Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756885Ab2J1Xj5 (ORCPT ); Sun, 28 Oct 2012 19:39:57 -0400 Received: from shadbolt.e.decadent.org.uk ([88.96.1.126]:42024 "EHLO shadbolt.e.decadent.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756769Ab2J1X1r (ORCPT ); Sun, 28 Oct 2012 19:27:47 -0400 Message-Id: <20121028231558.261619374@decadent.org.uk> User-Agent: quilt/0.60-1 Date: Sun, 28 Oct 2012 23:16:45 +0000 From: Ben Hutchings To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: akpm@linux-foundation.org, alan@lxorguk.ukuu.org.uk, Denis Kirjanov , Doug Thompson , Borislav Petkov Subject: [ 069/105] amd64_edac:__amd64_set_scrub_rate(): avoid overindexing scrubrates[] In-Reply-To: <20121028231536.970033833@decadent.org.uk> X-SA-Exim-Connect-IP: 2001:470:1f08:1539:21c:bfff:fe03:f805 X-SA-Exim-Mail-From: ben@decadent.org.uk X-SA-Exim-Scanned: No (on shadbolt.decadent.org.uk); SAEximRunCond expanded to false Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2424 Lines: 66 3.2-stable review patch. If anyone has any objections, please let me know. ------------------ From: Andrew Morton commit 168bfeef7bba3f9784f7540b053e4ac72b769ce9 upstream. If none of the elements in scrubrates[] matches, this loop will cause __amd64_set_scrub_rate() to incorrectly use the n+1th element. As the function is designed to use the final scrubrates[] element in the case of no match, we can fix this bug by simply terminating the array search at the n-1th element. Boris: this code is fragile anyway, see here why: http://marc.info/?l=linux-kernel&m=135102834131236&w=2 It will be rewritten more robustly soonish. Reported-by: Denis Kirjanov Cc: Doug Thompson Signed-off-by: Andrew Morton Signed-off-by: Borislav Petkov Signed-off-by: Ben Hutchings --- drivers/edac/amd64_edac.c | 11 ++++------- 1 file changed, 4 insertions(+), 7 deletions(-) diff --git a/drivers/edac/amd64_edac.c b/drivers/edac/amd64_edac.c index 5a297a2..cc8e7c7 100644 --- a/drivers/edac/amd64_edac.c +++ b/drivers/edac/amd64_edac.c @@ -170,8 +170,11 @@ static int __amd64_set_scrub_rate(struct pci_dev *ctl, u32 new_bw, u32 min_rate) * memory controller and apply to register. Search for the first * bandwidth entry that is greater or equal than the setting requested * and program that. If at last entry, turn off DRAM scrubbing. + * + * If no suitable bandwidth is found, turn off DRAM scrubbing entirely + * by falling back to the last element in scrubrates[]. */ - for (i = 0; i < ARRAY_SIZE(scrubrates); i++) { + for (i = 0; i < ARRAY_SIZE(scrubrates) - 1; i++) { /* * skip scrub rates which aren't recommended * (see F10 BKDG, F3x58) @@ -181,12 +184,6 @@ static int __amd64_set_scrub_rate(struct pci_dev *ctl, u32 new_bw, u32 min_rate) if (scrubrates[i].bandwidth <= new_bw) break; - - /* - * if no suitable bandwidth found, turn off DRAM scrubbing - * entirely by falling back to the last element in the - * scrubrates array. - */ } scrubval = scrubrates[i].scrubval; -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/