Re: [PATCH bpf-next v5 10/10] selftests/bpf: add tests to validate KASAN on JIT programs

[sashiko-bot@kernel.org]

Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:
- [Low] Infinite loop in `read_kernel_logs` if `read()` returns 0.
--

--- Patch [10]: [PATCH bpf-next v5 10/10] selftests/bpf: add tests to validate KASAN on JIT programs ---
commit f689181d893dcf7bbac97d28845dc342a1fe71e5
Author: Alexis Lothoré (eBPF Foundation) <alexis.lothore@bootlin.com>

selftests/bpf: add tests to validate KASAN on JIT programs

This commit adds a basic KASAN test runner that loads and runs BPF programs
designed to trigger memory management bugs. The tests capture kernel logs to
verify that the expected KASAN splats are emitted, ensuring the JIT compiler
has correctly inserted KASAN instrumentation.

> diff --git a/tools/testing/selftests/bpf/prog_tests/kasan.c b/tools/testing/selftests/bpf/prog_tests/kasan.c
> new file mode 100644
> index 0000000000000..2bc545e962595
> --- /dev/null
> +++ b/tools/testing/selftests/bpf/prog_tests/kasan.c
> @@ -0,0 +1,430 @@
[ ... ]
> +static int read_kernel_logs(int fd, char *buf, size_t max_len)
> +{
> +	size_t total = 0;
> +	ssize_t n;
> +
> +	buf[0] = '\0';
> +	while (1) {
> +		char *msg, *eol;
> +		size_t len;
> +
> +		n = read(fd, record, sizeof(record) - 1);
> +		if (n < 0) {
> +			if (errno == EAGAIN)
> +				break;
> +			return n;
> +		}
> +		record[n] = '\0';
> +
> +		/*
> +		 * Each kmsg record starts with some metadata, separated
> +		 * from the actual content by a semi-colon
> +		 */
> +		msg = strchr(record, ';');
> +		if (!msg)
> +			continue;

[Severity: Low]
Will this loop indefinitely if read() returns 0? 

If n == 0, record is null-terminated at index 0, making strchr() return NULL.
The continue statement then restarts the loop, causing read() to be called
again. While /dev/kmsg typically returns -EAGAIN when no data is available,
should an unexpected 0 return from read() be explicitly handled to prevent a
potential infinite loop?

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/20260709-kasan-v5-0-1c64af8e4e1e@bootlin.com?part=10