Commit 5b3efa4f authored Aug 26, 2019 by zhaoyang Committed by Russell King Aug 28, 2019

ARM: 8901/1: add a criteria for pfn_valid of arm



pfn_valid can be wrong when parsing a invalid pfn whose phys address
exceeds BITS_PER_LONG as the MSB will be trimed when shifted.

The issue originally arise from bellowing call stack, which corresponding to
an access of the /proc/kpageflags from userspace with a invalid pfn parameter
and leads to kernel panic.

[46886.723249] c7 [<c031ff98>] (stable_page_flags) from [<c03203f8>]
[46886.723264] c7 [<c0320368>] (kpageflags_read) from [<c0312030>]
[46886.723280] c7 [<c0311fb0>] (proc_reg_read) from [<c02a6e6c>]
[46886.723290] c7 [<c02a6e24>] (__vfs_read) from [<c02a7018>]
[46886.723301] c7 [<c02a6f74>] (vfs_read) from [<c02a778c>]
[46886.723315] c7 [<c02a770c>] (SyS_pread64) from [<c0108620>]
(ret_fast_syscall+0x0/0x28)

Signed-off-by: Zhaoyang Huang <zhaoyang.huang@unisoc.com>
Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>

parent 69389837

arch/arm/mm/init.c

+5 −0

Original line number	Diff line number	Diff line
		@@ -175,6 +175,11 @@ static void __init zone_sizes_init(unsigned long min, unsigned long max_low,
		#ifdef CONFIG_HAVE_ARCH_PFN_VALID
		int pfn_valid(unsigned long pfn)
		{
		phys_addr_t addr = __pfn_to_phys(pfn);

		if (__phys_to_pfn(addr) != pfn)
		return 0;

		return memblock_is_map_memory(__pfn_to_phys(pfn));
		}
		EXPORT_SYMBOL(pfn_valid);

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