proc: Fix return address printk conversion specifer in /proc/<pid>/stack

When printing call return addresses found on a stack, /proc/<pid>/stack
can sometimes give a confusing result.  If the call instruction was the
last instruction in the function (which can happen when calling a
noreturn function), '%pS' will incorrectly display the name of the
function which happens to be next in the object code, rather than the
name of the actual calling function.

Use '%pB' instead, which was created for this exact purpose.

Signed-off-by: Josh Poimboeuf <[email protected]>
Cc: Andy Lutomirski <[email protected]>
Cc: Andy Lutomirski <[email protected]>
Cc: Borislav Petkov <[email protected]>
Cc: Brian Gerst <[email protected]>
Cc: Byungchul Park <[email protected]>
Cc: Denys Vlasenko <[email protected]>
Cc: Frederic Weisbecker <[email protected]>
Cc: H. Peter Anvin <[email protected]>
Cc: Kees Cook <[email protected]>
Cc: Linus Torvalds <[email protected]>
Cc: Nilay Vaish <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Steven Rostedt <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Link: http://lkml.kernel.org/r/47ad2821e5ebdbed1fbf83fb85424ae4fbdf8b6e.1471535549.git.jpoimboe@redhat.com
Signed-off-by: Ingo Molnar <[email protected]>

diff --git a/fs/proc/base.c b/fs/proc/base.c
index 54e270262979b6f331a31b132171c0b74b92b920..e9ff186c723fc193c8d26e70322f3a52c5af6b0b 100644 (file)
--- a/fs/proc/base.c
+++ b/fs/proc/base.c
@@ -483,7 +483,7 @@ static int proc_pid_stack(struct seq_file *m, struct pid_namespace *ns,
                save_stack_trace_tsk(task, &trace);
 
                for (i = 0; i < trace.nr_entries; i++) {
-                       seq_printf(m, "[<%pK>] %pS\n",
+                       seq_printf(m, "[<%pK>] %pB\n",
                                   (void *)entries[i], (void *)entries[i]);
                }
                unlock_trace(task);