From 7af29141a31a2a2350589471c8979ff5f22fb9b7 Mon Sep 17 00:00:00 2001 From: Daniel Latypov Date: Fri, 5 Feb 2021 16:08:54 -0800 Subject: [PATCH] kunit: tool: fix unintentional statefulness in run_kernel() This is a bug that has been present since the first version of this code. Using [] as a default parameter is dangerous, since it's mutable. Example using the REPL: >>> def bad(param = []): ... param.append(len(param)) ... print(param) ... >>> bad() [0] >>> bad() [0, 1] This wasn't a concern in the past since it would just keep appending the same values to it. E.g. before, `args` would just grow in size like: [mem=1G', 'console=tty'] [mem=1G', 'console=tty', mem=1G', 'console=tty'] But with now filter_glob, this is more dangerous, e.g. run_kernel(filter_glob='my-test*') # default modified here run_kernel() # filter_glob still applies here! That earlier `filter_glob` will affect all subsequent calls that don't specify `args`. Note: currently the kunit tool only calls run_kernel() at most once, so it's not possible to trigger any negative side-effects right now. Fixes: 6ebf5866f2e8 ("kunit: tool: add Python wrappers for running KUnit tests") Signed-off-by: Daniel Latypov Reviewed-by: Brendan Higgins Signed-off-by: Shuah Khan --- tools/testing/kunit/kunit_kernel.py | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/tools/testing/kunit/kunit_kernel.py b/tools/testing/kunit/kunit_kernel.py index 71a5f5c1750b..f309a33256cd 100644 --- a/tools/testing/kunit/kunit_kernel.py +++ b/tools/testing/kunit/kunit_kernel.py @@ -203,7 +203,9 @@ class LinuxSourceTree(object): return False return self.validate_config(build_dir) - def run_kernel(self, args=[], build_dir='', filter_glob='', timeout=None) -> Iterator[str]: + def run_kernel(self, args=None, build_dir='', filter_glob='', timeout=None) -> Iterator[str]: + if not args: + args = [] args.extend(['mem=1G', 'console=tty']) if filter_glob: args.append('kunit.filter_glob='+filter_glob)