Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1761458Ab2ELASr (ORCPT ); Fri, 11 May 2012 20:18:47 -0400 Received: from mail-pb0-f46.google.com ([209.85.160.46]:55013 "EHLO mail-pb0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754894Ab2ELASo (ORCPT ); Fri, 11 May 2012 20:18:44 -0400 Date: Fri, 11 May 2012 17:17:17 -0700 From: Anton Vorontsov To: Greg Kroah-Hartman , Kees Cook , Colin Cross Cc: Arnd Bergmann , John Stultz , arve@android.com, Rebecca Schultz Zavin , Jesper Juhl , Randy Dunlap , Stephen Boyd , Thomas Meyer , Andrew Morton , Marco Stornelli , WANG Cong , linux-kernel@vger.kernel.org, devel@driverdev.osuosl.org, linaro-kernel@lists.linaro.org, patches@linaro.org, kernel-team@android.com Subject: [PATCH 02/11] persistent_ram: Fix buffer size clamping during writes Message-ID: <20120512001717.GB14782@lizard> References: <20120512001506.GA8653@lizard> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20120512001506.GA8653@lizard> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2090 Lines: 63 This is a longstanding bug, almost unnoticeable when calling persistent_ram_write() for small buffers. But when called for large data buffers, the write routine behaves incorrectly, as the size may never update: instead of clamping the size to the maximum buffer size, buffer_size_add_clamp() returns an error (which is never checked by the write routine, btw). To fix this, we now use buffer_size_add() that actually clamps the size to the max value. Also remove buffer_size_add_clamp(), it is no longer needed. Signed-off-by: Anton Vorontsov --- drivers/staging/android/persistent_ram.c | 19 +------------------ 1 file changed, 1 insertion(+), 18 deletions(-) diff --git a/drivers/staging/android/persistent_ram.c b/drivers/staging/android/persistent_ram.c index 12444fd..13a12bc 100644 --- a/drivers/staging/android/persistent_ram.c +++ b/drivers/staging/android/persistent_ram.c @@ -79,23 +79,6 @@ static inline void buffer_size_add(struct persistent_ram_zone *prz, size_t a) } while (atomic_cmpxchg(&prz->buffer->size, old, new) != old); } -/* increase the size counter, retuning an error if it hits the max size */ -static inline ssize_t buffer_size_add_clamp(struct persistent_ram_zone *prz, - size_t a) -{ - size_t old; - size_t new; - - do { - old = atomic_read(&prz->buffer->size); - new = old + a; - if (new > prz->buffer_size) - return -ENOMEM; - } while (atomic_cmpxchg(&prz->buffer->size, old, new) != old); - - return 0; -} - static void notrace persistent_ram_encode_rs8(struct persistent_ram_zone *prz, uint8_t *data, size_t len, uint8_t *ecc) { @@ -300,7 +283,7 @@ int notrace persistent_ram_write(struct persistent_ram_zone *prz, c = prz->buffer_size; } - buffer_size_add_clamp(prz, c); + buffer_size_add(prz, c); start = buffer_start_add(prz, c); -- 1.7.9.2 -- 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/