From: zhaoyang huangzhaoyang@gmail.com
[ Upstream commit 5b3efa4f1479c91cb8361acef55f9c6662feba57 ]
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 Signed-off-by: Sasha Levin sashal@kernel.org --- arch/arm/mm/init.c | 5 +++++ 1 file changed, 5 insertions(+)
diff --git a/arch/arm/mm/init.c b/arch/arm/mm/init.c index 4fa12fcf1f5d8..27a40101dd3a7 100644 --- a/arch/arm/mm/init.c +++ b/arch/arm/mm/init.c @@ -195,6 +195,11 @@ 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);