From: Matt Mackall <mpm@selenic.com>
Date: Tue, 7 Oct 2008 16:37:35 +0000 (-0500)
Subject: SLOB: fix bogus ksize calculation
X-Git-Tag: v2.6.27~7
X-Git-Url: http://www.pilppa.org/gitweb/gitweb.cgi?p=linux-2.6-omap-h63xx.git;a=commitdiff_plain;h=85ba94ba0592296053f7f2846812173424afe1cb

SLOB: fix bogus ksize calculation

SLOB's ksize calculation was braindamaged and generally harmlessly
underreported the allocation size. But for very small buffers, it could
in fact overreport them, leading code depending on krealloc to overrun
the allocation and trample other data.

Signed-off-by: Matt Mackall <mpm@selenic.com>
Tested-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
---

diff --git a/mm/slob.c b/mm/slob.c
index 4c82dd41f32..62b679dc660 100644
--- a/mm/slob.c
+++ b/mm/slob.c
@@ -515,7 +515,7 @@ size_t ksize(const void *block)
 
 	sp = (struct slob_page *)virt_to_page(block);
 	if (slob_page(sp))
-		return ((slob_t *)block - 1)->units + SLOB_UNIT;
+		return (((slob_t *)block - 1)->units - 1) * SLOB_UNIT;
 	else
 		return sp->page.private;
 }