diff options
author | Oleg Nesterov <oleg@redhat.com> | 2010-04-23 13:18:01 -0400 |
---|---|---|
committer | Linus Torvalds <torvalds@linux-foundation.org> | 2010-04-24 14:31:25 -0400 |
commit | 31f2b0ebc01fd332cb0997f7ce9f9cde29af9e20 (patch) | |
tree | fc9d4cb410052afcc56bb8442a2dbcb8950464a8 /mm/rmap.c | |
parent | 93b4a44f3ad69520d605aace3f3486b8eb754b96 (diff) |
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>
Reviewed-by: Rik van Riel <riel@redhat.com>
Cc: Hugh Dickins <hugh.dickins@tiscali.co.uk>
Cc: Pete Zaitcev <zaitcev@redhat.com>
Cc: Borislav Petkov <bp@alien8.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm/rmap.c')
-rw-r--r-- | mm/rmap.c | 9 |
1 files changed, 5 insertions, 4 deletions
@@ -133,8 +133,8 @@ int anon_vma_prepare(struct vm_area_struct *vma) | |||
133 | goto out_enomem_free_avc; | 133 | goto out_enomem_free_avc; |
134 | allocated = anon_vma; | 134 | allocated = anon_vma; |
135 | } | 135 | } |
136 | spin_lock(&anon_vma->lock); | ||
137 | 136 | ||
137 | spin_lock(&anon_vma->lock); | ||
138 | /* page_table_lock to protect against threads */ | 138 | /* page_table_lock to protect against threads */ |
139 | spin_lock(&mm->page_table_lock); | 139 | spin_lock(&mm->page_table_lock); |
140 | if (likely(!vma->anon_vma)) { | 140 | if (likely(!vma->anon_vma)) { |
@@ -144,14 +144,15 @@ int anon_vma_prepare(struct vm_area_struct *vma) | |||
144 | list_add(&avc->same_vma, &vma->anon_vma_chain); | 144 | list_add(&avc->same_vma, &vma->anon_vma_chain); |
145 | list_add(&avc->same_anon_vma, &anon_vma->head); | 145 | list_add(&avc->same_anon_vma, &anon_vma->head); |
146 | allocated = NULL; | 146 | allocated = NULL; |
147 | avc = NULL; | ||
147 | } | 148 | } |
148 | spin_unlock(&mm->page_table_lock); | 149 | spin_unlock(&mm->page_table_lock); |
149 | |||
150 | spin_unlock(&anon_vma->lock); | 150 | spin_unlock(&anon_vma->lock); |
151 | if (unlikely(allocated)) { | 151 | |
152 | if (unlikely(allocated)) | ||
152 | anon_vma_free(allocated); | 153 | anon_vma_free(allocated); |
154 | if (unlikely(avc)) | ||
153 | anon_vma_chain_free(avc); | 155 | anon_vma_chain_free(avc); |
154 | } | ||
155 | } | 156 | } |
156 | return 0; | 157 | return 0; |
157 | 158 | ||