6.6-stable review patch. If anyone has any objections, please let me know.
------------------
From: Pavel Begunkov asml.silence@gmail.com
Commit bcc87d978b834c298bbdd9c52454c5d0a946e97e upstream.
Syz reports a problem, which boils down to NULL vs IS_ERR inconsistent error handling in io_alloc_pbuf_ring().
KASAN: null-ptr-deref in range [0x0000000000000000-0x0000000000000007] RIP: 0010:__io_remove_buffers+0xac/0x700 io_uring/kbuf.c:341 Call Trace: <TASK> io_put_bl io_uring/kbuf.c:378 [inline] io_destroy_buffers+0x14e/0x490 io_uring/kbuf.c:392 io_ring_ctx_free+0xa00/0x1070 io_uring/io_uring.c:2613 io_ring_exit_work+0x80f/0x8a0 io_uring/io_uring.c:2844 process_one_work kernel/workqueue.c:3231 [inline] process_scheduled_works+0xa2c/0x1830 kernel/workqueue.c:3312 worker_thread+0x86d/0xd40 kernel/workqueue.c:3390 kthread+0x2f0/0x390 kernel/kthread.c:389 ret_from_fork+0x4b/0x80 arch/x86/kernel/process.c:147 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244
Cc: stable@vger.kernel.org Reported-by: syzbot+2074b1a3d447915c6f1c@syzkaller.appspotmail.com Fixes: 87585b05757dc ("io_uring/kbuf: use vm_insert_pages() for mmap'ed pbuf ring") Signed-off-by: Pavel Begunkov asml.silence@gmail.com Link: https://lore.kernel.org/r/c5f9df20560bd9830401e8e48abc029e7cfd9f5e.172132923... Signed-off-by: Jens Axboe axboe@kernel.dk Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- io_uring/kbuf.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-)
--- a/io_uring/kbuf.c +++ b/io_uring/kbuf.c @@ -510,8 +510,10 @@ static int io_alloc_pbuf_ring(struct io_ ring_size = reg->ring_entries * sizeof(struct io_uring_buf_ring);
bl->buf_ring = io_pages_map(&bl->buf_pages, &bl->buf_nr_pages, ring_size); - if (!bl->buf_ring) + if (IS_ERR(bl->buf_ring)) { + bl->buf_ring = NULL; return -ENOMEM; + } bl->is_mapped = 1; bl->is_mmap = 1; return 0;