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io_uring/rsrc: ignore dummy_ubuf for buffer cloning

Message ID 45120dbb-beee-4718-a8b8-ef5755909c0a@kernel.dk (mailing list archive)
State New
Headers show
Series io_uring/rsrc: ignore dummy_ubuf for buffer cloning | expand

Commit Message

Jens Axboe Oct. 16, 2024, 1:11 p.m. UTC
For placeholder buffers, &dummy_ubuf is assigned which is a static
value. When buffers are attempted cloned, don't attempt to grab a
reference to it, as we both don't need it and it'll actively fail as
dummy_ubuf doesn't have a valid reference count setup.

Link: https://lore.kernel.org/io-uring/Zw8dkUzsxQ5LgAJL@ly-workstation/
Reported-by: Lai, Yi <yi1.lai@linux.intel.com>
Fixes: 7cc2a6eadcd7 ("io_uring: add IORING_REGISTER_COPY_BUFFERS method")
Signed-off-by: Jens Axboe <axboe@kernel.dk>

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diff mbox series

Patch

diff --git a/io_uring/rsrc.c b/io_uring/rsrc.c
index 33a3d156a85b..6f3b6de230bd 100644
--- a/io_uring/rsrc.c
+++ b/io_uring/rsrc.c
@@ -1176,7 +1176,8 @@  static int io_clone_buffers(struct io_ring_ctx *ctx, struct io_ring_ctx *src_ctx
 	for (i = 0; i < nbufs; i++) {
 		struct io_mapped_ubuf *src = src_ctx->user_bufs[i];
 
-		refcount_inc(&src->refs);
+		if (src != &dummy_ubuf)
+			refcount_inc(&src->refs);
 		user_bufs[i] = src;
 	}