Re: [PATCH bpf-next 5/5] selftests/bpf: add loader_load_fd tests

Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:
- [Medium] Unchecked pointer returns from libelf functions in `create_loader_elf` will cause a SIGSEGV upon allocation failure.
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--- Patch [5]: [PATCH bpf-next 5/5] selftests/bpf: add loader_load_fd tests ---
commit b9a0b98c13acbc44d106f86733ac4cdd18481ce7
Author: Thiébaud Weksteen <[email protected]>

selftests/bpf: add loader_load_fd tests

This commit adds user-space selftests for the BPF_LOADER_LOAD_FD command.
The test ELF is generated based on the existing light skeleton generator,
using an awk script to extract the loader program and map.

> diff --git a/tools/testing/selftests/bpf/prog_tests/loader_load_fd.c b/tools/testing/selftests/bpf/prog_tests/loader_load_fd.c
> new file mode 100644
> index 0000000000000..ab971662dd047
> --- /dev/null
> +++ b/tools/testing/selftests/bpf/prog_tests/loader_load_fd.c
[ ... ]
> +	ehdr->e_ident[EI_VERSION] = EV_CURRENT;
> +	ehdr->e_machine = EM_BPF;
> +	ehdr->e_type = ET_REL;
> +	ehdr->e_version = EV_CURRENT;
> +
> +	shstr_scn = elf_newscn(elf);
> +	shstr_shdr = elf64_getshdr(shstr_scn);
> +	shstr_shdr->sh_name = shstr_off;
> +	shstr_shdr->sh_type = SHT_STRTAB;
> +	shstr_shdr->sh_flags = 0;
> +
> +	shstr_data = elf_newdata(shstr_scn);
> +	shstr_data->d_buf = shstrtab;

[Severity: Medium]
Could this crash the test runner if libelf fails to allocate memory?

Earlier in create_loader_elf(), ASSERT_OK_PTR is used to check the return
values of elf_begin() and elf64_newehdr(). However, the pointers returned
by elf_newscn(), elf64_getshdr(), and elf_newdata() are dereferenced here
without prior validation.

If these functions return NULL, the test will abort with a segmentation
fault, preventing subsequent tests from running. This pattern also appears
to be repeated for the .prog, .map, and license sections below.

Would it be better to add ASSERT_OK_PTR checks for these allocations?

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Sashiko AI review · https://sashiko.dev/#/patchset/[email protected]?part=5