linux-kernel - [PATCH 3.13.y-ckt 053/132] dmaengine: mv_xor: bug fix for racing condition in descriptors cleanup

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: <1437616850-23266-54-git-send-email-kamal@canonical.com>
Date:	Wed, 22 Jul 2015 18:59:31 -0700
From:	Kamal Mostafa <kamal@...onical.com>
To:	linux-kernel@...r.kernel.org, stable@...r.kernel.org,
	kernel-team@...ts.ubuntu.com
Cc:	Lior Amsalem <alior@...vell.com>,
	Maxime Ripard <maxime.ripard@...e-electrons.com>,
	Vinod Koul <vinod.koul@...el.com>,
	Kamal Mostafa <kamal@...onical.com>
Subject: [PATCH 3.13.y-ckt 053/132] dmaengine: mv_xor: bug fix for racing condition in descriptors cleanup

3.13.11-ckt24 -stable review patch.  If anyone has any objections, please let me know.

------------------

From: Lior Amsalem <alior@...vell.com>

commit 9136291f1dbc1d4d1cacd2840fb35f4f3ce16c46 upstream.

This patch fixes a bug in the XOR driver where the cleanup function can be
called and free descriptors that never been processed by the engine (which
result in data errors).

The cleanup function will free descriptors based on the ownership bit in
the descriptors.

Fixes: ff7b04796d98 ("dmaengine: DMA engine driver for Marvell XOR engine")
Signed-off-by: Lior Amsalem <alior@...vell.com>
Signed-off-by: Maxime Ripard <maxime.ripard@...e-electrons.com>
Reviewed-by: Ofer Heifetz <oferh@...vell.com>
Signed-off-by: Vinod Koul <vinod.koul@...el.com>
Signed-off-by: Kamal Mostafa <kamal@...onical.com>
---
 drivers/dma/mv_xor.c | 72 +++++++++++++++++++++++++++++++++-------------------
 drivers/dma/mv_xor.h |  1 +
 2 files changed, 47 insertions(+), 26 deletions(-)

diff --git a/drivers/dma/mv_xor.c b/drivers/dma/mv_xor.c
index 29c8a06..b01f711 100644
--- a/drivers/dma/mv_xor.c
+++ b/drivers/dma/mv_xor.c
@@ -316,7 +316,8 @@ static void __mv_xor_slot_cleanup(struct mv_xor_chan *mv_chan)
 	dma_cookie_t cookie = 0;
 	int busy = mv_chan_is_busy(mv_chan);
 	u32 current_desc = mv_chan_get_current_desc(mv_chan);
-	int seen_current = 0;
+	int current_cleaned = 0;
+	struct mv_xor_desc *hw_desc;
 
 	dev_dbg(mv_chan_to_devp(mv_chan), "%s %d\n", __func__, __LINE__);
 	dev_dbg(mv_chan_to_devp(mv_chan), "current_desc %x\n", current_desc);
@@ -328,38 +329,57 @@ static void __mv_xor_slot_cleanup(struct mv_xor_chan *mv_chan)
 
 	list_for_each_entry_safe(iter, _iter, &mv_chan->chain,
 					chain_node) {
-		prefetch(_iter);
-		prefetch(&_iter->async_tx);
 
-		/* do not advance past the current descriptor loaded into the
-		 * hardware channel, subsequent descriptors are either in
-		 * process or have not been submitted
-		 */
-		if (seen_current)
-			break;
+		/* clean finished descriptors */
+		hw_desc = iter->hw_desc;
+		if (hw_desc->status & XOR_DESC_SUCCESS) {
+			cookie = mv_xor_run_tx_complete_actions(iter, mv_chan,
+								cookie);
 
-		/* stop the search if we reach the current descriptor and the
-		 * channel is busy
-		 */
-		if (iter->async_tx.phys == current_desc) {
-			seen_current = 1;
-			if (busy)
+			/* done processing desc, clean slot */
+			mv_xor_clean_slot(iter, mv_chan);
+
+			/* break if we did cleaned the current */
+			if (iter->async_tx.phys == current_desc) {
+				current_cleaned = 1;
+				break;
+			}
+		} else {
+			if (iter->async_tx.phys == current_desc) {
+				current_cleaned = 0;
 				break;
+			}
 		}
-
-		cookie = mv_xor_run_tx_complete_actions(iter, mv_chan, cookie);
-
-		if (mv_xor_clean_slot(iter, mv_chan))
-			break;
 	}
 
 	if ((busy == 0) && !list_empty(&mv_chan->chain)) {
-		struct mv_xor_desc_slot *chain_head;
-		chain_head = list_entry(mv_chan->chain.next,
-					struct mv_xor_desc_slot,
-					chain_node);
-
-		mv_xor_start_new_chain(mv_chan, chain_head);
+		if (current_cleaned) {
+			/*
+			 * current descriptor cleaned and removed, run
+			 * from list head
+			 */
+			iter = list_entry(mv_chan->chain.next,
+					  struct mv_xor_desc_slot,
+					  chain_node);
+			mv_xor_start_new_chain(mv_chan, iter);
+		} else {
+			if (!list_is_last(&iter->chain_node, &mv_chan->chain)) {
+				/*
+				 * descriptors are still waiting after
+				 * current, trigger them
+				 */
+				iter = list_entry(iter->chain_node.next,
+						  struct mv_xor_desc_slot,
+						  chain_node);
+				mv_xor_start_new_chain(mv_chan, iter);
+			} else {
+				/*
+				 * some descriptors are still waiting
+				 * to be cleaned
+				 */
+				tasklet_schedule(&mv_chan->irq_tasklet);
+			}
+		}
 	}
 
 	if (cookie > 0)
diff --git a/drivers/dma/mv_xor.h b/drivers/dma/mv_xor.h
index d074922..5d14e4b 100644
--- a/drivers/dma/mv_xor.h
+++ b/drivers/dma/mv_xor.h
@@ -33,6 +33,7 @@
 #define XOR_OPERATION_MODE_XOR		0
 #define XOR_OPERATION_MODE_MEMCPY	2
 #define XOR_DESCRIPTOR_SWAP		BIT(14)
+#define XOR_DESC_SUCCESS		0x40000000
 
 #define XOR_CURR_DESC(chan)	(chan->mmr_high_base + 0x10 + (chan->idx * 4))
 #define XOR_NEXT_DESC(chan)	(chan->mmr_high_base + 0x00 + (chan->idx * 4))
-- 
1.9.1

--
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/