[Devel] [PATCH RH7 3/4] __dentry_path() fixes

[Pavel Tikhomirov]

From: Al Viro <viro at zeniv.linux.org.uk>

Port mainstream commit:

  commit f6500801522c61782d4990fa1ad96154cb397cd4
  Author: Al Viro <viro at zeniv.linux.org.uk>
  Date:   Sun Jan 26 12:37:55 2014 -0500

      __dentry_path() fixes

      * we need to save the starting point for restarts
      * reject pathologically short buffers outright

      Spotted-by: Denys Vlasenko <dvlasenk at redhat.com>
      Spotted-by: Oleg Nesterov <oleg at redhat.com>
      Signed-off-by: Al Viro <viro at zeniv.linux.org.uk>

https://jira.sw.ru/browse/PSBM-34245
Signed-off-by: Pavel Tikhomirov <ptikhomirov at virtuozzo.com>
---
 fs/dcache.c | 9 ++++++---
 1 file changed, 6 insertions(+), 3 deletions(-)

diff --git a/fs/dcache.c b/fs/dcache.c
index ecbfb07..ad4acc4 100644
--- a/fs/dcache.c
+++ b/fs/dcache.c
@@ -3099,19 +3099,22 @@ char *simple_dname(struct dentry *dentry, char *buffer, int buflen)
 /*
  * Write full pathname from the root of the filesystem into the buffer.
  */
-static char *__dentry_path(struct dentry *dentry, char *buf, int buflen)
+static char *__dentry_path(struct dentry *d, char *buf, int buflen)
 {
+	struct dentry *dentry;
 	char *end, *retval;
 	int len, seq = 0;
 	int error = 0;
 
+	if (buflen < 2)
+		goto Elong;
+
 	rcu_read_lock();
 restart:
+	dentry = d;
 	end = buf + buflen;
 	len = buflen;
 	prepend(&end, &len, "\0", 1);
-	if (buflen < 1)
-		goto Elong;
 	/* Get '/' right */
 	retval = end-1;
 	*retval = '/';
-- 
1.9.3