From 6ae0751e8bcef43bd68c3a68117f7a76895fe4db Mon Sep 17 00:00:00 2001 From: Heiko Carstens Date: Thu, 21 Nov 2013 16:22:17 +0100 Subject: s390/uaccess: add missing page table walk range check commit 71a86ef055f569b93bc6901f007bdf447dbf515f upstream. When translating a user space address, the address must be checked against the ASCE limit of the process. If the address is larger than the maximum address that is reachable with the ASCE, an ASCE type exception must be generated. The current code simply ignored the higher order bits. This resulted in an address wrap around in user space instead of an exception in user space. Reviewed-by: Gerald Schaefer Signed-off-by: Heiko Carstens Signed-off-by: Martin Schwidefsky Signed-off-by: Greg Kroah-Hartman diff --git a/arch/s390/lib/uaccess_pt.c b/arch/s390/lib/uaccess_pt.c index 1694d73..26588fd 100644 --- a/arch/s390/lib/uaccess_pt.c +++ b/arch/s390/lib/uaccess_pt.c @@ -78,11 +78,14 @@ static size_t copy_in_kernel(size_t count, void __user *to, * contains the (negative) exception code. */ #ifdef CONFIG_64BIT + static unsigned long follow_table(struct mm_struct *mm, unsigned long address, int write) { unsigned long *table = (unsigned long *)__pa(mm->pgd); + if (unlikely(address > mm->context.asce_limit - 1)) + return -0x38UL; switch (mm->context.asce_bits & _ASCE_TYPE_MASK) { case _ASCE_TYPE_REGION1: table = table + ((address >> 53) & 0x7ff); -- cgit v0.10.2