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* [PATCH] dma: sh: usb-dmac: Fix residue after the commit 24461d9792c2
@ 2020-05-21 11:46 Yoshihiro Shimoda
  0 siblings, 0 replies; only message in thread
From: Yoshihiro Shimoda @ 2020-05-21 11:46 UTC (permalink / raw)
  To: vkoul; +Cc: dmaengine, linux-renesas-soc, Yoshihiro Shimoda

This driver assumed that freed descriptors have "done_cookie".
But, after the commit 24461d9792c2 ("dmaengine: virt-dma: Fix
access after free in vchan_complete()"), since the desc is freed
after callback function was called, this driver could not
match any done_cookie when a client driver (renesas_usbhs driver)
calls dmaengine_tx_status() in the callback function.
So, add to check both descriptor types (freed and got) to fix
the issue.

Reported-by: Hien Dang <hien.dang.eb@renesas.com>
Fixes: 24461d9792c2 ("dmaengine: virt-dma: Fix access after free in vchan_complete()")
Signed-off-by: Yoshihiro Shimoda <yoshihiro.shimoda.uh@renesas.com>
---
 drivers/dma/sh/usb-dmac.c | 13 +++++++------
 1 file changed, 7 insertions(+), 6 deletions(-)

diff --git a/drivers/dma/sh/usb-dmac.c b/drivers/dma/sh/usb-dmac.c
index b218a01..c0adc1c8 100644
--- a/drivers/dma/sh/usb-dmac.c
+++ b/drivers/dma/sh/usb-dmac.c
@@ -488,16 +488,17 @@ static u32 usb_dmac_chan_get_residue_if_complete(struct usb_dmac_chan *chan,
 						 dma_cookie_t cookie)
 {
 	struct usb_dmac_desc *desc;
-	u32 residue = 0;
 
+	list_for_each_entry_reverse(desc, &chan->desc_got, node) {
+		if (desc->done_cookie == cookie)
+			return desc->residue;
+	}
 	list_for_each_entry_reverse(desc, &chan->desc_freed, node) {
-		if (desc->done_cookie == cookie) {
-			residue = desc->residue;
-			break;
-		}
+		if (desc->done_cookie == cookie)
+			return desc->residue;
 	}
 
-	return residue;
+	return 0;
 }
 
 static u32 usb_dmac_chan_get_residue(struct usb_dmac_chan *chan,
-- 
2.7.4


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2020-05-21 11:46 [PATCH] dma: sh: usb-dmac: Fix residue after the commit 24461d9792c2 Yoshihiro Shimoda

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