Re: coredump01: New core_pattern specifiers test

Hi Andrea,

On Aug 20, 2026, Andrea Cervesato wrote:
> coredump01: New core_pattern specifiers test

> 	ssize_t rval, i;
> 	int fd, elf;
>
> 	if (bytes >= 4 && !memcmp(magic, "\177ELF", 4))
> 		elf = 1;
>
> 	dprintf(fd, "exe=%s pid=%s sig=%s bytes=%lld elf=%d\n",
> 		argv[1], argv[2], argv[3], bytes, elf);

Could `elf` be initialized to zero? For short or non-ELF input the
condition does not assign it, so `dprintf()` reads an indeterminate value.
A nonzero value can make the test accept a malformed core stream as ELF.

> 	SAFE_PRCTL(PR_GET_DUMPABLE, 1, 0, 0, 0);

Should this use `PR_SET_DUMPABLE`? `PR_GET_DUMPABLE` only returns the
current state and ignores arg2, so this call does not ensure that
`abort()` can produce a core dump.

> 	/* the kernel spawns the helper asynchronously */
> 	if (TST_RETRY_FN_EXP_BACKOFF(access(res, F_OK), TST_RETVAL_EQ0, HELPER_TIMEOUT)) {
> 		tst_res(TFAIL, "%s did not report any core dump", HELPER);

Could kernels with `CONFIG_STATIC_USERMODEHELPER` be rejected with TCONF
before this check? In particular, an empty
`CONFIG_STATIC_USERMODEHELPER_PATH` intentionally disables the helper, so
this timeout reports TFAIL without testing specifier expansion.

> 	set_pattern("|%s/%s %%e %%p %%s %s/res.%%p", helper_dir, HELPER, cwd);
>
> 	len = SAFE_READLINK("/proc/self/exe", helper_dir, sizeof(helper_dir) - 1);

Could the pipe case require the initial mount namespace, or otherwise use
paths visible there? The kernel resolves and runs a `core_pattern` pipe
handler in the initial mount namespace. If LTP runs in another mount
namespace, these helper and result paths may not exist there, producing a
spurious TFAIL.

> /*
>  * Core dump collector for the piped core_pattern tested by coredump01.
>  *
>  * Avoiding the LTP API here is correct, since the kernel spawns the helper
>  * through ``call_usermodehelper()`` without the LTP IPC environment.
>  */
>
> int main(int argc, char *argv[])

Could this helper follow the LTP helper-binary convention by defining
`TST_NO_DEFAULT_MAIN` and including `tst_test.h`? The missing IPC
environment means it should avoid IPC-backed result calls, but does not
require avoiding the helper API form itself.

Verdict - Needs revision

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LTP AI Reviewer

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