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authorRusty Russell <rusty@rustcorp.com.au>2009-03-30 21:55:23 -0600
committerRusty Russell <rusty@rustcorp.com.au>2009-03-30 21:55:23 +1030
commit6afbdd059c27330eccbd85943354f94c2b83a7fe (patch)
tree5b3becb10a07e84c5fedda8c562f5637c091cc04 /drivers/lguest
parentc5f841f1780dad7efb7eca092f60742d47f47d25 (diff)
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lguest: fix spurious BUG_ON() on invalid guest stack.
Impact: fix crash on misbehaving guest gpte_addr() contains a BUG_ON(), insisting that the present flag is set. We need to return before we call it if that isn't the case. Signed-off-by: Rusty Russell <rusty@rustcorp.com.au> Cc: stable@kernel.org
Diffstat (limited to 'drivers/lguest')
-rw-r--r--drivers/lguest/page_tables.c4
1 files changed, 3 insertions, 1 deletions
diff --git a/drivers/lguest/page_tables.c b/drivers/lguest/page_tables.c
index 576a831..82ff484 100644
--- a/drivers/lguest/page_tables.c
+++ b/drivers/lguest/page_tables.c
@@ -373,8 +373,10 @@ unsigned long guest_pa(struct lg_cpu *cpu, unsigned long vaddr)
/* First step: get the top-level Guest page table entry. */
gpgd = lgread(cpu, gpgd_addr(cpu, vaddr), pgd_t);
/* Toplevel not present? We can't map it in. */
- if (!(pgd_flags(gpgd) & _PAGE_PRESENT))
+ if (!(pgd_flags(gpgd) & _PAGE_PRESENT)) {
kill_guest(cpu, "Bad address %#lx", vaddr);
+ return -1UL;
+ }
gpte = lgread(cpu, gpte_addr(gpgd, vaddr), pte_t);
if (!(pte_flags(gpte) & _PAGE_PRESENT))