Commit b4a72c05 authored by Wojciech Lukowicz's avatar Wojciech Lukowicz Committed by Jens Axboe
Browse files

io_uring: fix memory leak when removing provided buffers 



When removing provided buffers, io_buffer structs are not being disposed
of, leading to a memory leak. They can't be freed individually, because
they are allocated in page-sized groups. They need to be added to some
free list instead, such as io_buffers_cache. All callers already hold
the lock protecting it, apart from when destroying buffers, so had to
extend the lock there.

Fixes: cc3cec83 ("io_uring: speedup provided buffer handling")
Signed-off-by: default avatarWojciech Lukowicz <wlukowicz01@gmail.com>
Link: https://lore.kernel.org/r/20230401195039.404909-2-wlukowicz01@gmail.com


Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
parent c0921e51

io_uring/io_uring.c

+1 −1
Original line number Diff line number Diff line
@@ -2789,8 +2789,8 @@ static __cold void io_ring_ctx_free(struct io_ring_ctx *ctx) 
	io_eventfd_unregister(ctx);

	io_alloc_cache_free(&ctx->apoll_cache, io_apoll_cache_free);

	io_alloc_cache_free(&ctx->netmsg_cache, io_netmsg_cache_free);

	mutex_unlock(&ctx->uring_lock);

	io_destroy_buffers(ctx);

	mutex_unlock(&ctx->uring_lock);

	if (ctx->sq_creds)

		put_cred(ctx->sq_creds);

	if (ctx->submitter_task)

io_uring/kbuf.c

+4 −1
Original line number Diff line number Diff line
@@ -228,11 +228,14 @@ static int __io_remove_buffers(struct io_ring_ctx *ctx, 
		return i;

	}



	/* protects io_buffers_cache */

	lockdep_assert_held(&ctx->uring_lock);



	while (!list_empty(&bl->buf_list)) {

		struct io_buffer *nxt;



		nxt = list_first_entry(&bl->buf_list, struct io_buffer, list);

		list_del(&nxt->list);

		list_move(&nxt->list, &ctx->io_buffers_cache);

		if (++i == nbufs)

			return i;

		cond_resched();