Messages in this thread | | | From | "chenjun (AM)" <> | Subject | Re: [PATCH] arm64/smp: check !ipi_desc[i] in arch_show_interrupts | Date | Wed, 15 Jun 2022 12:03:17 +0000 |
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在 2022/6/9 23:20, Will Deacon 写道: > 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?
Yee, that is what I do at first. But I noticed that:
void __init set_smp_ipi_range(int ipi_base, int n) for (i = 0; i < nr_ipi; i++) { err = request_percpu_irq(ipi_base + i, ipi_handler, "IPI", &cpu_number); WARN_ON(err); ipi_desc[i] = irq_to_desc(ipi_base + i);
If request_percpu_irq return a error, I not sure if ipi_desc[i] makes sense.
> > Will >
-- Regards Chen Jun
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