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.
Reported-by: Hector Marco-Gisbert <hecmargi@xxxxxx>
Signed-off-by: Kees Cook <keescook@xxxxxxxxxxxx>
---
mm/mmap.c | 8 +++++---
1 file changed, 5 insertions(+), 3 deletions(-)
diff --git a/mm/mmap.c b/mm/mmap.c
index de2c1769cc68..1874ee0e1266 100644
--- a/mm/mmap.c
+++ b/mm/mmap.c
@@ -2625,16 +2625,18 @@ 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 int do_brk(unsigned long addr, unsigned long len)
+static int 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 0;
--
2.7.4
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