lkml.org 
[lkml]   [2022]   [Jun]   [20]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    Patch in this message
    /
    From
    Subject[PATCH 5.18 067/141] io_uring: fix races with buffer table unregister
    Date
    From: Pavel Begunkov <asml.silence@gmail.com>

    [ Upstream commit d11d31fc5d8a96f707facee0babdcffaafa38de2 ]

    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: bd54b6fe3316ec ("io_uring: implement fixed buffers registration similar to fixed files")
    Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
    Signed-off-by: Sasha Levin <sashal@kernel.org>
    ---
    fs/io_uring.c | 7 +++++++
    1 file changed, 7 insertions(+)

    diff --git a/fs/io_uring.c b/fs/io_uring.c
    index 0a9f9000fc80..3d123ca028c9 100644
    --- a/fs/io_uring.c
    +++ b/fs/io_uring.c
    @@ -9495,12 +9495,19 @@ 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;
    --
    2.35.1


    \
     
     \ /
      Last update: 2022-06-20 15:01    [W:4.072 / U:0.020 seconds]
    ©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site