redonkable
/
alistair23-linux
1
0
Fork 0
Code Releases Activity

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

commit 311ae9e159 upstream.

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: Pavel Begunkov <asml.silence@gmail.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
5.4-rM2-2.2.x-imx-squashed
Pavel Begunkov 2019-11-24 11:58:24 +03:00 committed by Greg Kroah-Hartman
parent 3b2b7b8954
commit f246eedbaf
1 changed files with 14 additions and 1 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

15
fs/io_uring.c
View File

@ -1351,9 +1351,19 @@ 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);
@ -1362,6 +1372,9 @@ 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;