[tip:x86/asm] x86/unwind: Detect bad stack return address

[tip-bot for Josh Poimboeuf]

Commit-ID:  b6959a362177053c1c90db6dc1af25b6bddd8548
Gitweb: http://git.kernel.org/tip/b6959a362177053c1c90db6dc1af25b6bddd8548
Author: Josh Poimboeuf 
AuthorDate: Wed, 26 Oct 2016 10:41:51 -0500
Committer:  Ingo Molnar 
CommitDate: Thu, 27 Oct 2016 08:32:38 +0200

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.jpoim...@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 9be9a8f..5639db6 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, >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);
 

[tip:x86/asm] x86/unwind: Detect bad stack return address

[tip-bot for Josh Poimboeuf]

Commit-ID:  b6959a362177053c1c90db6dc1af25b6bddd8548
Gitweb: http://git.kernel.org/tip/b6959a362177053c1c90db6dc1af25b6bddd8548
Author: Josh Poimboeuf 
AuthorDate: Wed, 26 Oct 2016 10:41:51 -0500
Committer:  Ingo Molnar 
CommitDate: Thu, 27 Oct 2016 08:32:38 +0200

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.jpoim...@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 9be9a8f..5639db6 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, >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);