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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>
This commit is contained in:
Jesper Juhl 2012-04-12 22:47:52 +02:00 committed by David Sterba
parent cdc6a39525
commit 4735fb2828
1 changed files with 2 additions and 0 deletions
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2
fs/btrfs/backref.c
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@ -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);
}