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| author | Rik van Riel <riel@redhat.com> | 2014-01-02 12:58:46 -0800 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2014-01-09 12:25:14 -0800 |
| commit | e910af66dc0622a331bd0d2ec0f500005339f44c (patch) | |
| tree | 85d677b2ee747e2ca3c2a96681c0668d3e633cc9 /mm | |
| parent | 1f8653248dee285e931c38340a351b36c1e93de4 (diff) | |
| download | lwn-e910af66dc0622a331bd0d2ec0f500005339f44c.tar.gz lwn-e910af66dc0622a331bd0d2ec0f500005339f44c.zip | |
mm: fix use-after-free in sys_remap_file_pages
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@redhat.com>
Reported-by: Dmitry Vyukov <dvyukov@google.com>
Cc: PaX Team <pageexec@freemail.hu>
Cc: Kees Cook <keescook@chromium.org>
Cc: Michel Lespinasse <walken@google.com>
Cc: Cyrill Gorcunov <gorcunov@openvz.org>
Cc: Hugh Dickins <hughd@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'mm')
| -rw-r--r-- | mm/fremap.c | 8 |
1 files changed, 5 insertions, 3 deletions
diff --git a/mm/fremap.c b/mm/fremap.c index 5bff08147768..bbc4d660221a 100644 --- 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 |