Messages in this thread | | | Date | Tue, 17 Apr 2018 15:54:07 +0200 | From | Thomas Petazzoni <> | Subject | Re: [PATCH] sh: mm: Fix unprotected access to struct device |
| |
Hello,
On Tue, 17 Apr 2018 15:35:23 +0200, Jacopo Mondi wrote: > With commit ce88313069c36eef80f21fd7 ("arch/sh: make the DMA mapping > operations observe dev->dma_pfn_offset") the generic DMA allocation > function on which the SH 'dma_alloc_coherent()' function relies on, > access the 'dma_pfn_offset' field of struct device. > > Unfortunately the 'dma_generic_alloc_coherent()' function is called from > several places with a NULL struct device argument, halting the CPU > during the boot process. > > This patch fixes the issue protecting access to dev->dma_pfn_offset, > with a trivial check for validity. It also passes a valid 'struct device' > in the 'platform_resource_setup_memory' function which is the main user > of 'dma_alloc_coherent()', and inserting a WARN_ON() check to make future > (and existing) bogus users of this function they're should provide a valid > 'struct device' whenever possible. > > Fixes: ce88313069c36eef80f21fd7 ("arch/sh: make the DMA mapping operations observe dev->dma_pfn_offset") > Signed-off-by: Jacopo Mondi <jacopo+renesas@jmondi.org>
I would have done two commits here, one to fix:
dma_alloc_coherent(&pdev->dev, memsize, &dma_handle, GFP_KERNEL);
and one to switch to the WARN_ON + if(dev) model. But I don't really care either way, so:
Reviewed-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>
Note that even with the if (dev) check, you don't avoid all possible regressions. For example, some parts of the sh_eth driver were passing a non-NULL struct device, but it was the wrong struct device (the one inside struct net_device, and not the one part of struct platform_device). I fixed that for sh_eth, but there could be other drivers doing bogus things.
Best regards,
Thomas -- Thomas Petazzoni, CTO, Bootlin (formerly Free Electrons) Embedded Linux and Kernel engineering https://bootlin.com
| |