This is a note to let you know that I've just added the patch titled
mm: fix use-after-free in sys_remap_file_pages
to the 3.12-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
mm-fix-use-after-free-in-sys_remap_file_pages.patch
and it can be found in the queue-3.12 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From 4eb919825e6c3c7fb3630d5621f6d11e98a18b3a Mon Sep 17 00:00:00 2001
From: Rik van Riel <riel@xxxxxxxxxx>
Date: Thu, 2 Jan 2014 12:58:46 -0800
Subject: mm: fix use-after-free in sys_remap_file_pages
From: Rik van Riel <riel@xxxxxxxxxx>
commit 4eb919825e6c3c7fb3630d5621f6d11e98a18b3a upstream.
remap_file_pages calls mmap_region, which may merge the VMA with other
existing VMAs, and free "vma". This can lead to a use-after-free bug.
Avoid the bug by remembering vm_flags before calling mmap_region, and
not trying to dereference vma later.
Signed-off-by: Rik van Riel <riel@xxxxxxxxxx>
Reported-by: Dmitry Vyukov <dvyukov@xxxxxxxxxx>
Cc: PaX Team <pageexec@xxxxxxxxxxx>
Cc: Kees Cook <keescook@xxxxxxxxxxxx>
Cc: Michel Lespinasse <walken@xxxxxxxxxx>
Cc: Cyrill Gorcunov <gorcunov@xxxxxxxxxx>
Cc: Hugh Dickins <hughd@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
mm/fremap.c | 8 +++++---
1 file changed, 5 insertions(+), 3 deletions(-)
--- a/mm/fremap.c
+++ b/mm/fremap.c
@@ -208,9 +208,10 @@ get_write_lock:
if (mapping_cap_account_dirty(mapping)) {
unsigned long addr;
struct file *file = get_file(vma->vm_file);
+ /* mmap_region may free vma; grab the info now */
+ vm_flags = vma->vm_flags;
- addr = mmap_region(file, start, size,
- vma->vm_flags, pgoff);
+ addr = mmap_region(file, start, size, vm_flags, pgoff);
fput(file);
if (IS_ERR_VALUE(addr)) {
err = addr;
@@ -218,7 +219,7 @@ get_write_lock:
BUG_ON(addr != start);
err = 0;
}
- goto out;
+ goto out_freed;
}
mutex_lock(&mapping->i_mmap_mutex);
flush_dcache_mmap_lock(mapping);
@@ -253,6 +254,7 @@ get_write_lock:
out:
if (vma)
vm_flags = vma->vm_flags;
+out_freed:
if (likely(!has_write_lock))
up_read(&mm->mmap_sem);
else
Patches currently in stable-queue which might be from riel@xxxxxxxxxx are
queue-3.12/sched-numa-skip-inaccessible-vmas.patch
queue-3.12/mm-fix-use-after-free-in-sys_remap_file_pages.patch
queue-3.12/mm-compaction-respect-ignore_skip_hint-in-update_pageblock_skip.patch
queue-3.12/mm-clear-pmd_numa-before-invalidating.patch
queue-3.12/mm-fix-tlb-flush-race-between-migration-and-change_protection_range.patch
queue-3.12/mm-numa-ensure-anon_vma-is-locked-to-prevent-parallel-thp-splits.patch
queue-3.12/mm-munlock-fix-deadlock-in-__munlock_pagevec.patch
queue-3.12/mm-numa-guarantee-that-tlb_flush_pending-updates-are-visible-before-page-table-updates.patch
queue-3.12/mm-numa-avoid-unnecessary-work-on-the-failure-path.patch
queue-3.12/mm-mempolicy-correct-putback-method-for-isolate-pages-if-failed.patch
queue-3.12/mm-munlock-fix-a-bug-where-thp-tail-page-is-encountered.patch
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