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io_uring: don't re-import iovecs from callbacks

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We can't re-import or modify iterators from iocb callbacks, it's not
safe as it might be reverted and/or reexpanded while unwinding stack.
It's also not safe to resubmit as io-wq thread will race with stack
undwinding for the iterator and other data.

Disallow resubmission from callbacks, it can fail some cases that were
handled before, but the possibility of such a failure was a part of the
API from the beginning and so it should be fine.

Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Pavel Begunkov 2022-06-03 13:17:04 +01:00 committed by Greg Kroah-Hartman
parent 6029f86740
commit 57d01bcae7
1 changed files with 0 additions and 39 deletions
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39
fs/io_uring.c
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@ -2579,45 +2579,6 @@ static void io_complete_rw_common(struct kiocb *kiocb, long res,
#ifdef CONFIG_BLOCK
static bool io_resubmit_prep(struct io_kiocb *req, int error)
{
struct iovec inline_vecs[UIO_FASTIOV], *iovec = inline_vecs;
ssize_t ret = -ECANCELED;
struct iov_iter iter;
int rw;
if (error) {
ret = error;
goto end_req;
}
switch (req->opcode) {
case IORING_OP_READV:
case IORING_OP_READ_FIXED:
case IORING_OP_READ:
rw = READ;
break;
case IORING_OP_WRITEV:
case IORING_OP_WRITE_FIXED:
case IORING_OP_WRITE:
rw = WRITE;
break;
default:
printk_once(KERN_WARNING "io_uring: bad opcode in resubmit %d\n",
req->opcode);
goto end_req;
}
if (!req->async_data) {
ret = io_import_iovec(rw, req, &iovec, &iter, false);
if (ret < 0)
goto end_req;
ret = io_setup_async_rw(req, iovec, inline_vecs, &iter, false);
if (!ret)
return true;
kfree(iovec);
} else {
return true;
}
end_req:
req_set_fail_links(req);
return false;
}