linux-kernel - [PATCH] SeqFile: Fix overflow condition

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Message-ID: <CAKZGPAOwpEcxxZJUbmUVL1J+enXGhFbbvyZ7L3uWDkPbwKnbyQ@mail.gmail.com>
Date:	Mon, 19 Aug 2013 17:02:37 +0530
From:	Arun KS <arunks.linux@...il.com>
To:	viro@...iv.linux.org.uk, Andrew Morton <akpm@...ux-foundation.org>
Cc:	Matthew Wilcox <matthew@....cx>,
	Bruce Fields <bfields@...ldses.org>,
	linux-kernel@...r.kernel.org, linux-fsdevel@...r.kernel.org,
	vinayak menon <vinayakm.list@...il.com>,
	Nagachandra P <nagachandra@...il.com>,
	Vikram MP <mp.vikram@...il.com>
Subject: [PATCH] SeqFile: Fix overflow condition

>From 27f50827e5e81f2a30544b72c1d54c3ee86835cf Mon Sep 17 00:00:00 2001
From: Arun KS <arun.ks@...adcom.com>
Date: Mon, 19 Aug 2013 12:06:33 +0530
Subject: SeqFile: Fix overflow condition

seq_path()/seq_commit() is treating a d_path() failure as an overflow
condition, but it isn't.

Signed-off-by: Arun KS <arun.ks@...adcom.com>
---
 fs/seq_file.c            |    6 +++---
 include/linux/seq_file.h |   12 +++++++-----
 2 files changed, 10 insertions(+), 8 deletions(-)

diff --git a/fs/seq_file.c b/fs/seq_file.c
index 3135c25..6a33f9c 100644
--- a/fs/seq_file.c
+++ b/fs/seq_file.c
@@ -463,7 +463,7 @@ int seq_path(struct seq_file *m, const struct path
*path, const char *esc)
 {
  char *buf;
  size_t size = seq_get_buf(m, &buf);
- int res = -1;
+ int res = -ENOBUFS;

  if (size) {
  char *p = d_path(path, buf, size);
@@ -487,7 +487,7 @@ int seq_path_root(struct seq_file *m, const struct
path *path,
 {
  char *buf;
  size_t size = seq_get_buf(m, &buf);
- int res = -ENAMETOOLONG;
+ int res = -ENOBUFS;

  if (size) {
  char *p;
@@ -516,7 +516,7 @@ int seq_dentry(struct seq_file *m, struct dentry
*dentry, const char *esc)
 {
  char *buf;
  size_t size = seq_get_buf(m, &buf);
- int res = -1;
+ int res = -ENOBUFS;

  if (size) {
  char *p = dentry_path(dentry, buf, size);
diff --git a/include/linux/seq_file.h b/include/linux/seq_file.h
index 4e32edc..43f51a0 100644
--- a/include/linux/seq_file.h
+++ b/include/linux/seq_file.h
@@ -7,6 +7,7 @@
 #include <linux/mutex.h>
 #include <linux/cpumask.h>
 #include <linux/nodemask.h>
+#include <linux/errno.h>

 struct seq_operations;
 struct file;
@@ -66,16 +67,17 @@ static inline size_t seq_get_buf(struct seq_file
*m, char **bufp)
  * @num: the number of bytes to commit
  *
  * Commit @num bytes of data written to a buffer previously acquired
- * by seq_buf_get.  To signal an error condition, or that the data
- * didn't fit in the available space, pass a negative @num value.
+ * by seq_buf_get.  To signal an overflow condition(data didn't fit
+ * in the available space), pass -ENOBUFS and for other errors pass a
+ * negative @num value.
  */
 static inline void seq_commit(struct seq_file *m, int num)
 {
- if (num < 0) {
- m->count = m->size;
- } else {
+ if (num >= 0) {
  BUG_ON(m->count + num > m->size);
  m->count += num;
+ } else if (num == -ENOBUFS)
+ m->count = m->size;
  }
 }

-- 
1.7.6

Download attachment "0001-SeqFile-Fix-overflow-condition.patch" of type "application/octet-stream" (2377 bytes)