From b6959a362177053c1c90db6dc1af25b6bddd8548 Mon Sep 17 00:00:00 2001 From: Josh Poimboeuf Date: Wed, 26 Oct 2016 10:41:51 -0500 Subject: [PATCH] x86/unwind: Detect bad stack return address If __kernel_text_address() doesn't recognize a return address on the stack, it probably means that it's some generated code which __kernel_text_address() doesn't know about yet. Otherwise there's probably some stack corruption. Either way, warn about it. 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 Cc: Andy Lutomirski Cc: Borislav Petkov Cc: Brian Gerst Cc: Denys Vlasenko Cc: H. Peter Anvin Cc: Linus Torvalds Cc: Peter Zijlstra Cc: Thomas Gleixner Link: http://lkml.kernel.org/r/2d897898f324e275943b590d160b55e482bba65f.1477496147.git.jpoimboe@redhat.com Signed-off-by: Ingo Molnar --- arch/x86/kernel/unwind_frame.c | 10 +++++++++- 1 file changed, 9 insertions(+), 1 deletion(-) diff --git a/arch/x86/kernel/unwind_frame.c b/arch/x86/kernel/unwind_frame.c index 9be9a8f8c5df..5639db619c03 100644 --- a/arch/x86/kernel/unwind_frame.c +++ b/arch/x86/kernel/unwind_frame.c @@ -20,7 +20,15 @@ unsigned long unwind_get_return_address(struct unwind_state *state) addr = ftrace_graph_ret_addr(state->task, &state->graph_idx, *addr_p, addr_p); - return __kernel_text_address(addr) ? addr : 0; + if (!__kernel_text_address(addr)) { + printk_deferred_once(KERN_WARNING + "WARNING: unrecognized kernel stack return address %p at %p in %s:%d\n", + (void *)addr, addr_p, state->task->comm, + state->task->pid); + return 0; + } + + return addr; } EXPORT_SYMBOL_GPL(unwind_get_return_address); -- 2.20.1