Eric Lee / smarc-ti-linux-kernel

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Commit c4ea95d7cd08d9ffd7fa75e6c5e0332d596dd11e

Authored by Daniel Forrest
Committed by Linus Torvalds
1 parent 2022b4d18a
Exists in ti-lsk-linux-4.1.y and in 10 other branches dlt-processor-sdk-linux-03.00.00.04, processor-sdk-linux-02.00.01, smarc-ti-lsk-linux-4.1.y, smarct3x-processor-sdk-04.01.00.06, smarct3x-processor-sdk-linux-02.00.01, smarct3x-processor-sdk-linux-03.00.00.04, smarct4x-800-processor-sdk-linux-02.00.01, smarct4x-processor-sdk-04.01.00.06, smarct4x-processor-sdk-linux-02.00.01, smarct4x-processor-sdk-linux-03.00.00.04

mm: fix anon_vma_clone() error treatment 

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@ssec.wisc.edu>
Reviewed-by: Michal Hocko <mhocko@suse.cz>
Cc: Konstantin Khlebnikov <koct9i@gmail.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: Tim Hartrick <tim@edgecast.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Michel Lespinasse <walken@google.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: <stable@vger.kernel.org>	[3.12+]
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Showing 2 changed files with 11 additions and 5 deletions Side-by-side Diff

... ... @@ -776,8 +776,11 @@
776 776 * shrinking vma had, to cover any anon pages imported.
777 777 */
778 778 if (exporter && exporter->anon_vma && !importer->anon_vma) {
779   - if (anon_vma_clone(importer, exporter))
780   - return -ENOMEM;
  779 + int error;
  780 +
  781 + error = anon_vma_clone(importer, exporter);
  782 + if (error)
  783 + return error;
781 784 importer->anon_vma = exporter->anon_vma;
782 785 }
783 786 }
... ... @@ -2469,7 +2472,8 @@
2469 2472 if (err)
2470 2473 goto out_free_vma;
2471 2474  
2472   - if (anon_vma_clone(new, vma))
  2475 + err = anon_vma_clone(new, vma);
  2476 + if (err)
2473 2477 goto out_free_mpol;
2474 2478  
2475 2479 if (new->vm_file)
... ... @@ -274,6 +274,7 @@
274 274 {
275 275 struct anon_vma_chain *avc;
276 276 struct anon_vma *anon_vma;
  277 + int error;
277 278  
278 279 /* Don't bother if the parent process has no anon_vma here. */
279 280 if (!pvma->anon_vma)
... ... @@ -283,8 +284,9 @@
283 284 * First, attach the new VMA to the parent VMA's anon_vmas,
284 285 * so rmap can find non-COWed pages in child processes.
285 286 */
286   - if (anon_vma_clone(vma, pvma))
287   - return -ENOMEM;
  287 + error = anon_vma_clone(vma, pvma);
  288 + if (error)
  289 + return error;
288 290  
289 291 /* Then add our own anon_vma. */
290 292 anon_vma = anon_vma_alloc();