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authorSteven Rostedt (Red Hat) <rostedt@goodmis.org>2013-11-26 09:22:54 -0500
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2013-12-04 11:05:56 -0800
commit845058c554ca1265158b88933131ae2e73cdb554 (patch)
tree79c7be8d0e3ea68cb4cb2a78594b721fa16fcad3
parent102cbca66ad4cf45b92eb28bdb43e7a8fbd98937 (diff)
tracing: Allow events to have NULL strings
commit 4e58e54754dc1fec21c3a9e824bc108b05fdf46e upstream. If an TRACE_EVENT() uses __assign_str() or __get_str on a NULL pointer then the following oops will happen: BUG: unable to handle kernel NULL pointer dereference at (null) IP: [<c127a17b>] strlen+0x10/0x1a *pde = 00000000 ^M Oops: 0000 [#1] PREEMPT SMP Modules linked in: CPU: 1 PID: 0 Comm: swapper/1 Not tainted 3.13.0-rc1-test+ #2 Hardware name: /DG965MQ, BIOS MQ96510J.86A.0372.2006.0605.1717 06/05/2006^M task: f5cde9f0 ti: f5e5e000 task.ti: f5e5e000 EIP: 0060:[<c127a17b>] EFLAGS: 00210046 CPU: 1 EIP is at strlen+0x10/0x1a EAX: 00000000 EBX: c2472da8 ECX: ffffffff EDX: c2472da8 ESI: c1c5e5fc EDI: 00000000 EBP: f5e5fe84 ESP: f5e5fe80 DS: 007b ES: 007b FS: 00d8 GS: 00e0 SS: 0068 CR0: 8005003b CR2: 00000000 CR3: 01f32000 CR4: 000007d0 Stack: f5f18b90 f5e5feb8 c10687a8 0759004f 00000005 00000005 00000005 00200046 00000002 00000000 c1082a93 f56c7e28 c2472da8 c1082a93 f5e5fee4 c106bc61^M 00000000 c1082a93 00000000 00000000 00000001 00200046 00200082 00000000 Call Trace: [<c10687a8>] ftrace_raw_event_lock+0x39/0xc0 [<c1082a93>] ? ktime_get+0x29/0x69 [<c1082a93>] ? ktime_get+0x29/0x69 [<c106bc61>] lock_release+0x57/0x1a5 [<c1082a93>] ? ktime_get+0x29/0x69 [<c10824dd>] read_seqcount_begin.constprop.7+0x4d/0x75 [<c1082a93>] ? ktime_get+0x29/0x69^M [<c1082a93>] ktime_get+0x29/0x69 [<c108a46a>] __tick_nohz_idle_enter+0x1e/0x426 [<c10690e8>] ? lock_release_holdtime.part.19+0x48/0x4d [<c10bc184>] ? time_hardirqs_off+0xe/0x28 [<c1068c82>] ? trace_hardirqs_off_caller+0x3f/0xaf [<c108a8cb>] tick_nohz_idle_enter+0x59/0x62 [<c1079242>] cpu_startup_entry+0x64/0x192 [<c102299c>] start_secondary+0x277/0x27c Code: 90 89 c6 89 d0 88 c4 ac 38 e0 74 09 84 c0 75 f7 be 01 00 00 00 89 f0 48 5e 5d c3 55 89 e5 57 66 66 66 66 90 83 c9 ff 89 c7 31 c0 <f2> ae f7 d1 8d 41 ff 5f 5d c3 55 89 e5 57 66 66 66 66 90 31 ff EIP: [<c127a17b>] strlen+0x10/0x1a SS:ESP 0068:f5e5fe80 CR2: 0000000000000000 ---[ end trace 01bc47bf519ec1b2 ]--- New tracepoints have been added that have allowed for NULL pointers being assigned to strings. To fix this, change the TRACE_EVENT() code to check for NULL and if it is, it will assign "(null)" to it instead (similar to what glibc printf does). Reported-by: Shuah Khan <shuah.kh@samsung.com> Reported-by: Jovi Zhangwei <jovi.zhangwei@gmail.com> Link: http://lkml.kernel.org/r/CAGdX0WFeEuy+DtpsJzyzn0343qEEjLX97+o1VREFkUEhndC+5Q@mail.gmail.com Link: http://lkml.kernel.org/r/528D6972.9010702@samsung.com Fixes: 9cbf117662e2 ("tracing/events: provide string with undefined size support") Signed-off-by: Steven Rostedt <rostedt@goodmis.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
-rw-r--r--include/trace/ftrace.h5
1 files changed, 3 insertions, 2 deletions
diff --git a/include/trace/ftrace.h b/include/trace/ftrace.h
index 5c7ab17cbb02..712ea36067ab 100644
--- a/include/trace/ftrace.h
+++ b/include/trace/ftrace.h
@@ -372,7 +372,8 @@ ftrace_define_fields_##call(struct ftrace_event_call *event_call) \
__data_size += (len) * sizeof(type);
#undef __string
-#define __string(item, src) __dynamic_array(char, item, strlen(src) + 1)
+#define __string(item, src) __dynamic_array(char, item, \
+ strlen((src) ? (const char *)(src) : "(null)") + 1)
#undef DECLARE_EVENT_CLASS
#define DECLARE_EVENT_CLASS(call, proto, args, tstruct, assign, print) \
@@ -502,7 +503,7 @@ static inline notrace int ftrace_get_offsets_##call( \
#undef __assign_str
#define __assign_str(dst, src) \
- strcpy(__get_str(dst), src);
+ strcpy(__get_str(dst), (src) ? (const char *)(src) : "(null)");
#undef TP_fast_assign
#define TP_fast_assign(args...) args