From: Will Deacon <will@kernel.org>
To: Chen Jun <chenjun102@huawei.com>
Cc: linux-kernel@vger.kernel.org,
linux-arm-kernel@lists.infradead.org, catalin.marinas@arm.com,
xuqiang36@huawei.com
Subject: Re: [PATCH] arm64/smp: check !ipi_desc[i] in arch_show_interrupts
Date: Thu, 9 Jun 2022 16:20:03 +0100 [thread overview]
Message-ID: <20220609152003.GC3289@willie-the-truck> (raw)
In-Reply-To: <20220527082236.78037-1-chenjun102@huawei.com>
On Fri, May 27, 2022 at 08:22:36AM +0000, Chen Jun wrote:
> There is a potential dereferencing null pointer issue in
> arch_show_interrupts.
>
> Problem 1:
> int arch_show_interrupts(struct seq_file *p, int prec)
> for (i = 0; i < NR_IPI; i++) {
> seq_printf(p, "%10u ", irq_desc_kstat_cpu(ipi_desc[i],
> cpu));
>
> Only ipi_desc[0..nr_ipi - 1] are initialized in set_smp_ipi_range.
> and ipi_desc[nr_ipi..NR_IPI] are NULL.
> irq_desc_kstat_cpu will dereference NULL pointer.
> For now, the problem can not be triggered, because NR_IPI is always
> equal to nr_ipi.
>
> Problem 2:
> If request_percpu_irq failed in set_smp_ipi_range, ipi_desc[i]
> would be NULL.
> irq_desc_kstat_cpu will dereference NULL pointer.
>
> check !ipi_desc[i] (as arm does) to avoid the problem.
>
> Signed-off-by: Chen Jun <chenjun102@huawei.com>
> ---
> arch/arm64/kernel/smp.c | 3 +++
> 1 file changed, 3 insertions(+)
>
> diff --git a/arch/arm64/kernel/smp.c b/arch/arm64/kernel/smp.c
> index 62ed361a4376..3d54f464428b 100644
> --- a/arch/arm64/kernel/smp.c
> +++ b/arch/arm64/kernel/smp.c
> @@ -781,6 +781,9 @@ int arch_show_interrupts(struct seq_file *p, int prec)
> unsigned int cpu, i;
>
> for (i = 0; i < NR_IPI; i++) {
> + if (!ipi_desc[i])
> + continue;
Why not just use nr_ipi instead of NR_IPI?
Will
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next prev parent reply other threads:[~2022-06-09 15:21 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-05-27 8:22 [PATCH] arm64/smp: check !ipi_desc[i] in arch_show_interrupts Chen Jun
2022-06-09 15:20 ` Will Deacon [this message]
2022-06-15 12:03 ` chenjun (AM)
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