lkml.org 
[lkml]   [2019]   [Jul]   [23]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
From
Subject[PATCH] fs: kernfs: Fix possible null-pointer dereferences in kernfs_path_from_node_locked()
Date
In kernfs_path_from_node_locked(), there is an if statement on line 147
to check whether buf is NULL:
if (buf)

When buf is NULL, it is used on line 151:
len += strlcpy(buf + len, parent_str, ...)
and line 158:
len += strlcpy(buf + len, "/", ...)
and line 160:
len += strlcpy(buf + len, kn->name, ...)

Thus, possible null-pointer dereferences may occur.

To fix these possible bugs, buf is checked before being used.
If it is NULL, -EINVAL is returned.

These bugs are found by a static analysis tool STCheck written by us.

Signed-off-by: Jia-Ju Bai <baijiaju1990@gmail.com>
---
fs/kernfs/dir.c | 6 ++++--
1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/fs/kernfs/dir.c b/fs/kernfs/dir.c
index a387534c9577..9b01f6ce1d79 100644
--- a/fs/kernfs/dir.c
+++ b/fs/kernfs/dir.c
@@ -137,6 +137,9 @@ static int kernfs_path_from_node_locked(struct kernfs_node *kn_to,
if (kn_from == kn_to)
return strlcpy(buf, "/", buflen);

+ if (!buf)
+ return -EINVAL;
+
common = kernfs_common_ancestor(kn_from, kn_to);
if (WARN_ON(!common))
return -EINVAL;
@@ -144,8 +147,7 @@ static int kernfs_path_from_node_locked(struct kernfs_node *kn_to,
depth_to = kernfs_depth(common, kn_to);
depth_from = kernfs_depth(common, kn_from);

- if (buf)
- buf[0] = '\0';
+ buf[0] = '\0';

for (i = 0; i < depth_from; i++)
len += strlcpy(buf + len, parent_str,
--
2.17.0
\
 
 \ /
  Last update: 2019-07-24 04:23    [W:0.754 / U:0.736 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site