This is a note to let you know that I've just added the patch titled
tracing: Protect tracer flags with trace_types_lock
to the 3.4-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
tracing-protect-tracer-flags-with-trace_types_lock.patch
and it can be found in the queue-3.4 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From 69d34da2984c95b33ea21518227e1f9470f11d95 Mon Sep 17 00:00:00 2001
From: "Steven Rostedt (Red Hat)" <rostedt@xxxxxxxxxxx>
Date: Thu, 14 Mar 2013 13:50:56 -0400
Subject: tracing: Protect tracer flags with trace_types_lock
From: "Steven Rostedt (Red Hat)" <rostedt@xxxxxxxxxxx>
commit 69d34da2984c95b33ea21518227e1f9470f11d95 upstream.
Seems that the tracer flags have never been protected from
synchronous writes. Luckily, admins don't usually modify the
tracing flags via two different tasks. But if scripts were to
be used to modify them, then they could get corrupted.
Move the trace_types_lock that protects against tracers changing
to also protect the flags being set.
[Backported for 3.4, 3.0-stable. Moved return to after unlock.]
Signed-off-by: Steven Rostedt <rostedt@xxxxxxxxxxx>
Signed-off-by: Lingzhu Xiang <lxiang@xxxxxxxxxx>
Reviewed-by: CAI Qian <caiqian@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
kernel/trace/trace.c | 19 ++++++++++++-------
1 file changed, 12 insertions(+), 7 deletions(-)
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -2768,7 +2768,7 @@ tracing_trace_options_write(struct file
char buf[64];
char *cmp;
int neg = 0;
- int ret;
+ int ret = 0;
int i;
if (cnt >= sizeof(buf))
@@ -2785,6 +2785,8 @@ tracing_trace_options_write(struct file
cmp += 2;
}
+ mutex_lock(&trace_types_lock);
+
for (i = 0; trace_options[i]; i++) {
if (strcmp(cmp, trace_options[i]) == 0) {
set_tracer_flags(1 << i, !neg);
@@ -2793,13 +2795,13 @@ tracing_trace_options_write(struct file
}
/* If no option could be set, test the specific tracer options */
- if (!trace_options[i]) {
- mutex_lock(&trace_types_lock);
+ if (!trace_options[i])
ret = set_tracer_option(current_trace, cmp, neg);
- mutex_unlock(&trace_types_lock);
- if (ret)
- return ret;
- }
+
+ mutex_unlock(&trace_types_lock);
+
+ if (ret)
+ return ret;
*ppos += cnt;
@@ -4486,7 +4488,10 @@ trace_options_core_write(struct file *fi
if (val != 0 && val != 1)
return -EINVAL;
+
+ mutex_lock(&trace_types_lock);
set_tracer_flags(1 << index, val);
+ mutex_unlock(&trace_types_lock);
*ppos += cnt;
Patches currently in stable-queue which might be from rostedt@xxxxxxxxxxx are
queue-3.4/tracing-prevent-buffer-overwrite-disabled-for-latency-tracers.patch
queue-3.4/tracing-protect-tracer-flags-with-trace_types_lock.patch
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