From 5b3efa4f1479c91cb8361acef55f9c6662feba57 Mon Sep 17 00:00:00 2001 From: zhaoyang Date: Mon, 26 Aug 2019 04:07:37 +0100 Subject: 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 [] (stable_page_flags) from [] [46886.723264] c7 [] (kpageflags_read) from [] [46886.723280] c7 [] (proc_reg_read) from [] [46886.723290] c7 [] (__vfs_read) from [] [46886.723301] c7 [] (vfs_read) from [] [46886.723315] c7 [] (SyS_pread64) from [] (ret_fast_syscall+0x0/0x28) Signed-off-by: Zhaoyang Huang Signed-off-by: Russell King --- arch/arm/mm/init.c | 5 +++++ 1 file changed, 5 insertions(+) (limited to 'arch') diff --git a/arch/arm/mm/init.c b/arch/arm/mm/init.c index 3a65ded832df..b4be3baa83d4 100644 --- a/arch/arm/mm/init.c +++ b/arch/arm/mm/init.c @@ -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); -- cgit v1.2.3-59-g8ed1b