3.10-stable review patch. If anyone has any objections, please let me know.
------------------ From: Rik van Riel <[email protected]> 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 <[email protected]> Reported-by: Dmitry Vyukov <[email protected]> Cc: PaX Team <[email protected]> Cc: Kees Cook <[email protected]> Cc: Michel Lespinasse <[email protected]> Cc: Cyrill Gorcunov <[email protected]> Cc: Hugh Dickins <[email protected]> Signed-off-by: Andrew Morton <[email protected]> Signed-off-by: Linus Torvalds <[email protected]> Signed-off-by: Greg Kroah-Hartman <[email protected]> --- mm/fremap.c | 8 +++++--- 1 file changed, 5 insertions(+), 3 deletions(-) --- a/mm/fremap.c +++ b/mm/fremap.c @@ -203,9 +203,10 @@ 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; @@ -213,7 +214,7 @@ 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); @@ -248,6 +249,7 @@ get_write_lock: out: if (vma) vm_flags = vma->vm_flags; +out_freed: if (likely(!has_write_lock)) up_read(&mm->mmap_sem); else -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
