jffs2: Fix possible null-pointer dereferences in jffs2_add_frag_to_fragtree()

In jffs2_add_frag_to_fragtree(), there is an if statement on line 223 to
check whether "this" is NULL:
    if (this)

When "this" is NULL, it is used at several places, such as on line 249:
    if (this->node)
and on line 260:
    if (newfrag->ofs > this->ofs)

Thus possible null-pointer dereferences may occur.

To fix these bugs, -EINVAL is returned when "this" is NULL.

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

Signed-off-by: Jia-Ju Bai <baijiaju1990@gmail.com>
Signed-off-by: Richard Weinberger <richard@nod.at>

1 files changed, 1 insertions, 1 deletions

diff --git a/fs/jffs2/nodelist.c b/fs/jffs2/nodelist.c
index b86c78d178c6..021a4a2190ee 100644
--- a/fs/jffs2/nodelist.c
+++ b/fs/jffs2/nodelist.c
@@ -226,7 +226,7 @@ static int jffs2_add_frag_to_fragtree(struct jffs2_sb_info *c, struct rb_root *r
                 lastend = this->ofs + this->size;
         } else {
                 dbg_fragtree2("lookup gave no frag\n");
-                lastend = 0;
+                return -EINVAL;
         }
 
         /* See if we ran off the end of the fragtree */