sysfs: Fix oops in sysfs_drop_dentry on x86_64

Fix oops on x86_64 caused by the dereference of dir in
sysfs_drop_dentry() made before checking if dir is not NULL
(cf. http://marc.info/?l=linux-kernel&m=118151626704924&w=2).

Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
Signed-off-by: Tejun Heo <htejun@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

diff --git a/fs/sysfs/inode.c b/fs/sysfs/inode.c
index 732fd7f371e0d7467e35242037f1771809c4c1e7..ee31bf369a88b1eaf647aae9ea4c30695140dcc2 100644 (file)
--- a/fs/sysfs/inode.c
+++ b/fs/sysfs/inode.c
@@ -285,7 +285,7 @@ void sysfs_drop_dentry(struct sysfs_dirent *sd)
 int sysfs_hash_and_remove(struct dentry * dir, const char * name)
 {
        struct sysfs_dirent **pos, *sd;
-       struct sysfs_dirent *parent_sd = dir->d_fsdata;
+       struct sysfs_dirent *parent_sd;
        int found = 0;
 
        if (!dir)
@@ -295,6 +295,7 @@ int sysfs_hash_and_remove(struct dentry * dir, const char * name)
                /* no inode means this hasn't been made visible yet */
                return -ENOENT;
 
+       parent_sd = dir->d_fsdata;
        mutex_lock_nested(&dir->d_inode->i_mutex, I_MUTEX_PARENT);
        for (pos = &parent_sd->s_children; *pos; pos = &(*pos)->s_sibling) {
                sd = *pos;