From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933636Ab1DNSXI (ORCPT ); Thu, 14 Apr 2011 14:23:08 -0400 Received: from mail.windriver.com ([147.11.1.11]:38265 "EHLO mail.windriver.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933206Ab1DNRqi (ORCPT ); Thu, 14 Apr 2011 13:46:38 -0400 From: Paul Gortmaker To: stable@kernel.org, linux-kernel@vger.kernel.org Cc: stable-review@kernel.org, Clemens Ladisch , Stefan Richter , Paul Gortmaker Subject: [34-longterm 059/209] firewire: ohci: fix race in AR split packet handling Date: Thu, 14 Apr 2011 13:41:29 -0400 Message-Id: <1302803039-9400-60-git-send-email-paul.gortmaker@windriver.com> X-Mailer: git-send-email 1.7.4.4 In-Reply-To: <1302803039-9400-1-git-send-email-paul.gortmaker@windriver.com> References: <1302803039-9400-1-git-send-email-paul.gortmaker@windriver.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Clemens Ladisch ===================================================================== | This is a commit scheduled for the next v2.6.34 longterm release. | | If you see a problem with using this for longterm, please comment.| ===================================================================== commit a1f805e5e73a8fe166b71c6592d3837df0cd5e2e upstream. When handling an AR buffer that has been completely filled, we assumed that its descriptor will not be read by the controller and can be overwritten. However, when the last received packet happens to end at the end of the buffer, the controller might not yet have moved on to the next buffer and might read the branch address later. If we overwrite and free the page before that, the DMA context will either go dead because of an invalid Z value, or go off into some random memory. To fix this, ensure that the descriptor does not get overwritten by using only the actual buffer instead of the entire page for reassembling the split packet. Furthermore, to avoid freeing the page too early, move on to the next buffer only when some data in it guarantees that the controller has moved on. This should eliminate the remaining firewire-net problems. Signed-off-by: Clemens Ladisch Tested-by: Maxim Levitsky Signed-off-by: Stefan Richter Signed-off-by: Paul Gortmaker --- drivers/firewire/ohci.c | 35 +++++++++++++++++++++-------------- 1 files changed, 21 insertions(+), 14 deletions(-) diff --git a/drivers/firewire/ohci.c b/drivers/firewire/ohci.c index b1b0281..3816889 100644 --- a/drivers/firewire/ohci.c +++ b/drivers/firewire/ohci.c @@ -647,20 +647,19 @@ static void ar_context_tasklet(unsigned long data) */ offset = offsetof(struct ar_buffer, data); - start = buffer = ab; + start = ab; start_bus = le32_to_cpu(ab->descriptor.data_address) - offset; + buffer = ab->data; ab = ab->next; d = &ab->descriptor; - size = buffer + PAGE_SIZE - ctx->pointer; + size = start + PAGE_SIZE - ctx->pointer; /* valid buffer data in the next page */ rest = le16_to_cpu(d->req_count) - le16_to_cpu(d->res_count); /* what actually fits in this page */ - size2 = min(rest, (size_t)PAGE_SIZE - size); + size2 = min(rest, (size_t)PAGE_SIZE - offset - size); memmove(buffer, ctx->pointer, size); memcpy(buffer + size, ab->data, size2); - ctx->current_buffer = ab; - ctx->pointer = (void *) ab->data + rest; while (size > 0) { void *next = handle_ar_packet(ctx, buffer); @@ -679,22 +678,30 @@ static void ar_context_tasklet(unsigned long data) size -= pktsize; /* fill up this page again */ size3 = min(rest - size2, - (size_t)PAGE_SIZE - size - size2); + (size_t)PAGE_SIZE - offset - size - size2); memcpy(buffer + size + size2, (void *) ab->data + size2, size3); size2 += size3; } - /* handle the packets that are fully in the next page */ - buffer = (void *) ab->data + (buffer - (start + size)); - end = (void *) ab->data + rest; + if (rest > 0) { + /* handle the packets that are fully in the next page */ + buffer = (void *) ab->data + + (buffer - (start + offset + size)); + end = (void *) ab->data + rest; - while (buffer < end) - buffer = handle_ar_packet(ctx, buffer); + while (buffer < end) + buffer = handle_ar_packet(ctx, buffer); - dma_free_coherent(ohci->card.device, PAGE_SIZE, - start, start_bus); - ar_context_add_page(ctx); + ctx->current_buffer = ab; + ctx->pointer = end; + + dma_free_coherent(ohci->card.device, PAGE_SIZE, + start, start_bus); + ar_context_add_page(ctx); + } else { + ctx->pointer = start + PAGE_SIZE; + } } else { buffer = ctx->pointer; ctx->pointer = end = -- 1.7.4.4