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powerpc/kasan: Fix addr error caused by page alignment
[ Upstream commit4a7aee9620
] In kasan_init_region, when k_start is not page aligned, at the begin of for loop, k_cur = k_start & PAGE_MASK is less than k_start, and then `va = block + k_cur - k_start` is less than block, the addr va is invalid, because the memory address space from va to block is not alloced by memblock_alloc, which will not be reserved by memblock_reserve later, it will be used by other places. As a result, memory overwriting occurs. for example: int __init __weak kasan_init_region(void *start, size_t size) { [...] /* if say block(dcd97000) k_start(feef7400) k_end(feeff3fe) */ block = memblock_alloc(k_end - k_start, PAGE_SIZE); [...] for (k_cur = k_start & PAGE_MASK; k_cur < k_end; k_cur += PAGE_SIZE) { /* at the begin of for loop * block(dcd97000) va(dcd96c00) k_cur(feef7000) k_start(feef7400) * va(dcd96c00) is less than block(dcd97000), va is invalid */ void *va = block + k_cur - k_start; [...] } [...] } Therefore, page alignment is performed on k_start before memblock_alloc() to ensure the validity of the VA address. Fixes:663c0c9496
("powerpc/kasan: Fix shadow area set up for modules.") Signed-off-by: Jiangfeng Xiao <xiaojiangfeng@huawei.com> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://msgid.link/1705974359-43790-1-git-send-email-xiaojiangfeng@huawei.com Signed-off-by: Sasha Levin <sashal@kernel.org>
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@ -64,6 +64,7 @@ int __init __weak kasan_init_region(void *start, size_t size)
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if (ret)
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return ret;
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k_start = k_start & PAGE_MASK;
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block = memblock_alloc(k_end - k_start, PAGE_SIZE);
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if (!block)
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return -ENOMEM;
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