From 4623c28e222d82f87537ef66db61ebcfbd8306db Mon Sep 17 00:00:00 2001 From: Rusty Russell Date: Thu, 5 Sep 2013 17:45:39 +0930 Subject: [PATCH] lguest: fix BUG_ON() in invalid guest page table. If we discover the entry is invalid, we kill the guest, but we must avoid calling gpte_addr() on the invalid pmd, otherwise: kernel BUG at drivers/lguest/page_tables.c:157! Signed-off-by: Rusty Russell --- drivers/lguest/page_tables.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/drivers/lguest/page_tables.c b/drivers/lguest/page_tables.c index a35d8d100165..bfb39bb56ef1 100644 --- a/drivers/lguest/page_tables.c +++ b/drivers/lguest/page_tables.c @@ -669,8 +669,10 @@ unsigned long guest_pa(struct lg_cpu *cpu, unsigned long vaddr) #ifdef CONFIG_X86_PAE gpmd = lgread(cpu, gpmd_addr(gpgd, vaddr), pmd_t); - if (!(pmd_flags(gpmd) & _PAGE_PRESENT)) + if (!(pmd_flags(gpmd) & _PAGE_PRESENT)) { kill_guest(cpu, "Bad address %#lx", vaddr); + return -1UL; + } gpte = lgread(cpu, gpte_addr(cpu, gpmd, vaddr), pte_t); #else gpte = lgread(cpu, gpte_addr(cpu, gpgd, vaddr), pte_t); -- 2.20.1