[PATCH v1] ld: fix segfault when linker script is not found

[Jan Beulich]

On 04.09.2025 17:19, Matthieu Longo wrote:
> ld previously crashed with a segmentation fault if the specified linker
> script could not be found. Surprisingly, ldfile_find_command_file() has
> never covered the very common case where an invalid filename was set.

Imo that's not a correct way to put it. You may want to take a look at the
2.40 variant of the function, where everything was still fine afaics. It
was a later addition which wasn't done as carefully as would have been
needed. (The same change also looks to have introduced a UBSAN issue, in
that struct script_name_list has an array-of-1-element field instead of a
flexible array member.)

> --- /dev/null
> +++ b/ld/testsuite/ld-scripts/linker-script-not-found.d
> @@ -0,0 +1,3 @@
> +#source: default-script.s
> +#ld: -T misspelled.ld
> +#error: cannot open linker script file misspelled\.ld: No such file or directory$

Everything up to the latter colon is fine, but can we really expect the
potentially libc-provided error message to exactly match "No such file or
directory"? (I'm not even entirely certain whether ENOENT is the only
possible errno value that can come back here.)

Jan