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| author | Rusty Russell <rusty@rustcorp.com.au> | 2009-03-30 21:55:23 -0600 |
|---|---|---|
| committer | Rusty Russell <rusty@rustcorp.com.au> | 2009-03-30 21:55:23 +1030 |
| commit | 6afbdd059c27330eccbd85943354f94c2b83a7fe (patch) | |
| tree | 5b3becb10a07e84c5fedda8c562f5637c091cc04 | |
| parent | c5f841f1780dad7efb7eca092f60742d47f47d25 (diff) | |
| download | lwn-6afbdd059c27330eccbd85943354f94c2b83a7fe.tar.gz lwn-6afbdd059c27330eccbd85943354f94c2b83a7fe.zip | |
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
| -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 576a8318221c..82ff484bd8c8 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)) |