From: sboyd@codeaurora•org (Stephen Boyd)
To: linux-arm-kernel@lists•infradead.org
Subject: [PATCH] ARM: poison_init_mem: fixed underflow in loop
Date: Wed, 20 Feb 2013 13:56:51 -0800 [thread overview]
Message-ID: <512546A3.5010308@codeaurora.org> (raw)
In-Reply-To: <1361361175-26600-1-git-send-email-enrico.scholz@sigma-chemnitz.de>
On 2/20/2013 3:52 AM, Enrico Scholz wrote:
> When initmemory ends at an odd address, the loop variable in
> poison_init_mem() will underflow which causes overriding of valid
> memory. Such situations are not a theoretical issue only but
> exist in practice:
>
> | [ 0.000000] .init : 0xc0634000 - 0xc0c215ab (6070 kB)
>
> Patch makes a simple division instead of DIV_ROUND_UP() because latter
> can override some bytes after .init.
>
> Signed-off-by: Enrico Scholz <enrico.scholz@sigma-chemnitz•de>
> ---
> arch/arm/mm/init.c | 3 ++-
> 1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/arch/arm/mm/init.c b/arch/arm/mm/init.c
> index ad722f1..c431a2d 100644
> --- a/arch/arm/mm/init.c
> +++ b/arch/arm/mm/init.c
> @@ -449,7 +449,8 @@ static inline int free_area(unsigned long pfn, unsigned long end, char *s)
> static inline void poison_init_mem(void *s, size_t count)
> {
> u32 *p = (u32 *)s;
> - for (; count != 0; count -= 4)
> + count /= sizeof(*p);
> + for (; count != 0; count--)
> *p++ = 0xe7fddef0;
> }
>
Sigh. I really screwed that up badly. I wonder if we should instead
PAGE_ALIGN() the end address similar to what we're doing for the initrd
and then put a BUG_ON() inside poison_init_mem() that catches none page
aligned sizes.
--
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prev parent reply other threads:[~2013-02-20 21:56 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-02-20 11:52 [PATCH] ARM: poison_init_mem: fixed underflow in loop Enrico Scholz
2013-02-20 21:56 ` Stephen Boyd [this message]
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