linux-kernel - Re: [PATCH] dmaengine: Fix access to uninitialized dma_slave

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Message-ID: <20191211103333.GE2536@vkoul-mobl>
Date:   Wed, 11 Dec 2019 16:03:33 +0530
From:   Vinod Koul <vkoul@...nel.org>
To:     Lukas Wunner <lukas@...ner.de>
Cc:     dmaengine@...r.kernel.org, kbuild-all@...ts.01.org,
        linux-kernel@...r.kernel.org, Mark Brown <broonie@...nel.org>,
        Nathan Chancellor <natechancellor@...il.com>
Subject: Re: [PATCH] dmaengine: Fix access to uninitialized dma_slave_caps

On 05-12-19, 12:54, Lukas Wunner wrote:
> 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.

Applied, thanks

-- 
~Vinod