| From | Josh Poimboeuf <> | Subject | [PATCH v3 46/51] x86/unwind: warn on kernel stack corruption | Date | Fri, 12 Aug 2016 09:29:05 -0500 |
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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 <jpoimboe@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
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