From mboxrd@z Thu Jan 1 00:00:00 1970 Return-path: Received: from jacques.telenet-ops.be ([195.130.132.50]) by merlin.infradead.org with esmtp (Exim 4.80.1 #2 (Red Hat Linux)) id 1VO1M0-0006zZ-DJ for kexec@lists.infradead.org; Mon, 23 Sep 2013 08:18:49 +0000 From: Geert Uytterhoeven Subject: [PATCH] [RFC] kexec: Fix off-by-one errors in locate_hole() Date: Mon, 23 Sep 2013 10:18:12 +0200 Message-Id: <1379924292-1712-1-git-send-email-geert@linux-m68k.org> List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "kexec" Errors-To: kexec-bounces+dwmw2=twosheds.infradead.org@lists.infradead.org To: Simon Horman Cc: Geert Uytterhoeven , kexec@lists.infradead.org When calling locate_hole() with "hole_size" equal to the size of an available memory block, it fails to use that memory block. "end" and "hole_max" point to the last byte within the range, hence - "size = end - start" is one less than "hole_size", - "hole_base + hole_size" is one more than "hole_max". Subtract one from "hole_size" when doing the comparison (adding 1 to "size" could overflow in case of one big range covering the whole address space). Signed-off-by: Geert Uytterhoeven --- Question: The code no longer handles the case where "hole_size" is zero. Should this be rejected (like is done for a zero "hole_end" at the top of the function), or accepted? kexec/kexec.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/kexec/kexec.c b/kexec/kexec.c index 2b98ef0..eafd6c2 100644 --- a/kexec/kexec.c +++ b/kexec/kexec.c @@ -270,7 +270,7 @@ unsigned long locate_hole(struct kexec_info *info, } /* Is there enough space left so we can use it? */ size = end - start; - if (size >= hole_size) { + if (size >= hole_size - 1) { if (hole_end > 0) { hole_base = start; break; @@ -286,7 +286,7 @@ unsigned long locate_hole(struct kexec_info *info, "0x%lx bytes...\n", hole_size); return ULONG_MAX; } - if ((hole_base + hole_size) > hole_max) { + if ((hole_base + hole_size - 1) > hole_max) { fprintf(stderr, "Could not find a free area of memory below: " "0x%lx...\n", hole_max); return ULONG_MAX; -- 1.7.9.5 _______________________________________________ kexec mailing list kexec@lists.infradead.org http://lists.infradead.org/mailman/listinfo/kexec