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Message-Id: <e3696f6ad079ee12ce50317a53f14ff3adb84ad1.1468270393.git.luto@kernel.org>
Date: Mon, 11 Jul 2016 13:54:03 -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 v5 30/32] x86/dumpstack: Pin the target stack in save_stack_trace_tsk()
This will prevent a crash if the target task dies before or while
dumping its stack once we start freeing task stacks early.
Signed-off-by: Andy Lutomirski <luto@...nel.org>
---
arch/x86/kernel/stacktrace.c | 5 +++++
1 file changed, 5 insertions(+)
diff --git a/arch/x86/kernel/stacktrace.c b/arch/x86/kernel/stacktrace.c
index 9ee98eefc44d..cc0826409a21 100644
--- a/arch/x86/kernel/stacktrace.c
+++ b/arch/x86/kernel/stacktrace.c
@@ -79,9 +79,14 @@ void save_stack_trace_regs(struct pt_regs *regs, struct stack_trace *trace)
void save_stack_trace_tsk(struct task_struct *tsk, struct stack_trace *trace)
{
+ if (!try_get_task_stack(tsk))
+ return;
+
dump_trace(tsk, NULL, NULL, 0, &save_stack_ops_nosched, trace);
if (trace->nr_entries < trace->max_entries)
trace->entries[trace->nr_entries++] = ULONG_MAX;
+
+ put_task_stack(tsk);
}
EXPORT_SYMBOL_GPL(save_stack_trace_tsk);
--
2.7.4
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