[PATCH] ARM: fix out-of-bound access to ipi_types[]

[PATCH] ARM: fix out-of-bound access to ipi_types[]

[Masahiro Yamada]

Since commit e7273ff49acf ("ARM: 8488/1: Make IPI_CPU_BACKTRACE a
"non-secure" SGI"), IPI_CPU_BACKTRACE is assigned to SGI7.

raise_nmi() passes IPI_CPU_BACKTRACE (=7) into smp_cross_call(),
but it is above the array bound of ipi_types[].

Increase NR_IPI, and add the entry to ipi_types[].

This fixes the following GCC warning:

  CC      arch/arm/kernel/smp.o
arch/arm/kernel/smp.c: In function 'raise_nmi':
arch/arm/kernel/smp.c:522:2: warning: array subscript 7 is above array bounds of 'const char *[7]' [-Warray-bounds]
  trace_ipi_raise_rcuidle(target, ipi_types[ipinr]);
  ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
---

 arch/arm/include/asm/hardirq.h | 2 +-
 arch/arm/kernel/smp.c          | 1 +
 2 files changed, 2 insertions(+), 1 deletion(-)

diff --git a/arch/arm/include/asm/hardirq.h b/arch/arm/include/asm/hardirq.h
index cba23ea..c7e3a71 100644
--- a/arch/arm/include/asm/hardirq.h
+++ b/arch/arm/include/asm/hardirq.h
@@ -6,7 +6,7 @@
 #include <linux/threads.h>
 #include <asm/irq.h>
 
-#define NR_IPI	7
+#define NR_IPI	8
 
 typedef struct {
 	unsigned int __softirq_pending;
diff --git a/arch/arm/kernel/smp.c b/arch/arm/kernel/smp.c
index facd424..8046f9b 100644
--- a/arch/arm/kernel/smp.c
+++ b/arch/arm/kernel/smp.c
@@ -515,6 +515,7 @@ static const char *ipi_types[NR_IPI] __tracepoint_string = {
 	S(IPI_CPU_STOP, "CPU stop interrupts"),
 	S(IPI_IRQ_WORK, "IRQ work interrupts"),
 	S(IPI_COMPLETION, "completion interrupts"),
+	S(IPI_CPU_BACKTRACE, "Backtrace interrupts"),
 };
 
 static void smp_cross_call(const struct cpumask *target, unsigned int ipinr)
-- 
2.7.4

Re: [PATCH] ARM: fix out-of-bound access to ipi_types[]

[Marc Zyngier]

On Tue, 19 Mar 2019 15:52:25 +0000,
Masahiro Yamada <yamada.masahiro@socionext.com> wrote:
> 
> Since commit e7273ff49acf ("ARM: 8488/1: Make IPI_CPU_BACKTRACE a
> "non-secure" SGI"), IPI_CPU_BACKTRACE is assigned to SGI7.
> 
> raise_nmi() passes IPI_CPU_BACKTRACE (=7) into smp_cross_call(),
> but it is above the array bound of ipi_types[].
> 
> Increase NR_IPI, and add the entry to ipi_types[].
> 
> This fixes the following GCC warning:
> 
>   CC      arch/arm/kernel/smp.o
> arch/arm/kernel/smp.c: In function 'raise_nmi':
> arch/arm/kernel/smp.c:522:2: warning: array subscript 7 is above array bounds of 'const char *[7]' [-Warray-bounds]
>   trace_ipi_raise_rcuidle(target, ipi_types[ipinr]);
>   ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> 
> Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
> ---

+Arnd.

A fix for this has been around since 2016:

http://lists.infradead.org/pipermail/linux-arm-kernel/2016-February/409393.html

and reposted several times since. I don't know why it hasn't been
picked up.

	M.

-- 
Jazz is not dead, it just smell funny.