linux-kernel - [PATCH 4/7] FRV: Eliminate NULL test and memset after alloc

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <20081015155104.2158.33413.stgit@warthog.procyon.org.uk>
Date:	Wed, 15 Oct 2008 16:51:04 +0100
From:	David Howells <dhowells@...hat.com>
To:	torvalds@...l.org
Cc:	linux-kernel@...r.kernel.org, Julia Lawall <julia@...u.dk>,
	David Howells <dhowells@...hat.com>
Subject: [PATCH 4/7] FRV: Eliminate NULL test and memset after alloc_bootmem

From: Julia Lawall <julia@...u.dk>

As noted by Akinobu Mita in patch b1fceac2b9e04d278316b2faddf276015fc06e3b,
alloc_bootmem and related functions never return NULL and always return a
zeroed region of memory.  Thus a NULL test or memset after calls to these
functions is unnecessary.

 arch/frv/mm/init.c |    2 --
 1 file changed, 2 deletions(-)

This was fixed using the following semantic patch.
(http://www.emn.fr/x-info/coccinelle/)

// <smpl>
@@
expression E;
statement S;
@@

E = \(alloc_bootmem\|alloc_bootmem_low\|alloc_bootmem_pages\|alloc_bootmem_low_pages\)(...)
... when != E
(
- BUG_ON (E == NULL);
|
- if (E == NULL) S
)

@@
expression E,E1;
@@

E = \(alloc_bootmem\|alloc_bootmem_low\|alloc_bootmem_pages\|alloc_bootmem_low_pages\)(...)
... when != E
- memset(E,0,E1);
// </smpl>

Signed-off-by: Julia Lawall <julia@...u.dk>
Signed-off-by: David Howells <dhowells@...hat.com>
---

 arch/frv/mm/init.c |    2 --
 1 files changed, 0 insertions(+), 2 deletions(-)


diff --git a/arch/frv/mm/init.c b/arch/frv/mm/init.c
index 1b851db..0708284 100644
--- a/arch/frv/mm/init.c
+++ b/arch/frv/mm/init.c
@@ -87,8 +87,6 @@ void __init paging_init(void)
 
 		pkmap_page_table = alloc_bootmem_pages(PAGE_SIZE);
 
-		memset(pkmap_page_table, 0, PAGE_SIZE);
-
 		pge = swapper_pg_dir + pgd_index_k(PKMAP_BASE);
 		pue = pud_offset(pge, PKMAP_BASE);
 		pme = pmd_offset(pue, PKMAP_BASE);

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/