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Message-Id: <cdc026315954a8d1fda21de1b21edfad39cbef5c.1420799385.git.jslaby@suse.cz>
Date: Fri, 9 Jan 2015 11:31:28 +0100
From: Jiri Slaby <jslaby@...e.cz>
To: stable@...r.kernel.org
Cc: linux-kernel@...r.kernel.org,
Daniel Forrest <dan.forrest@...c.wisc.edu>,
Konstantin Khlebnikov <koct9i@...il.com>,
Andrea Arcangeli <aarcange@...hat.com>,
Rik van Riel <riel@...hat.com>,
Tim Hartrick <tim@...ecast.com>,
Hugh Dickins <hughd@...gle.com>,
Michel Lespinasse <walken@...gle.com>,
Vlastimil Babka <vbabka@...e.cz>,
Andrew Morton <akpm@...ux-foundation.org>,
Linus Torvalds <torvalds@...ux-foundation.org>,
Jiri Slaby <jslaby@...e.cz>
Subject: [PATCH 3.12 19/78] mm: fix anon_vma_clone() error treatment
From: Daniel Forrest <dan.forrest@...c.wisc.edu>
3.12-stable review patch. If anyone has any objections, please let me know.
===============
commit c4ea95d7cd08d9ffd7fa75e6c5e0332d596dd11e upstream.
Andrew Morton noticed that the error return from anon_vma_clone() was
being dropped and replaced with -ENOMEM (which is not itself a bug
because the only error return value from anon_vma_clone() is -ENOMEM).
I did an audit of callers of anon_vma_clone() and discovered an actual
bug where the error return was being lost. In __split_vma(), between
Linux 3.11 and 3.12 the code was changed so the err variable is used
before the call to anon_vma_clone() and the default initial value of
-ENOMEM is overwritten. So a failure of anon_vma_clone() will return
success since err at this point is now zero.
Below is a patch which fixes this bug and also propagates the error
return value from anon_vma_clone() in all cases.
Fixes: ef0855d334e1 ("mm: mempolicy: turn vma_set_policy() into vma_dup_policy()")
Signed-off-by: Daniel Forrest <dan.forrest@...c.wisc.edu>
Reviewed-by: Michal Hocko <mhocko@...e.cz>
Cc: Konstantin Khlebnikov <koct9i@...il.com>
Cc: Andrea Arcangeli <aarcange@...hat.com>
Cc: Rik van Riel <riel@...hat.com>
Cc: Tim Hartrick <tim@...ecast.com>
Cc: Hugh Dickins <hughd@...gle.com>
Cc: Michel Lespinasse <walken@...gle.com>
Cc: Vlastimil Babka <vbabka@...e.cz>
Signed-off-by: Andrew Morton <akpm@...ux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@...ux-foundation.org>
Signed-off-by: Jiri Slaby <jslaby@...e.cz>
---
mm/mmap.c | 10 +++++++---
mm/rmap.c | 6 ++++--
2 files changed, 11 insertions(+), 5 deletions(-)
diff --git a/mm/mmap.c b/mm/mmap.c
index c1249cb7dc15..15e07d5a75cb 100644
--- a/mm/mmap.c
+++ b/mm/mmap.c
@@ -746,8 +746,11 @@ again: remove_next = 1 + (end > next->vm_end);
* shrinking vma had, to cover any anon pages imported.
*/
if (exporter && exporter->anon_vma && !importer->anon_vma) {
- if (anon_vma_clone(importer, exporter))
- return -ENOMEM;
+ int error;
+
+ error = anon_vma_clone(importer, exporter);
+ if (error)
+ return error;
importer->anon_vma = exporter->anon_vma;
}
}
@@ -2419,7 +2422,8 @@ static int __split_vma(struct mm_struct * mm, struct vm_area_struct * vma,
if (err)
goto out_free_vma;
- if (anon_vma_clone(new, vma))
+ err = anon_vma_clone(new, vma);
+ if (err)
goto out_free_mpol;
if (new->vm_file)
diff --git a/mm/rmap.c b/mm/rmap.c
index 4271107aa46e..5b8675ccc1ef 100644
--- a/mm/rmap.c
+++ b/mm/rmap.c
@@ -274,6 +274,7 @@ int anon_vma_fork(struct vm_area_struct *vma, struct vm_area_struct *pvma)
{
struct anon_vma_chain *avc;
struct anon_vma *anon_vma;
+ int error;
/* Don't bother if the parent process has no anon_vma here. */
if (!pvma->anon_vma)
@@ -283,8 +284,9 @@ int anon_vma_fork(struct vm_area_struct *vma, struct vm_area_struct *pvma)
* First, attach the new VMA to the parent VMA's anon_vmas,
* so rmap can find non-COWed pages in child processes.
*/
- if (anon_vma_clone(vma, pvma))
- return -ENOMEM;
+ error = anon_vma_clone(vma, pvma);
+ if (error)
+ return error;
/* Then add our own anon_vma. */
anon_vma = anon_vma_alloc();
--
2.2.1
--
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