From fad90d4bfa8d29bba49f7c44c21799f819fbe7a8 Mon Sep 17 00:00:00 2001
From: Masami Hiramatsu <mhiramat@kernel.org>
Date: Tue, 3 Sep 2019 20:08:21 +0900
Subject: kprobes: Prohibit probing on BUG() and WARN() address

[ Upstream commit e336b4027775cb458dc713745e526fa1a1996b2a ]

Since BUG() and WARN() may use a trap (e.g. UD2 on x86) to
get the address where the BUG() has occurred, kprobes can not
do single-step out-of-line that instruction. So prohibit
probing on such address.

Without this fix, if someone put a kprobe on WARN(), the
kernel will crash with invalid opcode error instead of
outputing warning message, because kernel can not find
correct bug address.

Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
Acked-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Acked-by: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com>
Cc: Anil S Keshavamurthy <anil.s.keshavamurthy@intel.com>
Cc: David S . Miller <davem@davemloft.net>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Naveen N . Rao <naveen.n.rao@linux.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: https://lkml.kernel.org/r/156750890133.19112.3393666300746167111.stgit@devnote2
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 include/linux/bug.h | 5 +++++
 1 file changed, 5 insertions(+)

(limited to 'include')

diff --git a/include/linux/bug.h b/include/linux/bug.h
index fe5916550da8..f639bd0122f3 100644
--- a/include/linux/bug.h
+++ b/include/linux/bug.h
@@ -47,6 +47,11 @@ void generic_bug_clear_once(void);
 
 #else	/* !CONFIG_GENERIC_BUG */
 
+static inline void *find_bug(unsigned long bugaddr)
+{
+	return NULL;
+}
+
 static inline enum bug_trap_type report_bug(unsigned long bug_addr,
 					    struct pt_regs *regs)
 {
-- 
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