From bcb615a81b1765864c71c50afb56631e7a1e5283 Mon Sep 17 00:00:00 2001 From: Zhang Yanfei Date: Mon, 8 Jul 2013 16:00:19 -0700 Subject: [PATCH] mm/vmalloc.c: fix an overflow bug in alloc_vmap_area() When searching a vmap area in the vmalloc space, we use (addr + size - 1) to check if the value is less than addr, which is an overflow. But we assign (addr + size) to vmap_area->va_end. So if we come across the below case: (addr + size - 1) : not overflow (addr + size) : overflow we will assign an overflow value (e.g 0) to vmap_area->va_end, And this will trigger BUG in __insert_vmap_area, causing system panic. So using (addr + size) to check the overflow should be the correct behaviour, not (addr + size - 1). Signed-off-by: Zhang Yanfei Reported-by: Ghennadi Procopciuc Tested-by: Daniel Baluta Cc: David Rientjes Cc: Minchan Kim Cc: KOSAKI Motohiro Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- mm/vmalloc.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) diff --git a/mm/vmalloc.c b/mm/vmalloc.c index a649186669a3..13a54953a273 100644 --- a/mm/vmalloc.c +++ b/mm/vmalloc.c @@ -388,12 +388,12 @@ nocache: addr = ALIGN(first->va_end, align); if (addr < vstart) goto nocache; - if (addr + size - 1 < addr) + if (addr + size < addr) goto overflow; } else { addr = ALIGN(vstart, align); - if (addr + size - 1 < addr) + if (addr + size < addr) goto overflow; n = vmap_area_root.rb_node; @@ -420,7 +420,7 @@ nocache: if (addr + cached_hole_size < first->va_start) cached_hole_size = first->va_start - addr; addr = ALIGN(first->va_end, align); - if (addr + size - 1 < addr) + if (addr + size < addr) goto overflow; if (list_is_last(&first->list, &vmap_area_list)) -- 2.20.1