From: Kees Cook <keescook@chromium.org>
To: Michael Ellerman <mpe@ellerman.id.au>
Cc: Arnd Bergmann <arnd@arndb.de>, Anatolij Gustschin <agust@denx.de>,
Benjamin Herrenschmidt <benh@kernel.crashing.org>,
Paul Mackerras <paulus@samba.org>,
linux-kernel@vger.kernel.org, linuxppc-dev@lists.ozlabs.org
Subject: [PATCH v2] powerpc: mpc5200: Remove VLA usage
Date: Mon, 2 Jul 2018 08:56:21 -0700 [thread overview]
Message-ID: <20180702155621.GA16047@beast> (raw)
In the quest to remove all stack VLA usage from the kernel[1], this
switches to using a stack size large enough for the saved routine and
adds a sanity check making sure the routine doesn't overflow into the
0x600 exception handler.
[1] https://lkml.kernel.org/r/CA+55aFzCG-zNmZwX4A2FQpadafLfEzK6CC=qPXydAacU1RqZWA@mail.gmail.com
Signed-off-by: Kees Cook <keescook@chromium.org>
Reviewed-by: Arnd Bergmann <arnd@arndb.de>
---
v2: use "0x600-0x500" for size calculation to illustrate handler sizes
---
arch/powerpc/platforms/52xx/mpc52xx_pm.c | 5 ++++-
1 file changed, 4 insertions(+), 1 deletion(-)
diff --git a/arch/powerpc/platforms/52xx/mpc52xx_pm.c b/arch/powerpc/platforms/52xx/mpc52xx_pm.c
index 31d3515672f3..b1d208ded981 100644
--- a/arch/powerpc/platforms/52xx/mpc52xx_pm.c
+++ b/arch/powerpc/platforms/52xx/mpc52xx_pm.c
@@ -117,7 +117,10 @@ int mpc52xx_pm_enter(suspend_state_t state)
u32 intr_main_mask;
void __iomem * irq_0x500 = (void __iomem *)CONFIG_KERNEL_START + 0x500;
unsigned long irq_0x500_stop = (unsigned long)irq_0x500 + mpc52xx_ds_cached_size;
- char saved_0x500[mpc52xx_ds_cached_size];
+ char saved_0x500[0x600-0x500];
+
+ if (WARN_ON(mpc52xx_ds_cached_size > sizeof(saved_0x500)))
+ return -ENOMEM;
/* disable all interrupts in PIC */
intr_main_mask = in_be32(&intr->main_mask);
--
2.17.1
--
Kees Cook
Pixel Security
next reply other threads:[~2018-07-02 15:56 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-07-02 15:56 Kees Cook [this message]
2018-07-11 13:24 ` [v2] powerpc: mpc5200: Remove VLA usage Michael Ellerman
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