Re: [PATCH v3] perf riscv: Add perf_regs_load and enable the dwarf unwind test

[sashiko-bot@kernel.org]

Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:
- [Medium] perf: NULL pointer dereference in test__arch_unwind_sample() on OOM
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commit 5845b516a9f1970f694021ec56b60a02bd3f3b49
Author: Chen Pei <cp0613@linux.alibaba.com>

perf riscv: Add perf_regs_load and enable the dwarf unwind test

This commit adds perf_regs_load() and an architecture-specific unwind
sample helper for RISC-V. It also wires RISC-V into the test gates to
enable the DWARF unwind test on this architecture.

> diff --git a/tools/perf/arch/riscv/tests/dwarf-unwind.c b/tools/perf/arch/riscv/tests/dwarf-unwind.c
> new file mode 100644
> index 0000000000000..fe0c32ea0e05a
> --- /dev/null
> +++ b/tools/perf/arch/riscv/tests/dwarf-unwind.c

[ ... ]

> +int test__arch_unwind_sample(struct perf_sample *sample,
> +		struct thread *thread)
> +{
> +	struct regs_dump *regs = perf_sample__user_regs(sample);
> +	u64 *buf;
> +
> +	buf = calloc(PERF_REGS_MAX, sizeof(u64));
> +	if (!buf) {
> +		pr_debug("failed to allocate sample uregs data\n");
> +		return -1;
> +	}
> +
> +	perf_regs_load(buf);
> +	regs->abi  = PERF_SAMPLE_REGS_ABI;

[Severity: Medium]
Is it possible for perf_sample__user_regs() to return a NULL pointer?

If memory allocation fails during perf_sample__user_regs(), it returns NULL.
Since the subsequent calloc() for buf may still succeed, could this lead to an
unconditional NULL pointer dereference when assigning regs->abi?

Would it be better to verify that regs is not NULL before attempting to 
assign values to its fields?

> +	regs->regs = buf;
> +	regs->mask = PERF_REGS_MASK;
> +
> +	return sample_ustack(sample, thread, buf);
> +}

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Sashiko AI review · https://sashiko.dev/#/patchset/20260916084626.1166-1-cp0613@linux.alibaba.com?part=1