From c6a9c8e51b188d049496643db2cfbb67df65190c Mon Sep 17 00:00:00 2001 From: Greg Hackmann Date: Thu, 28 Aug 2014 14:00:10 -0700 Subject: [PATCH] arm64: check for upper PAGE_SHIFT bits in pfn_valid() pfn_valid() returns a false positive when the lower (64 - PAGE_SHIFT) bits match a valid pfn but some of the upper bits are set. This caused a kernel panic in kpageflags_read() when a userspace utility parsed /proc/*/pagemap, neglected to discard the upper flag bits, and tried to lseek()+read() from the corresponding offset in /proc/kpageflags. A valid pfn will never have the upper PAGE_SHIFT bits set, so simply check for this before passing the pfn to memblock_is_memory(). Change-Id: Ief5d8cd4dd93cbecd545a634a8d5885865cb5970 Signed-off-by: Greg Hackmann --- arch/arm64/mm/init.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/arch/arm64/mm/init.c b/arch/arm64/mm/init.c index 17bf39ac83ba..325f89ff897e 100644 --- a/arch/arm64/mm/init.c +++ b/arch/arm64/mm/init.c @@ -118,9 +118,11 @@ static void __init zone_sizes_init(unsigned long min, unsigned long max) } #ifdef CONFIG_HAVE_ARCH_PFN_VALID +#define PFN_MASK ((1UL << (64 - PAGE_SHIFT)) - 1) + int pfn_valid(unsigned long pfn) { - return memblock_is_memory(pfn << PAGE_SHIFT); + return (pfn & PFN_MASK) == pfn && memblock_is_memory(pfn << PAGE_SHIFT); } EXPORT_SYMBOL(pfn_valid); #endif -- 2.20.1