lindebugfs: Make single_release() NULL safe.

Sponsored by:	NVIDIA Networking
Approved by:	re (gjb)

(cherry picked from commit a23e475c48da7a3751ffdc689be01d514ea2857c)
(cherry picked from commit d67b2c96153fcef344648d907893b50e30817a38)

diff --git a/sys/compat/linuxkpi/common/src/linux_seq_file.c b/sys/compat/linuxkpi/common/src/linux_seq_file.c
index 6f4f1a368c4a90d11fe6e731540b9753bc192b1e..ed23bf8d010f46395f9b10f7f7e89952c9a11b9a 100644 (file)
--- a/sys/compat/linuxkpi/common/src/linux_seq_file.c
+++ b/sys/compat/linuxkpi/common/src/linux_seq_file.c
@@ -147,9 +147,15 @@ seq_release(struct inode *inode __unused, struct linux_file *file)
 int
 single_release(struct vnode *v, struct linux_file *f)
 {
-       const struct seq_operations *op = ((struct seq_file *)f->private_data)->op;
+       const struct seq_operations *op;
+       struct seq_file *m;
        int rc;
 
+       /* be NULL safe */
+       if ((m = f->private_data) == NULL)
+               return (0);
+
+       op = m->op;
        rc = seq_release(v, f);
        free(__DECONST(void *, op), M_LSEQ);
        return (rc);