linux-kernel - [PATCH v3 09/13] x86/dumpstack: When dumping stack bytes due to OOPS, start with regs->sp

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Message-Id: <ed0f9bcabc61d44bf745dbf286342f74ab304787.1466466093.git.luto@kernel.org>
Date:	Mon, 20 Jun 2016 16:43:39 -0700
From:	Andy Lutomirski <luto@...nel.org>
To:	x86@...nel.org, linux-kernel@...r.kernel.org
Cc:	linux-arch@...r.kernel.org, Borislav Petkov <bp@...en8.de>,
	Nadav Amit <nadav.amit@...il.com>,
	Kees Cook <keescook@...omium.org>,
	Brian Gerst <brgerst@...il.com>,
	"kernel-hardening@...ts.openwall.com" 
	<kernel-hardening@...ts.openwall.com>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	Josh Poimboeuf <jpoimboe@...hat.com>,
	Jann Horn <jann@...jh.net>,
	Heiko Carstens <heiko.carstens@...ibm.com>,
	Andy Lutomirski <luto@...nel.org>
Subject: [PATCH v3 09/13] x86/dumpstack: When dumping stack bytes due to OOPS, start with regs->sp

The comment suggests that show_stack(NULL, NULL) should backtrace
the current context, but the code doesn't match the comment.  If
regs are given, start the "Stack:" hexdump at regs->sp.

Signed-off-by: Andy Lutomirski <luto@...nel.org>
---
 arch/x86/kernel/dumpstack_32.c | 4 +++-
 arch/x86/kernel/dumpstack_64.c | 4 +++-
 2 files changed, 6 insertions(+), 2 deletions(-)

diff --git a/arch/x86/kernel/dumpstack_32.c b/arch/x86/kernel/dumpstack_32.c
index 464ffd69b92e..91069ebe3c87 100644
--- a/arch/x86/kernel/dumpstack_32.c
+++ b/arch/x86/kernel/dumpstack_32.c
@@ -98,7 +98,9 @@ show_stack_log_lvl(struct task_struct *task, struct pt_regs *regs,
 	int i;
 
 	if (sp == NULL) {
-		if (task)
+		if (regs)
+			sp = (unsigned long *)regs->sp;
+		else if (task)
 			sp = (unsigned long *)task->thread.sp;
 		else
 			sp = (unsigned long *)&sp;
diff --git a/arch/x86/kernel/dumpstack_64.c b/arch/x86/kernel/dumpstack_64.c
index 5f1c6266eb30..603356a5597a 100644
--- a/arch/x86/kernel/dumpstack_64.c
+++ b/arch/x86/kernel/dumpstack_64.c
@@ -266,7 +266,9 @@ show_stack_log_lvl(struct task_struct *task, struct pt_regs *regs,
 	 * back trace for this cpu:
 	 */
 	if (sp == NULL) {
-		if (task)
+		if (regs)
+			sp = (unsigned long *)regs->sp;
+		else if (task)
 			sp = (unsigned long *)task->thread.sp;
 		else
 			sp = (unsigned long *)&sp;
-- 
2.5.5