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io_uring: fix races with buffer table unregister 

Fixed buffer table quiesce might unlock ->uring_lock, potentially
letting new requests to be submitted, don't allow those requests to
use the table as they will race with unregistration.

Reported-and-tested-by: van fantasy <g1042620637@gmail.com>
Fixes: bd54b6fe33 ("io_uring: implement fixed buffers registration similar to fixed files")
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
This commit is contained in:
Pavel Begunkov 2022-06-13 06:30:06 +01:00
parent b0380bf6da
commit d11d31fc5d
1 changed files with 7 additions and 0 deletions
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7
fs/io_uring.c
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@ -10680,12 +10680,19 @@ static void __io_sqe_buffers_unregister(struct io_ring_ctx *ctx)
static int io_sqe_buffers_unregister(struct io_ring_ctx *ctx)
{
unsigned nr = ctx->nr_user_bufs;
int ret;
if (!ctx->buf_data)
return -ENXIO;
/*
* Quiesce may unlock ->uring_lock, and while it's not held
* prevent new requests using the table.
*/
ctx->nr_user_bufs = 0;
ret = io_rsrc_ref_quiesce(ctx->buf_data, ctx);
ctx->nr_user_bufs = nr;
if (!ret)
__io_sqe_buffers_unregister(ctx);
return ret;