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io_uring: fix potential crash issue due to io_get_req failure 

Sometimes io_get_req will return a NUL, then we need to do the
correct error handling, otherwise it will cause the kernel null
pointer exception.

Fixes: 4fe2c96315 ("io_uring: add support for link with drain")
Signed-off-by: Jackie Liu <liuyun01@kylinos.cn>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
alistair/sunxi64-5.4-dsi
Jackie Liu 2019-09-18 17:25:52 +08:00 committed by Jens Axboe
parent 6cc47d1d2a
commit a1041c27b6
1 changed files with 6 additions and 0 deletions
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6
fs/io_uring.c
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@ -2364,12 +2364,15 @@ static int io_submit_sqes(struct io_ring_ctx *ctx, struct sqe_submit *sqes,
if (link && (sqes[i].sqe->flags & IOSQE_IO_DRAIN)) {
if (!shadow_req) {
shadow_req = io_get_req(ctx, NULL);
if (unlikely(!shadow_req))
goto out;
shadow_req->flags |= (REQ_F_IO_DRAIN | REQ_F_SHADOW_DRAIN);
refcount_dec(&shadow_req->refs);
}
shadow_req->sequence = sqes[i].sequence;
}
out:
if (unlikely(mm_fault)) {
io_cqring_add_event(ctx, sqes[i].sqe->user_data,
-EFAULT);
@ -2551,12 +2554,15 @@ static int io_ring_submit(struct io_ring_ctx *ctx, unsigned int to_submit,
if (link && (s.sqe->flags & IOSQE_IO_DRAIN)) {
if (!shadow_req) {
shadow_req = io_get_req(ctx, NULL);
if (unlikely(!shadow_req))
goto out;
shadow_req->flags |= (REQ_F_IO_DRAIN | REQ_F_SHADOW_DRAIN);
refcount_dec(&shadow_req->refs);
}
shadow_req->sequence = s.sequence;
}
out:
s.has_user = true;
s.needs_lock = false;
s.needs_fixed_file = false;