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

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: f3ddee8 ("afs: Fix directory handling") Signed-off-by: Jia-Ju Bai <[email protected]> Signed-off-by: David Howells <[email protected]>
jangid · Jul 30, 2019 · a6eed4a · a6eed4a
1 parent 4a46fdb
commit a6eed4a
Showing 1 changed file with 7 additions and 5 deletions.
diff --git 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);
 	}
 }