[PATCH 5.15 65/69] ARM: 9216/1: Fix MAX_DMA_ADDRESS overflow

Greg Kroah-Hartman
2022-08-01T12:07:24Z

From: Florian Fainelli <f.fainelli@gmail.com>

[ Upstream commit fb0fd3469ead5b937293c213daa1f589b4b7ce46 ]

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 thanks to CONFIG_DEBUG_VIRTUAL on the bcm2711 platform
where we define a dma_zone_size of 1GB and we have a PAGE_OFFSET value
of 0xc000_0000 (CONFIG_VMSPLIT_3G) leading to MAX_DMA_ADDRESS being
0x1_0000_0000 which overflows the unsigned long type used throughout
__pa() and then __virt_addr_valid(). Because the virtual address passed
to __virt_addr_valid() would now be 0, the function would loudly warn
and flood the kernel log, 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>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
arch/arm/include/asm/dma.h | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/arm/include/asm/dma.h b/arch/arm/include/asm/dma.h
index a81dda65c576..45180a2cc47c 100644
--- 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) ? \
+ arm_dma_zone_size && arm_dma_zone_size < (0x100000000ULL - PAGE_OFFSET) ? \
(PAGE_OFFSET + arm_dma_zone_size) : 0xffffffffUL; })
#endif

--
2.35.1