| Message ID | f76b49739625fce1264428155540ca7161925511.1466741835.git.luto@kernel.org (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On Thu, Jun 23, 2016 at 09:23:08PM -0700, Andy Lutomirski wrote: > If we overflow the stack, print_context_stack will abort. Detect > this case and rewind back into the valid part of the stack so that > we can trace it. > > Signed-off-by: Andy Lutomirski <luto@kernel.org> Reviewed-by: Josh Poimboeuf <jpoimboe@redhat.com>
On Fri, Jun 24, 2016 at 8:35 AM, Josh Poimboeuf <jpoimboe@redhat.com> wrote: > On Thu, Jun 23, 2016 at 09:23:08PM -0700, Andy Lutomirski wrote: >> If we overflow the stack, print_context_stack will abort. Detect >> this case and rewind back into the valid part of the stack so that >> we can trace it. >> >> Signed-off-by: Andy Lutomirski <luto@kernel.org> > > Reviewed-by: Josh Poimboeuf <jpoimboe@redhat.com> > FWIW, I'm making a trivial change here for v4: task->stack -> task_stack_page(task). Since it seems inconsequential, I'm keeping your reviewed-by. > -- > Josh
diff --git a/arch/x86/kernel/dumpstack.c b/arch/x86/kernel/dumpstack.c index 4592bc4ed3e1..4538f7ca9072 100644 --- a/arch/x86/kernel/dumpstack.c +++ b/arch/x86/kernel/dumpstack.c @@ -87,7 +87,7 @@ static inline int valid_stack_ptr(struct task_struct *task, else return 0; } - return p > t && p < t + THREAD_SIZE - size; + return p >= t && p < t + THREAD_SIZE - size; } unsigned long @@ -98,6 +98,13 @@ print_context_stack(struct task_struct *task, { struct stack_frame *frame = (struct stack_frame *)bp; + /* + * If we overflowed the stack into a guard page, jump back to the + * bottom of the usable stack. + */ + if ((unsigned long)task->stack - (unsigned long)stack < PAGE_SIZE) + stack = (unsigned long *)task->stack; + while (valid_stack_ptr(task, stack, sizeof(*stack), end)) { unsigned long addr;
If we overflow the stack, print_context_stack will abort. Detect this case and rewind back into the valid part of the stack so that we can trace it. Signed-off-by: Andy Lutomirski <luto@kernel.org> --- arch/x86/kernel/dumpstack.c | 9 ++++++++- 1 file changed, 8 insertions(+), 1 deletion(-)