3.2-stable review patch. If anyone has any objections, please let me know.
------------------ From: "Steven Rostedt (Red Hat)" <[email protected]> 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. Signed-off-by: Steven Rostedt <[email protected]> [bwh: Backported to 3.2: also move failure return in tracing_trace_options_write() after unlocking] Signed-off-by: Ben Hutchings <[email protected]> --- --- a/kernel/trace/trace.c +++ b/kernel/trace/trace.c @@ -2661,7 +2661,7 @@ 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)) @@ -2678,6 +2678,8 @@ 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); @@ -2686,13 +2688,13 @@ 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; @@ -4379,7 +4381,10 @@ 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; -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
