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SubjectRe: [PATCH] ARM: Ignore memory tags with invalid data
On Mon, Jan 21, 2008 at 10:05:56PM -0600, Corey Minyard wrote:
> From: Corey Minyard <minyard@acm.org>
>
> The DNS-323 system has several bogus memory entries in the tag table,
> and it caused the system to crash at startup. Ignore tag entries that
> are obviously bogus.

This should have gone to the linux-arm-kernel mailing list as well,
so that all the people interested in ARM can see it as soon as
possible. See linux-arm-kernel@lists.arm.linux.org.uk

The only suggestion I could think of would to be change to having
an check_tag_mem32() function, or put each check on its own line
to make it easier to read what each check is doing.

ie:
if (meminfo.nr_banks >= NR_BANKS ||
tag->u.mem.size & ~PAGE_MASK || /* size is unaligned */
tag->u.mem.size == 0 || /* no memory here */
tag->u.mem.start & ~PAGE_MASK) /* start is unaligned */
{
(even without the comments it makes it easier to see what each test
is.

> Signed-off-by: Corey Minyard <minyard@acm.org>
> ---
> arch/arm/kernel/setup.c | 7 ++++++-
> 1 files changed, 6 insertions(+), 1 deletions(-)
>
> diff --git a/arch/arm/kernel/setup.c b/arch/arm/kernel/setup.c
> index bf56eb3..dfdb469 100644
> --- a/arch/arm/kernel/setup.c
> +++ b/arch/arm/kernel/setup.c
> @@ -630,7 +630,12 @@ __tagtable(ATAG_CORE, parse_tag_core);
>
> static int __init parse_tag_mem32(const struct tag *tag)
> {
> - if (meminfo.nr_banks >= NR_BANKS) {
> + /*
> + * Make sure that the memory size is non-zero, page aligned,
> + * and that it doesn't overflow the meminfo table.
> + */
> + if (meminfo.nr_banks >= NR_BANKS || tag->u.mem.size & ~PAGE_MASK ||
> + tag->u.mem.size == 0 || tag->u.mem.start & ~PAGE_MASK) {
> printk(KERN_WARNING
> "Ignoring memory bank 0x%08x size %dKB\n",
> tag->u.mem.start, tag->u.mem.size / 1024);
> --
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--
Ben (ben@fluff.org, http://www.fluff.org/)

'a smiley only costs 4 bytes'


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