From 4735fb282830c0966b301dabcccf4753fa6604bb Mon Sep 17 00:00:00 2001 From: Jesper Juhl Date: Thu, 12 Apr 2012 22:47:52 +0200 Subject: [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 --- fs/btrfs/backref.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/fs/btrfs/backref.c b/fs/btrfs/backref.c index f4e90748940a..b332ff04c5ee 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); } -- 2.20.1