[lkml]   [2013]   [Nov]   [18]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
Messages in this thread
Patch in this message
Subject[PATCH] FS: Fixed buffer overflow issue in seq_read()
The buffer count is not initialized when a new buffer is allocated. 

It cause kernel crash with "Unable to handle kernel paging
request..." error in __copy_to_user_std(). It happens when a
memory allocation failure in the while(1)-loop, which left the
buffer count (m->count) is larger than buffer size

This patch is currently against a linux 3.12 kernel

Signed-off-by: Charley Chu
diff --git a/fs/seq_file.c b/fs/seq_file.c
index 1cd2388..480a341 100644
--- a/fs/seq_file.c
+++ b/fs/seq_file.c
@@ -191,6 +191,7 @@ ssize_t seq_read(struct file *file, char __user *buf, size_t size, loff_t *ppos)

/* grab buffer if we didn't have one */
if (!m->buf) {
+ m->count = m->from = 0;
m->buf = kmalloc(m->size = PAGE_SIZE, GFP_KERNEL);
if (!m->buf)
goto Enomem;

 \ /
  Last update: 2013-11-19 01:41    [W:0.066 / U:9.968 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site