From 53a256a9b925b47c7e67fc1f16ca41561a7b877c 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 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: stable@vger.kernel.org # v4.3+ Link: https://lore.kernel.org/r/ca92998ccc054b4f2bfd60ef3adbab2913171eac.1575546234.git.lukas@wunner.de Signed-off-by: Vinod Koul --- include/linux/dmaengine.h | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) diff --git a/include/linux/dmaengine.h b/include/linux/dmaengine.h index 8fcdee1c0cf9..dad4a68fa009 100644 --- a/include/linux/dmaengine.h +++ b/include/linux/dmaengine.h @@ -1364,8 +1364,11 @@ 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;