staging: vboxsf: fix dereference of pointer dentry before it is null checked

Currently the pointer dentry is being dereferenced before it is
being null checked.  Fix this by only dereferencing dentry once
we know it is not null.

Addresses-Coverity: ("Dereference before null check")
Fixes: 919e29678792 ("staging: Add VirtualBox guest shared folder (vboxsf) support")
Signed-off-by: Colin Ian King <colin.king@canonical.com>
Link: https://lore.kernel.org/r/20191105175108.79824-1-colin.king@canonical.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/staging/vboxsf/utils.c b/drivers/staging/vboxsf/utils.c
index 1870b69c824e2804a0cca1f33832e29383c3a20b..34a49e6f74fced5b29f91e449986c3273d2ce865 100644 (file)
--- a/drivers/staging/vboxsf/utils.c
+++ b/drivers/staging/vboxsf/utils.c
@@ -174,7 +174,7 @@ int vboxsf_stat_dentry(struct dentry *dentry, struct shfl_fsobjinfo *info)
 
 int vboxsf_inode_revalidate(struct dentry *dentry)
 {
-       struct vboxsf_sbi *sbi = VBOXSF_SBI(dentry->d_sb);
+       struct vboxsf_sbi *sbi;
        struct vboxsf_inode *sf_i;
        struct shfl_fsobjinfo info;
        struct timespec64 prev_mtime;
@@ -187,6 +187,7 @@ int vboxsf_inode_revalidate(struct dentry *dentry)
        inode = d_inode(dentry);
        prev_mtime = inode->i_mtime;
        sf_i = VBOXSF_I(inode);
+       sbi = VBOXSF_SBI(dentry->d_sb);
        if (!sf_i->force_restat) {
                if (time_before(jiffies, dentry->d_time + sbi->o.ttl))
                        return 0;