linux-kernel - [PATCH 5/11] drivers/dma: Eliminate a NULL pointer dereference

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Date:	Thu, 27 May 2010 14:33:17 +0200 (CEST)
From:	Julia Lawall <julia@...u.dk>
To:	Dan Williams <dan.j.williams@...el.com>,
	linux-kernel@...r.kernel.org, kernel-janitors@...r.kernel.org
Subject: [PATCH 5/11] drivers/dma: Eliminate a NULL pointer dereference

From: Julia Lawall <julia@...u.dk>

If td_desc is NULL, just skip both kfrees.

A simplified version of the semantic match that finds this problem is as
follows: (http://coccinelle.lip6.fr/)

// <smpl>
@r exists@
expression E,E1;
identifier f;
statement S1,S2,S3;
@@

if ((E == NULL && ...) || ...)
{
  ... when != if (...) S1 else S2
      when != E = E1
* E->f
  ... when any
  return ...;
}
else S3
// </smpl>

Signed-off-by: Julia Lawall <julia@...u.dk>

---
 drivers/dma/timb_dma.c |    4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/dma/timb_dma.c b/drivers/dma/timb_dma.c
index 0172fa3..c4eb96a 100644
--- a/drivers/dma/timb_dma.c
+++ b/drivers/dma/timb_dma.c
@@ -382,7 +382,7 @@ static struct timb_dma_desc *td_alloc_init_desc(struct timb_dma_chan *td_chan)
 	td_desc = kzalloc(sizeof(struct timb_dma_desc), GFP_KERNEL);
 	if (!td_desc) {
 		dev_err(chan2dev(chan), "Failed to alloc descriptor\n");
-		goto err;
+		goto out;
 	}
 
 	td_desc->desc_list_len = td_chan->desc_elems * TIMB_DMA_DESC_SIZE;
@@ -410,7 +410,7 @@ static struct timb_dma_desc *td_alloc_init_desc(struct timb_dma_chan *td_chan)
 err:
 	kfree(td_desc->desc_list);
 	kfree(td_desc);
-
+out:
 	return NULL;
 
 }
--
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