diff options
| author | Rusty Russell <rusty@rustcorp.com.au> | 2009-03-31 01:55:04 +0000 |
|---|---|---|
| committer | Chris Wright <chrisw@sous-sol.org> | 2009-04-02 13:55:19 -0700 |
| commit | 4d25e3d0370354092b04aa338df14fb0b4c63331 (patch) | |
| tree | 27166114a01c481b4132e45f10f4c7dbf05155ab | |
| parent | ab624168973480d92c844cc6c46f97d85bedd91c (diff) | |
lguest: fix spurious BUG_ON() on invalid guest stack.
upstream commit: 6afbdd059c27330eccbd85943354f94c2b83a7fe
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
Signed-off-by: Chris Wright <chrisw@sous-sol.org>
| -rw-r--r-- | drivers/lguest/page_tables.c | 4 |
1 files changed, 3 insertions, 1 deletions
diff --git a/drivers/lguest/page_tables.c b/drivers/lguest/page_tables.c index 576a8318221..82ff484bd8c 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)) |