blob: c21e4315f0b2442654b2ad5b2565c96f4e695a95 [file] [log] [blame]
From 3e778dae123b06b36db20fb1cf1991151731cf3a Mon Sep 17 00:00:00 2001
From: Lukas Wunner <>
Date: Thu, 5 Dec 2019 12:54:49 +0100
Subject: [PATCH] dmaengine: Fix access to uninitialized dma_slave_caps
commit 53a256a9b925b47c7e67fc1f16ca41561a7b877c upstream.
dmaengine_desc_set_reuse() allocates a struct dma_slave_caps on the
stack, populates it using dma_get_slave_caps() and then accesses one
of its members.
However dma_get_slave_caps() may fail and this isn't accounted for,
leading to a legitimate warning of gcc-4.9 (but not newer versions):
In file included from drivers/spi/spi-bcm2835.c:19:0:
drivers/spi/spi-bcm2835.c: In function 'dmaengine_desc_set_reuse':
>> include/linux/dmaengine.h:1370:10: warning: 'caps.descriptor_reuse' is used uninitialized in this function [-Wuninitialized]
if (caps.descriptor_reuse) {
Fix it, thereby also silencing the gcc-4.9 warning.
The issue has been present for 4 years but surfaces only now that
the first caller of dmaengine_desc_set_reuse() has been added in
spi-bcm2835.c. Another user of reusable DMA descriptors has existed
for a while in pxa_camera.c, but it sets the DMA_CTRL_REUSE flag
directly instead of calling dmaengine_desc_set_reuse(). Nevertheless,
tag this commit for stable in case there are out-of-tree users.
Fixes: 272420214d26 ("dmaengine: Add DMA_CTRL_REUSE")
Reported-by: kbuild test robot <>
Signed-off-by: Lukas Wunner <>
Cc: # v4.3+
Signed-off-by: Vinod Koul <>
Signed-off-by: Paul Gortmaker <>
diff --git a/include/linux/dmaengine.h b/include/linux/dmaengine.h
index c952f987ee57..bc6c92dacca3 100644
--- a/include/linux/dmaengine.h
+++ b/include/linux/dmaengine.h
@@ -1361,8 +1361,11 @@ static inline int dma_get_slave_caps(struct dma_chan *chan,
static inline int dmaengine_desc_set_reuse(struct dma_async_tx_descriptor *tx)
struct dma_slave_caps caps;
+ int ret;
- dma_get_slave_caps(tx->chan, &caps);
+ ret = dma_get_slave_caps(tx->chan, &caps);
+ if (ret)
+ return ret;
if (caps.descriptor_reuse) {
tx->flags |= DMA_CTRL_REUSE;