <dan.carpenter@xxxxxxxxxx>
Signed-off-by: Jens Axboe <axboe@xxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
 io_uring/kbuf.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/io_uring/kbuf.c b/io_uring/kbuf.c
index 12eec4778c5b1..e8516f3bbbaaa 100644
--- a/io_uring/kbuf.c
+++ b/io_uring/kbuf.c
@@ -743,6 +743,8 @@ void *io_pbuf_get_address(struct io_ring_ctx *ctx, unsigned long bgid)
 
 	bl = __io_buffer_get_list(ctx, smp_load_acquire(&ctx->io_bl), bgid);
 
+	if (!bl || !bl->is_mmap)
+		return NULL;
 	/*
 	 * Ensure the list is fully setup. Only strictly needed for RCU lookup
 	 * via mmap, and in that case only for the array indexed groups. For
@@ -750,8 +752,6 @@ void *io_pbuf_get_address(struct io_ring_ctx *ctx, unsigned long bgid)
 	 */
 	if (!smp_load_acquire(&bl->is_ready))
 		return NULL;
-	if (!bl || !bl->is_mmap)
-		return NULL;
 
 	return bl->buf_ring;
 }
-- 
2.42.0







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