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authorSteven Rostedt <srostedt@redhat.com>2009-02-26 23:55:58 -0500
committerSteven Rostedt <srostedt@redhat.com>2009-02-26 23:55:58 -0500
commitd8e83d26b5ab3b31ee0ff6d093a2627707a1e221 (patch)
treea8a24753ca24db4f3dd9bb887962e4cdcffac314 /kernel
parent577b785f55168d5acb3d123ba41bfe8d7981e044 (diff)
tracing: add protection around open use of current_tracer
Impact: fix to possible race conditions There's some uses of current_tracer that is not protected by the trace_types_lock. There is a small chance that a sysadmin changes the tracer while the current_tracer is being referenced. If the race is hit, it is unlikely to cause any harm since the tracers are constant and are not freed. But some strang side effects may occur. Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Diffstat (limited to 'kernel')
-rw-r--r--kernel/trace/trace.c20
1 files changed, 14 insertions, 6 deletions
diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index 485c6e7f446..6c89ec6cbd4 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -2024,12 +2024,12 @@ static ssize_t
tracing_trace_options_read(struct file *filp, char __user *ubuf,
size_t cnt, loff_t *ppos)
{
- int i;
+ struct tracer_opt *trace_opts;
+ u32 tracer_flags;
+ int len = 0;
char *buf;
int r = 0;
- int len = 0;
- u32 tracer_flags = current_trace->flags->val;
- struct tracer_opt *trace_opts = current_trace->flags->opts;
+ int i;
/* calculate max size */
@@ -2038,6 +2038,10 @@ tracing_trace_options_read(struct file *filp, char __user *ubuf,
len += 3; /* "no" and space */
}
+ mutex_lock(&trace_types_lock);
+ tracer_flags = current_trace->flags->val;
+ trace_opts = current_trace->flags->opts;
+
/*
* Increase the size with names of options specific
* of the current tracer.
@@ -2049,8 +2053,10 @@ tracing_trace_options_read(struct file *filp, char __user *ubuf,
/* +2 for \n and \0 */
buf = kmalloc(len + 2, GFP_KERNEL);
- if (!buf)
+ if (!buf) {
+ mutex_unlock(&trace_types_lock);
return -ENOMEM;
+ }
for (i = 0; trace_options[i]; i++) {
if (trace_flags & (1 << i))
@@ -2067,6 +2073,7 @@ tracing_trace_options_read(struct file *filp, char __user *ubuf,
r += sprintf(buf + r, "no%s ",
trace_opts[i].name);
}
+ mutex_unlock(&trace_types_lock);
r += sprintf(buf + r, "\n");
WARN_ON(r >= len + 2);
@@ -2074,7 +2081,6 @@ tracing_trace_options_read(struct file *filp, char __user *ubuf,
r = simple_read_from_buffer(ubuf, cnt, ppos, buf, r);
kfree(buf);
-
return r;
}
@@ -2149,7 +2155,9 @@ 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);
ret = set_tracer_option(current_trace, cmp, neg);
+ mutex_unlock(&trace_types_lock);
if (ret)
return ret;
}