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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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