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Message-Id: <20210208145820.945240185@linuxfoundation.org>
Date: Mon, 8 Feb 2021 16:00:50 +0100
From: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To: linux-kernel@...r.kernel.org
Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
stable@...r.kernel.org,
"Peter Zijlstra (Intel)" <peterz@...radead.org>,
Alexey Kardashevskiy <aik@...abs.ru>,
"Steven Rostedt (VMware)" <rostedt@...dmis.org>
Subject: [PATCH 5.10 063/120] tracepoint: Fix race between tracing and removing tracepoint
From: Alexey Kardashevskiy <aik@...abs.ru>
commit c8b186a8d54d7e12d28e9f9686cb00ff18fc2ab2 upstream.
When executing a tracepoint, the tracepoint's func is dereferenced twice -
in __DO_TRACE() (where the returned pointer is checked) and later on in
__traceiter_##_name where the returned pointer is dereferenced without
checking which leads to races against tracepoint_removal_sync() and
crashes.
This adds a check before referencing the pointer in tracepoint_ptr_deref.
Link: https://lkml.kernel.org/r/20210202072326.120557-1-aik@ozlabs.ru
Cc: stable@...r.kernel.org
Fixes: d25e37d89dd2f ("tracepoint: Optimize using static_call()")
Acked-by: Peter Zijlstra (Intel) <peterz@...radead.org>
Signed-off-by: Alexey Kardashevskiy <aik@...abs.ru>
Signed-off-by: Steven Rostedt (VMware) <rostedt@...dmis.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
include/linux/tracepoint.h | 12 +++++++-----
1 file changed, 7 insertions(+), 5 deletions(-)
--- a/include/linux/tracepoint.h
+++ b/include/linux/tracepoint.h
@@ -307,11 +307,13 @@ static inline struct tracepoint *tracepo
\
it_func_ptr = \
rcu_dereference_raw((&__tracepoint_##_name)->funcs); \
- do { \
- it_func = (it_func_ptr)->func; \
- __data = (it_func_ptr)->data; \
- ((void(*)(void *, proto))(it_func))(__data, args); \
- } while ((++it_func_ptr)->func); \
+ if (it_func_ptr) { \
+ do { \
+ it_func = (it_func_ptr)->func; \
+ __data = (it_func_ptr)->data; \
+ ((void(*)(void *, proto))(it_func))(__data, args); \
+ } while ((++it_func_ptr)->func); \
+ } \
return 0; \
} \
DEFINE_STATIC_CALL(tp_func_##_name, __traceiter_##_name);
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