Commit 24e093b9 authored Jul 30, 2019 by Jia-Ju Bai Committed by Greg Kroah-Hartman Sep 06, 2019

fs: afs: Fix a possible null-pointer dereference in afs_put_read()



[ Upstream commit a6eed4ab5dd4bfb696c1a3f49742b8d1846a66a0 ]

In afs_read_dir(), there is an if statement on line 255 to check whether
req->pages is NULL:
	if (!req->pages)
		goto error;

If req->pages is NULL, afs_put_read() on line 337 is executed.
In afs_put_read(), req->pages[i] is used on line 195.
Thus, a possible null-pointer dereference may occur in this case.

To fix this possible bug, an if statement is added in afs_put_read() to
check req->pages.

This bug is found by a static analysis tool STCheck written by us.

Fixes: f3ddee8d ("afs: Fix directory handling")
Signed-off-by: Jia-Ju Bai <baijiaju1990@gmail.com>
Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>

parent 8e5179f9

fs/afs/file.c

+7 −5

Original line number	Diff line number	Diff line
		@@ -193,11 +193,13 @@ void afs_put_read(struct afs_read *req)
		int i;

		if (refcount_dec_and_test(&req->usage)) {
		if (req->pages) {
		for (i = 0; i < req->nr_pages; i++)
		if (req->pages[i])
		put_page(req->pages[i]);
		if (req->pages != req->array)
		kfree(req->pages);
		}
		kfree(req);
		}
		}