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tracing: Protect tracer flags with trace_types_lock
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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@vger.kernel.org
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
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Steven Rostedt (Red Hat) committed Mar 14, 2013
1 parent 740466b commit 69d34da
Showing 1 changed file with 8 additions and 4 deletions.
12 changes: 8 additions & 4 deletions kernel/trace/trace.c
Original file line number Diff line number Diff line change
Expand Up @@ -2916,6 +2916,8 @@ static int trace_set_options(char *option)
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);
Expand All @@ -2924,11 +2926,10 @@ static int trace_set_options(char *option)
}

/* 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);
}

mutex_unlock(&trace_types_lock);

return ret;
}
Expand Down Expand Up @@ -4781,7 +4782,10 @@ 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;

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