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io_uring: io_wq_submit_work() should not touch req->rw

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I've been chasing a weird and obscure crash that was userspace stack
corruption, and finally narrowed it down to a bit flip that made a
stack address invalid. io_wq_submit_work() unconditionally flips
the req->rw.ki_flags IOCB_NOWAIT bit, but since it's a generic work
handler, this isn't valid. Normal read/write operations own that
part of the request, on other types it could be something else.

Move the IOCB_NOWAIT clear to the read/write handlers where it belongs.

Signed-off-by: Jens Axboe <axboe@kernel.dk>
This commit is contained in:
Jens Axboe 2019-12-18 12:19:41 -07:00
parent 7c504e6520
commit fd6c2e4c06
1 changed files with 8 additions and 3 deletions
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11
fs/io_uring.c
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@ -1817,6 +1817,10 @@ static int io_read(struct io_kiocb *req, struct io_kiocb **nxt,
return ret;
}
/* Ensure we clear previously set non-block flag */
if (!force_nonblock)
req->rw.ki_flags &= ~IOCB_NOWAIT;
file = req->file;
io_size = ret;
if (req->flags & REQ_F_LINK)
@ -1906,6 +1910,10 @@ static int io_write(struct io_kiocb *req, struct io_kiocb **nxt,
return ret;
}
/* Ensure we clear previously set non-block flag */
if (!force_nonblock)
req->rw.ki_flags &= ~IOCB_NOWAIT;
file = kiocb->ki_filp;
io_size = ret;
if (req->flags & REQ_F_LINK)
@ -3274,9 +3282,6 @@ static void io_wq_submit_work(struct io_wq_work **workptr)
struct io_kiocb *nxt = NULL;
int ret = 0;
/* Ensure we clear previously set non-block flag */
req->rw.ki_flags &= ~IOCB_NOWAIT;
if (work->flags & IO_WQ_WORK_CANCEL)
ret = -ECANCELED;