4.4-stable review patch. If anyone has any objections, please let me know.
------------------ commit ba093a6d9397da8eafcfbaa7d95bd34255da39a0 upstream. The vm_brk() alignment calculations should refuse to overflow. The ELF loader depending on this, but it has been fixed now. No other unsafe callers have been found. Link: http://lkml.kernel.org/r/[email protected] Signed-off-by: Kees Cook <[email protected]> Reported-by: Hector Marco-Gisbert <[email protected]> Cc: Ismael Ripoll Ripoll <[email protected]> Cc: Alexander Viro <[email protected]> Cc: "Kirill A. Shutemov" <[email protected]> Cc: Oleg Nesterov <[email protected]> Cc: Chen Gang <[email protected]> Cc: Michal Hocko <[email protected]> Cc: Konstantin Khlebnikov <[email protected]> Cc: Andrea Arcangeli <[email protected]> Cc: Andrey Ryabinin <[email protected]> Signed-off-by: Andrew Morton <[email protected]> Signed-off-by: Linus Torvalds <[email protected]> [bwh: Backported to 4.4: adjust context] Signed-off-by: Ben Hutchings <[email protected]> Signed-off-by: Sasha Levin <[email protected]> --- mm/mmap.c | 8 +++++--- 1 file changed, 5 insertions(+), 3 deletions(-) diff --git a/mm/mmap.c b/mm/mmap.c index 39f5fbd07486..dd9205542a86 100644 --- a/mm/mmap.c +++ b/mm/mmap.c @@ -2808,16 +2808,18 @@ static inline void verify_mm_writelocked(struct mm_struct *mm) * anonymous maps. eventually we may be able to do some * brk-specific accounting here. */ -static unsigned long do_brk(unsigned long addr, unsigned long len) +static unsigned long do_brk(unsigned long addr, unsigned long request) { struct mm_struct *mm = current->mm; struct vm_area_struct *vma, *prev; - unsigned long flags; + unsigned long flags, len; struct rb_node **rb_link, *rb_parent; pgoff_t pgoff = addr >> PAGE_SHIFT; int error; - len = PAGE_ALIGN(len); + len = PAGE_ALIGN(request); + if (len < request) + return -ENOMEM; if (!len) return addr; -- 2.17.1
