From: Heiko Carstens Date: Thu, 21 Nov 2013 15:22:17 +0000 (+0100) Subject: s390/uaccess: add missing page table walk range check X-Git-Tag: firefly_0821_release~6453^2~124 X-Git-Url: http://demsky.eecs.uci.edu/git/?a=commitdiff_plain;h=3df594a7ac9a732413ecaad15682945715df4443;p=firefly-linux-kernel-4.4.55.git 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 50ea137a2d3c..1bf40ef57cf6 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);