lkml.org 
[lkml]   [2010]   [Apr]   [20]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
Date
From
Subject[PATCH] rmap: anon_vma_prepare() can leak anon_vma_chain
If find_mergeable_anon_vma() succeeds but another thread installs
->anon_vma before we take ptl, then allocated == NULL but avc should
be freed. Change the code to check avc != NULL to detect this case.

Also, a couple of whitespace changes to make the critical section more
visible.

Signed-off-by: Oleg Nesterov <oleg@redhat.com>
---

mm/rmap.c | 9 +++++----
1 file changed, 5 insertions(+), 4 deletions(-)

--- 34-rc1/mm/rmap.c~AVP_AVC_LEAK 2010-03-11 13:11:50.000000000 +0100
+++ 34-rc1/mm/rmap.c 2010-04-20 21:05:24.000000000 +0200
@@ -133,8 +133,8 @@ int anon_vma_prepare(struct vm_area_stru
goto out_enomem_free_avc;
allocated = anon_vma;
}
- spin_lock(&anon_vma->lock);

+ spin_lock(&anon_vma->lock);
/* page_table_lock to protect against threads */
spin_lock(&mm->page_table_lock);
if (likely(!vma->anon_vma)) {
@@ -144,14 +144,15 @@ int anon_vma_prepare(struct vm_area_stru
list_add(&avc->same_vma, &vma->anon_vma_chain);
list_add(&avc->same_anon_vma, &anon_vma->head);
allocated = NULL;
+ avc = NULL;
}
spin_unlock(&mm->page_table_lock);
-
spin_unlock(&anon_vma->lock);
- if (unlikely(allocated)) {
+
+ if (unlikely(allocated))
anon_vma_free(allocated);
+ if (unlikely(avc))
anon_vma_chain_free(avc);
- }
}
return 0;



\
 
 \ /
  Last update: 2010-04-20 21:29    [W:0.047 / U:0.860 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site