From aa91c4d898c062804f4d0a5da6d8ab013cd0e868 Mon Sep 17 00:00:00 2001 From: Jan Kara Date: Tue, 31 Jul 2012 16:41:37 -0700 Subject: [PATCH] mm: make vb_alloc() more foolproof If someone calls vb_alloc() (or vm_map_ram() for that matter) to allocate 0 bytes (0 pages), get_order() returns BITS_PER_LONG - PAGE_CACHE_SHIFT and interesting stuff happens. So make debugging such problems easier and warn about 0-size allocation. [akpm@linux-foundation.org: use WARN_ON-return-value feature] Signed-off-by: Jan Kara Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- mm/vmalloc.c | 8 ++++++++ 1 file changed, 8 insertions(+) diff --git a/mm/vmalloc.c b/mm/vmalloc.c index 7e25ee3ce6e5..2bb90b1d241c 100644 --- a/mm/vmalloc.c +++ b/mm/vmalloc.c @@ -904,6 +904,14 @@ static void *vb_alloc(unsigned long size, gfp_t gfp_mask) BUG_ON(size & ~PAGE_MASK); BUG_ON(size > PAGE_SIZE*VMAP_MAX_ALLOC); + if (WARN_ON(size == 0)) { + /* + * Allocating 0 bytes isn't what caller wants since + * get_order(0) returns funny result. Just warn and terminate + * early. + */ + return NULL; + } order = get_order(size); again: -- 2.34.1