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    SubjectRe: [PATCH] slab: warning if total alloc size overflow
    On Tue, 14 Feb 2012, Yang Bai wrote:
    > Before, if the total alloc size is overflow,
    > we just return NULL like alloc fail. But they
    > are two different type problems. The former looks
    > more like a programming problem. So add a warning
    > here.
    >
    > Signed-off-by: Yang Bai <hamo.by@gmail.com>
    > ---
    > include/linux/slab.h | 4 +++-
    > 1 files changed, 3 insertions(+), 1 deletions(-)
    >
    > diff --git a/include/linux/slab.h b/include/linux/slab.h
    > index 573c809..5865237 100644
    > --- a/include/linux/slab.h
    > +++ b/include/linux/slab.h
    > @@ -242,8 +242,10 @@ size_t ksize(const void *);
    > */
    > static inline void *kcalloc(size_t n, size_t size, gfp_t flags)
    > {
    > - if (size != 0 && n > ULONG_MAX / size)
    > + if (size != 0 && n > ULONG_MAX / size) {
    > + WARN(1, "Alloc memory size (%lu * %lu) overflow.", n, size);
    > return NULL;
    > + }
    > return __kmalloc(n * size, flags | __GFP_ZERO);
    > }

    Did you check how much kernel text size increases? I'm pretty sure we'd
    need to wrap this with CONFIG_SLAB_OVERFLOW ifdef.

    Pekka


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