lkml.org 
[lkml]   [2016]   [Jun]   [6]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
From
Subject[PATCH] mm/page_owner: avoid null pointer dereference
Date
We have dereferenced page_ext before checking it. Lets check it first
and then used it.

Signed-off-by: Sudip Mukherjee <sudip.mukherjee@codethink.co.uk>
---
mm/page_owner.c | 6 ++++--
1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/mm/page_owner.c b/mm/page_owner.c
index 587dcca..8fa5083 100644
--- a/mm/page_owner.c
+++ b/mm/page_owner.c
@@ -291,13 +291,15 @@ void __dump_page_owner(struct page *page)
.skip = 0
};
depot_stack_handle_t handle;
- gfp_t gfp_mask = page_ext->gfp_mask;
- int mt = gfpflags_to_migratetype(gfp_mask);
+ gfp_t gfp_mask;
+ int mt;

if (unlikely(!page_ext)) {
pr_alert("There is not page extension available.\n");
return;
}
+ gfp_mask = page_ext->gfp_mask;
+ mt = gfpflags_to_migratetype(gfp_mask);

if (!test_bit(PAGE_EXT_OWNER, &page_ext->flags)) {
pr_alert("page_owner info is not active (free page?)\n");
--
1.9.1
\
 
 \ /
  Last update: 2016-06-07 00:01    [W:0.035 / U:0.036 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site