Commit 311ae9e1 authored by Pavel Begunkov's avatar Pavel Begunkov Committed by Jens Axboe

io_uring: fix dead-hung for non-iter fixed rw

Read/write requests to devices without implemented read/write_iter
using fixed buffers can cause general protection fault, which totally
hangs a machine.

io_import_fixed() initialises iov_iter with bvec, but loop_rw_iter()
accesses it as iovec, dereferencing random address.

kmap() page by page in this case

Cc: stable@vger.kernel.org
Signed-off-by: default avatarPavel Begunkov <asml.silence@gmail.com>
Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
parent f8e85cf2
......@@ -1622,9 +1622,19 @@ static ssize_t loop_rw_iter(int rw, struct file *file, struct kiocb *kiocb,
return -EAGAIN;
while (iov_iter_count(iter)) {
struct iovec iovec = iov_iter_iovec(iter);
struct iovec iovec;
ssize_t nr;
if (!iov_iter_is_bvec(iter)) {
iovec = iov_iter_iovec(iter);
} else {
/* fixed buffers import bvec */
iovec.iov_base = kmap(iter->bvec->bv_page)
+ iter->iov_offset;
iovec.iov_len = min(iter->count,
iter->bvec->bv_len - iter->iov_offset);
}
if (rw == READ) {
nr = file->f_op->read(file, iovec.iov_base,
iovec.iov_len, &kiocb->ki_pos);
......@@ -1633,6 +1643,9 @@ static ssize_t loop_rw_iter(int rw, struct file *file, struct kiocb *kiocb,
iovec.iov_len, &kiocb->ki_pos);
}
if (iov_iter_is_bvec(iter))
kunmap(iter->bvec->bv_page);
if (nr < 0) {
if (!ret)
ret = nr;
......
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