Detect situations in the unwinder where the frame pointer refers to a
bad address, and print an appropriate warning.
Use printk_deferred_once() because the unwinder can be called with the
console lock by lockdep via save_stack_trace().
Signed-off-by: Josh Poimboeuf <jpoim...@redhat.com>
---
arch/x86/kernel/unwind_frame.c | 14 +++++++++++++-
1 file changed, 13 insertions(+), 1 deletion(-)
diff --git a/arch/x86/kernel/unwind_frame.c b/arch/x86/kernel/unwind_frame.c
index d2480a3..cde900e 100644
--- a/arch/x86/kernel/unwind_frame.c
+++ b/arch/x86/kernel/unwind_frame.c
@@ -130,7 +130,8 @@ bool unwind_next_frame(struct unwind_state *state)
/* make sure the next frame's data is accessible */
if (!update_stack_state(state, next_sp, next_len))
- return false;
+ goto bad_address;
+
/* move to the next frame */
if (regs) {
state->regs = regs;
@@ -142,6 +143,17 @@ bool unwind_next_frame(struct unwind_state *state)
return true;
+bad_address:
+ if (state->regs)
+ printk_deferred_once(KERN_WARNING
+ "WARNING: kernel stack regs at %p in %s:%d has bad 'bp'
value %p\n",
+ state->regs, state->task->comm,
+ state->task->pid, next_bp);
+ else
+ printk_deferred_once(KERN_WARNING
+ "WARNING: kernel stack frame pointer at %p in %s:%d has
bad value %p\n",
+ state->bp, state->task->comm,
+ state->task->pid, next_bp);
the_end:
state->stack_info.type = STACK_TYPE_UNKNOWN;
return false;
--
2.7.4
