[ 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: f3ddee8dc4e2 ("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 --- fs/afs/file.c | 12 +++++++----- 1 file changed, 7 insertions(+), 5 deletions(-)
diff --git a/fs/afs/file.c b/fs/afs/file.c index 8fd7d3b9a1b1f..87beabc7114ee 100644 --- a/fs/afs/file.c +++ b/fs/afs/file.c @@ -191,11 +191,13 @@ void afs_put_read(struct afs_read *req) int i;
if (refcount_dec_and_test(&req->usage)) { - 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); + 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); } }