From aa91c4d898c062804f4d0a5da6d8ab013cd0e868 Mon Sep 17 00:00:00 2001
From: Jan Kara <jack@suse.cz>
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 <jack@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
---
mm/vmalloc.c | 8 ++++++++
1 file changed, 8 insertions(+)
diff --git a/mm/vmalloc.c b/mm/vmalloc.c
index 7e25ee3ce6e54..2bb90b1d241cc 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:
--
2.30.2