Messages in this thread Patch in this message | | | Date | Thu, 9 Jun 2022 16:20:03 +0100 | From | Will Deacon <> | Subject | Re: [PATCH] arm64/smp: check !ipi_desc[i] in arch_show_interrupts |
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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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