Subject: + pagemap-fix-buffer-overflow-in-add_page_map.patch added to -mm tree
To: younghua.zheng@xxxxxxxxx
From: akpm@xxxxxxxxxxxxxxxxxxxx
Date: Mon, 12 Aug 2013 16:05:45 -0700
The patch titled
Subject: fs/proc/task_mmu.c: fix buffer overflow in add_page_map()
has been added to the -mm tree. Its filename is
pagemap-fix-buffer-overflow-in-add_page_map.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/pagemap-fix-buffer-overflow-in-add_page_map.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/pagemap-fix-buffer-overflow-in-add_page_map.patch
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From: yonghua zheng <younghua.zheng@xxxxxxxxx>
Subject: fs/proc/task_mmu.c: fix buffer overflow in add_page_map()
Recently we met quite a lot of random kernel panic issues after enabling
CONFIG_PROC_PAGE_MONITOR. After debuggind we found this has something to
do with following bug in pagemap:
In struct pagemapread:
struct pagemapread {
int pos, len;
pagemap_entry_t *buffer;
bool v2;
};
pos is number of PM_ENTRY_BYTES in buffer, but len is the size of buffer,
it is a mistake to compare pos and len in add_page_map() for checking
buffer is full or not, and this can lead to buffer overflow and random
kernel panic issue.
Correct len to be total number of PM_ENTRY_BYTES in buffer.
Signed-off-by: Yonghua Zheng <younghua.zheng@xxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
fs/proc/task_mmu.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff -puN fs/proc/task_mmu.c~pagemap-fix-buffer-overflow-in-add_page_map fs/proc/task_mmu.c
--- a/fs/proc/task_mmu.c~pagemap-fix-buffer-overflow-in-add_page_map
+++ a/fs/proc/task_mmu.c
@@ -1127,8 +1127,8 @@ static ssize_t pagemap_read(struct file
goto out_task;
pm.v2 = soft_dirty_cleared;
- pm.len = PM_ENTRY_BYTES * (PAGEMAP_WALK_SIZE >> PAGE_SHIFT);
- pm.buffer = kmalloc(pm.len, GFP_TEMPORARY);
+ pm.len = (PAGEMAP_WALK_SIZE >> PAGE_SHIFT);
+ pm.buffer = kmalloc(pm.len * PM_ENTRY_BYTES, GFP_TEMPORARY);
ret = -ENOMEM;
if (!pm.buffer)
goto out_task;
_
Patches currently in -mm which might be from younghua.zheng@xxxxxxxxx are
pagemap-fix-buffer-overflow-in-add_page_map.patch
pagemap-fix-buffer-overflow-in-add_page_map-fix.patch
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