Messages in this thread Patch in this message | | | Date | Fri, 9 Aug 2013 13:16:41 +0800 | Subject | [PATCH 1/1] pagemap: fix buffer overflow in add_page_map() | From | yonghua zheng <> |
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Hi,
Recently we met quite a lot of random kernel panic issues after enable CONFIG_PROC_PAGE_MONITOR in kernel, after debuggint sometime we found this has something to do with following bug in pagemap:
In struc 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@gmail.com> --- fs/proc/task_mmu.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c index dbf61f6..cb98853 100644 --- a/fs/proc/task_mmu.c +++ b/fs/proc/task_mmu.c @@ -1116,8 +1116,8 @@ static ssize_t pagemap_read(struct file *file, char __user *buf, 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; -- 1.7.9.5
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