Messages in this thread | | | Date | Wed, 6 Jul 2022 13:26:59 -0700 | Subject | Re: [PATCH v2] ARM: Fix MAX_DMA_ADDRESS overflow | From | Florian Fainelli <> |
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On 7/6/22 12:44, Geert Uytterhoeven wrote: > Hi Florian, > > On Wed, Jul 6, 2022 at 6:46 PM Florian Fainelli <f.fainelli@gmail.com> wrote: >> Commit 26f09e9b3a06 ("mm/memblock: add memblock memory allocation apis") >> added a check to determine whether arm_dma_zone_size is exceeding the >> amount of kernel virtual address space available between the upper 4GB >> virtual address limit and PAGE_OFFSET in order to provide a suitable >> definition of MAX_DMA_ADDRESS that should fit within the 32-bit virtual >> address space. The quantity used for comparison was off by a missing >> trailing 0, leading to MAX_DMA_ADDRESS to be overflowing a 32-bit >> quantity. >> >> This was caught with the bcm2711 platforms which defines a dma_zone_size >> of 1GB, and using a PAGE_OFFSET of 0xc000_0000 (CONFIG_VMSPLIT_3G) with >> CONFIG_DEBUG_VIRTUAL enabled would lead to MAX_DMA_ADDRESS being >> 0x1_0000_0000 which overflows the unsigned long type used throughout >> __pa() and __virt_addr_valid(). Because the virtual address passed to >> __virt_addr_valid() would now be 0, the function would loudly warn, thus >> making the platform unable to boot properly. >> >> Fixes: 26f09e9b3a06 ("mm/memblock: add memblock memory allocation apis") >> Signed-off-by: Florian Fainelli <f.fainelli@gmail.com> >> --- >> Changes in v2: >> >> - simplify the patch and drop the first patch that attempted to fix an >> off by one in the calculation. > > Thanks for the update! > >> --- a/arch/arm/include/asm/dma.h >> +++ b/arch/arm/include/asm/dma.h >> @@ -10,7 +10,7 @@ >> #else >> #define MAX_DMA_ADDRESS ({ \ >> extern phys_addr_t arm_dma_zone_size; \ >> - arm_dma_zone_size && arm_dma_zone_size < (0x10000000 - PAGE_OFFSET) ? \ > ^^^^^^^^^^ > 0x10000000ULL, as the constant doesn't fit in 32-bit. > However, both gcc (9.4.0) and sparse don't seem to complain about > the missing suffix (anymore?).
Thanks, I will the ULL suffix in v3. -- Florian
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