linux-kernel - Re: [REPORT][next] pinctrl: pinctrl-microchip-sgpio: out-of-bounds bug in sgpio

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Date:   Wed, 3 Feb 2021 13:00:47 +0100
From:   Lars Povlsen <lars.povlsen@...rochip.com>
To:     "Gustavo A. R. Silva" <gustavoars@...nel.org>
CC:     Lars Povlsen <lars.povlsen@...rochip.com>,
        Steen Hegelund <Steen.Hegelund@...rochip.com>,
        <UNGLinuxDriver@...rochip.com>,
        Linus Walleij <linus.walleij@...aro.org>,
        <linux-arm-kernel@...ts.infradead.org>,
        <linux-gpio@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
        <linux-hardening@...r.kernel.org>
Subject: Re: [REPORT][next] pinctrl: pinctrl-microchip-sgpio: out-of-bounds bug in sgpio_clrsetbits()


Gustavo A. R. Silva writes:

> Hi,
>
> While addressing some out-of-bounds warnings, I found the following bug:
>
> drivers/pinctrl/pinctrl-microchip-sgpio.c:154:57: warning: array subscript 10 is above array bounds of ‘const u8[10]’ {aka ‘const unsigned char[10]’} [-Warray-bounds]
>
> The bug was introduced by commit be2dc859abd4 ("pinctrl: pinctrl-microchip-sgpio: Add irq support (for sparx5)"):
>
> 575         sgpio_clrsetbits(bank->priv, REG_INT_TRIGGER + SGPIO_MAX_BITS, addr.bit,
> 576                          BIT(addr.port), (!!(type & 0x2)) << addr.port);
>
> REG_INT_TRIGGER + SGPIO_MAX_BITS turns out to be 10, which is outside the boundaries
> of priv->properties->regoff[] at line 154:

Hi Gustavo!

Thanks for spotting this - the "+" is misplaced. I will submit a patch
asap.

Cheers,

---Lars

>
> 151 static inline void sgpio_clrsetbits(struct sgpio_priv *priv,
> 152                                     u32 rno, u32 off, u32 clear, u32 set)
> 153 {
> 154         u32 __iomem *reg = &priv->regs[priv->properties->regoff[rno] + off];
> 155         u32 val = readl(reg);
> 156
> 157         val &= ~clear;
> 158         val |= set;
> 159
> 160         writel(val, reg);
> 161 }
>
> because priv->properties->regoff[] is an array of MAXREG elements, with MAXREG
> representing the value of 10 in the following enum:
>
>  28 enum {
>  29         REG_INPUT_DATA,
>  30         REG_PORT_CONFIG,
>  31         REG_PORT_ENABLE,
>  32         REG_SIO_CONFIG,
>  33         REG_SIO_CLOCK,
>  34         REG_INT_POLARITY,
>  35         REG_INT_TRIGGER,
>  36         REG_INT_ACK,
>  37         REG_INT_ENABLE,
>  38         REG_INT_IDENT,
>  39         MAXREG
>  40 };
>
>  52 struct sgpio_properties {
>  53         int arch;
>  54         int flags;
>  55         u8 regoff[MAXREG];
>  56 };
>
> Thanks


-- 
Lars Povlsen,
Microchip