gfs2_fh_to_parent() array overflow

[Adrian Bunk <bunk@kernel.org>]

The Coverity checker spotted the following array overflow caused by
commit 34c0d154243dd913c5690ae6ceb9557017429b9c:


include/linux/exportfs.h contains:

<--  snip  -->

...
struct fid {
...
                __u32 raw[6];
        };
};

<--  snip  -->


fs/gfs2/ops_export.c contains:

<--  snip  -->

...
static struct dentry *gfs2_fh_to_parent(struct super_block *sb, struct fid *fid,
                int fh_len, int fh_type)
{
        struct gfs2_inum_host parent;
        __be32 *fh = (__force __be32 *)fid->raw;  <------------

        switch (fh_type) {
        case GFS2_LARGE_FH_SIZE:
        case GFS2_OLD_FH_SIZE:
                parent.no_formal_ino = ((u64)be32_to_cpu(fh[4])) << 32;
                parent.no_formal_ino |= be32_to_cpu(fh[5]);
                parent.no_addr = ((u64)be32_to_cpu(fh[6])) << 32;
                                                   ^^^^^
                parent.no_addr |= be32_to_cpu(fh[7]);
...                                           ^^^^^

<--  snip  -->


cu
Adrian

-- 

       "Is there not promise of rain?" Ling Tan asked suddenly out
        of the darkness. There had been need of rain for many days.
       "Only a promise," Lao Er said.
                                       Pearl S. Buck - Dragon Seed