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io_uring: fix race condition reading SQE data 

When punting to workers the SQE gets copied after the initial try.
There is a race condition between reading SQE data for the initial try
and copying it for punting it to the workers.

For example io_rw_done calls kiocb->ki_complete even if it was prepared
for IORING_OP_FSYNC (and would be NULL).

The easiest solution for now is to alway prepare again in the worker.

req->file is safe to prepare though as long as it is checked before use.

Signed-off-by: Stefan Bühler <source@stbuehler.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
This commit is contained in:
Stefan Bühler 2019-05-11 19:08:01 +02:00 committed by Jens Axboe
parent a13f065550
commit e2033e33cb
1 changed files with 2 additions and 15 deletions
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17
fs/io_uring.c
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@ -329,9 +329,8 @@ struct io_kiocb {
#define REQ_F_IOPOLL_COMPLETED 2 /* polled IO has completed */
#define REQ_F_FIXED_FILE 4 /* ctx owns file */
#define REQ_F_SEQ_PREV 8 /* sequential with previous */
#define REQ_F_PREPPED 16 /* prep already done */
#define REQ_F_IO_DRAIN 32 /* drain existing IO first */
#define REQ_F_IO_DRAINED 64 /* drain done */
#define REQ_F_IO_DRAIN 16 /* drain existing IO first */
#define REQ_F_IO_DRAINED 32 /* drain done */
u64 user_data;
u32 error; /* iopoll result from callback */
u32 sequence;
@ -896,9 +895,6 @@ static int io_prep_rw(struct io_kiocb *req, const struct sqe_submit *s,
if (!req->file)
return -EBADF;
/* For -EAGAIN retry, everything is already prepped */
if (req->flags & REQ_F_PREPPED)
return 0;
if (force_nonblock && !io_file_supports_async(req->file))
force_nonblock = false;
@ -941,7 +937,6 @@ static int io_prep_rw(struct io_kiocb *req, const struct sqe_submit *s,
return -EINVAL;
kiocb->ki_complete = io_complete_rw;
}
req->flags |= REQ_F_PREPPED;
return 0;
}
@ -1227,16 +1222,12 @@ static int io_prep_fsync(struct io_kiocb *req, const struct io_uring_sqe *sqe)
if (!req->file)
return -EBADF;
/* Prep already done (EAGAIN retry) */
if (req->flags & REQ_F_PREPPED)
return 0;
if (unlikely(ctx->flags & IORING_SETUP_IOPOLL))
return -EINVAL;
if (unlikely(sqe->addr || sqe->ioprio || sqe->buf_index))
return -EINVAL;
req->flags |= REQ_F_PREPPED;
return 0;
}
@ -1277,16 +1268,12 @@ static int io_prep_sfr(struct io_kiocb *req, const struct io_uring_sqe *sqe)
if (!req->file)
return -EBADF;
/* Prep already done (EAGAIN retry) */
if (req->flags & REQ_F_PREPPED)
return 0;
if (unlikely(ctx->flags & IORING_SETUP_IOPOLL))
return -EINVAL;
if (unlikely(sqe->addr || sqe->ioprio || sqe->buf_index))
return -EINVAL;
req->flags |= REQ_F_PREPPED;
return ret;
}