Jesper Juhl
2012-Apr-12 20:47 UTC
[PATCH] Btrfs: Make free_ipath() deal gracefully with NULL pointers
Make free_ipath() behave like most other freeing functions in the
kernel and gracefully do nothing when passed a NULL pointer.
Besides this making the bahaviour consistent with functions such as
kfree(), vfree(), btrfs_free_path() etc etc, it also fixes a real NULL
deref issue in fs/btrfs/ioctl.c::btrfs_ioctl_ino_to_path(). In that
function we have this code:
...
ipath = init_ipath(size, root, path);
if (IS_ERR(ipath)) {
ret = PTR_ERR(ipath);
ipath = NULL;
goto out;
}
...
out:
btrfs_free_path(path);
free_ipath(ipath);
...
If we ever take the true branch of that ''if'' statement
we''ll end up
passing a NULL pointer to free_ipath() which will subsequently
dereference it and we''ll go "Boom" :-(
This patch will avoid that.
Signed-off-by: Jesper Juhl <jj@chaosbits.net>
---
fs/btrfs/backref.c | 2 ++
1 file changed, 2 insertions(+)
diff --git a/fs/btrfs/backref.c b/fs/btrfs/backref.c
index f4e9074..b332ff0 100644
--- a/fs/btrfs/backref.c
+++ b/fs/btrfs/backref.c
@@ -1414,6 +1414,8 @@ struct inode_fs_paths *init_ipath(s32 total_bytes, struct
btrfs_root *fs_root,
void free_ipath(struct inode_fs_paths *ipath)
{
+ if (!ipath)
+ return;
kfree(ipath->fspath);
kfree(ipath);
}
--
1.7.10
--
Jesper Juhl <jj@chaosbits.net> http://www.chaosbits.net/
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