This is a note to let you know that I have just added a patch titled
tracing: Protect tracer flags with trace_types_lock
to the linux-3.5.y-queue branch of the 3.5.y.z extended stable tree
which can be found at:
http://kernel.ubuntu.com/git?p=ubuntu/linux.git;a=shortlog;h=refs/heads/linux-3.5.y-queue
If you, or anyone else, feels it should not be added to this tree, please
reply to this email.
For more information about the 3.5.y.z tree, see
https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable
Thanks.
-Luis
------
>From e7542376f91073846ca59b0908e3fe5b77239a15 Mon Sep 17 00:00:00 2001
From: Lingzhu Xiang <lxiang@xxxxxxxxxx>
Date: Thu, 28 Mar 2013 12:26:03 +0800
Subject: [PATCH] tracing: Protect tracer flags with trace_types_lock
commit 69d34da2984c95b33ea21518227e1f9470f11d95 upstream.
Backported for 3.4, 3.0-stable. Moved return to after unlock.
From: "Steven Rostedt (Red Hat)" <rostedt@xxxxxxxxxxx>
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.
Cc: stable@xxxxxxxxxxxxxxx
Signed-off-by: Steven Rostedt <rostedt@xxxxxxxxxxx>
Signed-off-by: Lingzhu Xiang <lxiang@xxxxxxxxxx>
Reviewed-by: CAI Qian <caiqian@xxxxxxxxxx>
Signed-off-by: Luis Henriques<luis.henriques@xxxxxxxxxxxxx>
---
kernel/trace/trace.c | 19 ++++++++++++-------
1 file changed, 12 insertions(+), 7 deletions(-)
diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index 199f77b..b354405 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -2791,7 +2791,7 @@ tracing_trace_options_write(struct file *filp, const char __user *ubuf,
char buf[64];
char *cmp;
int neg = 0;
- int ret;
+ int ret = 0;
int i;
if (cnt >= sizeof(buf))
@@ -2808,6 +2808,8 @@ tracing_trace_options_write(struct file *filp, const char __user *ubuf,
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);
@@ -2816,13 +2818,13 @@ tracing_trace_options_write(struct file *filp, const char __user *ubuf,
}
/* 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;
@@ -4601,7 +4603,10 @@ trace_options_core_write(struct file *filp, const char __user *ubuf, size_t cnt,
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;
--
1.8.1.2
--
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