Re: [PATCH v3] pager: fix crash when pager program doesn't exist
From: Jeff King <hidden>
Date: 2021-11-24 15:55:28
On Wed, Nov 24, 2021 at 11:54:09AM -0300, Enzo Matsumiya wrote:
When prepare_cmd() fails for, e.g., pager process setup, child_process_clear() frees the memory in pager_process.args, but .argv was pointed to pager_process.args.v earlier in start_command(), so it's now a dangling pointer. setup_pager() is then called a second time, from cmd_log_init_finish() in this case, and any further operations using its .argv, e.g. strvec_*, will use the dangling pointer and eventually crash. According to trivial tests, setup_pager() is not called twice if the first call is successful. This patch makes sure that pager_process is properly initialized on setup_pager(). Add a test to catch possible regressions.
Oh, good. I just replied in the separate thread suggesting this direction, but I see you had already sent this. :) This patch looks good to me. Two small nits:
quoted hunk ↗ jump to hunk
diff --git a/pager.c b/pager.c index 52f27a6765c8..d93304527d62 100644 --- a/pager.c +++ b/pager.c@@ -124,6 +124,8 @@ void setup_pager(void) setenv("GIT_PAGER_IN_USE", "true", 1); + child_process_init(&pager_process); +
You could drop the CHILD_PROCESS_INIT initializer in the declaration of pager_process now. I'm OK with keeping it, though, as a belt-and-suspenders thing. If we don't run setup_pager() at all I don't think anybody should look at it (since we won't have installed our signal/atexit cleanup handlers), but it doesn't hurt.
quoted hunk ↗ jump to hunk
diff --git a/t/t7006-pager.sh b/t/t7006-pager.sh index 0e7cf75435ec..0be9bcba49a8 100755 --- a/t/t7006-pager.sh +++ b/t/t7006-pager.sh@@ -786,4 +786,9 @@ test_expect_success TTY 'git returns SIGPIPE on propagated signals from pager' ' test_path_is_file pager-used ' +test_expect_success TTY 'handle attempt to run an invalid pager' ' + test_config pager.show invalid-pager && + test_terminal git show +'
Yep, this should trigger the bug. I agree with Eric that "non-existent" is probably more descriptive, as the key thing here is that start_command() fails immediately, rather than us piping to the broken pager. -Peff