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    SubjectRe: [PATCH][2/2] fix unchecked returns from kmalloc() (in mm/slab.c)
    On Tue, Dec 07 2004, Jesper Juhl wrote:
    >
    > Problem reported by Katrina Tsipenyuk and the Fortify Software engineering
    > team in thread with subject "PROBLEM: unchecked returns from kmalloc() in
    > linux-2.6.10-rc2".
    >
    > Unfortunately I'm not very familliar with the code in question, and since
    > I didn't find a really good way to deal with a failing kmalloc() here I
    > settled for second best which is to add a BUG_ON() in case kmalloc fails.
    > This will at least crash in a sane way at the point the problem occoures
    > rather than getting strange problems at a (possibly) later time. If
    > someone who's familliar with how this code works has a better solution
    > then please step forward :) but in the mean time I think this is at least
    > a slight improvement over the current situation.
    >
    > Patch has been compile tested and boot tested and didn't blow up
    > instantly, but please review before applying.
    >
    >
    > Signed-off-by: Jesper Juhl <juhl-lkml@dif.dk>
    >
    > diff -up linux-2.6.10-rc3-bk2-orig/mm/slab.c linux-2.6.10-rc3-bk2/mm/slab.c
    > --- linux-2.6.10-rc3-bk2-orig/mm/slab.c 2004-12-06 22:24:56.000000000 +0100
    > +++ linux-2.6.10-rc3-bk2/mm/slab.c 2004-12-07 21:27:20.000000000 +0100
    > @@ -804,6 +804,7 @@ void __init kmem_cache_init(void)
    > void * ptr;
    >
    > ptr = kmalloc(sizeof(struct arraycache_init), GFP_KERNEL);
    > + BUG_ON(ptr == NULL); /* FIXME: Can a failed kmalloc be handled better? */
    > local_irq_disable();
    > BUG_ON(ac_data(&cache_cache) != &initarray_cache.cache);
    > memcpy(ptr, ac_data(&cache_cache), sizeof(struct arraycache_init));

    This is pointless, as a NULL deref on memcpy will give you the exact
    same info.

    --
    Jens Axboe

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