From: Steven Rostedt <rostedt@xxxxxxxxxxx> commit 22bec11a569983f39c6061cb82279e7de9e3bdfc upstream. When the function tracing_set_tracer() switched over to using the guard() infrastructure, it did not need to save the 'ret' variable and would just return the value when an error arised, instead of setting ret and jumping to an out label. When CONFIG_TRACER_SNAPSHOT is enabled, it had code that expected the "ret" variable to be initialized to zero and had set 'ret' while holding an arch_spin_lock() (not used by guard), and then upon releasing the lock it would check 'ret' and exit if set. But because ret was only set when an error occurred while holding the locks, 'ret' would be used uninitialized if there was no error. The code in the CONFIG_TRACER_SNAPSHOT block should be self contain. Make sure 'ret' is also set when no error occurred. Cc: Mathieu Desnoyers <mathieu.desnoyers@xxxxxxxxxxxx> Link: https://lore.kernel.org/20250106111143.2f90ff65@xxxxxxxxxxxxxxxxxx Reported-by: kernel test robot <lkp@xxxxxxxxx> Reported-by: Dan Carpenter <dan.carpenter@xxxxxxxxxx> Closes: https://lore.kernel.org/r/202412271654.nJVBuwmF-lkp@xxxxxxxxx/ Fixes: d33b10c0c73ad ("tracing: Switch trace.c code over to use guard()") Signed-off-by: Steven Rostedt (Google) <rostedt@xxxxxxxxxxx> Acked-by: Masami Hiramatsu (Google) <mhiramat@xxxxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- kernel/trace/trace.c | 3 +-- 1 file changed, 1 insertion(+), 2 deletions(-) --- a/kernel/trace/trace.c +++ b/kernel/trace/trace.c @@ -6102,8 +6102,7 @@ int tracing_set_tracer(struct trace_arra if (t->use_max_tr) { local_irq_disable(); arch_spin_lock(&tr->max_lock); - if (tr->cond_snapshot) - ret = -EBUSY; + ret = tr->cond_snapshot ? -EBUSY : 0; arch_spin_unlock(&tr->max_lock); local_irq_enable(); if (ret) Patches currently in stable-queue which might be from rostedt@xxxxxxxxxxx are queue-6.13/tracing-switch-trace.c-code-over-to-use-guard.patch queue-6.13/tracing-have-the-error-of-__tracing_resize_ring_buff.patch queue-6.13/tracing-fix-using-ret-variable-in-tracing_set_tracer.patch queue-6.13/ftrace-correct-preemption-accounting-for-function-tracing.patch queue-6.13/ftrace-do-not-add-duplicate-entries-in-subops-manager-ops.patch queue-6.13/ftrace-fix-accounting-of-adding-subops-to-a-manager-ops.patch
