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    SubjectRe: integer overflows in kernel/relay.c
    On Wed, 08 Feb 2012 09:34:16 +0100
    Jens Axboe <axboe@kernel.dk> wrote:

    > On 02/07/2012 03:11 PM, Dan Carpenter wrote:
    > > My static checker is warning about integer overflows in kernel/relay.c
    > >
    > > relay_create_buf()
    > > 170
    > > 171 buf->padding = kmalloc(chan->n_subbufs * sizeof(size_t *), GFP_KERNEL);
    > > ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    > > This can only overflow on 32bit systems.
    >
    > Correct

    This is a relatively common problem. Converting a kzalloc() call to
    kcalloc() fixes it. But we do not have a non-zeroing version of
    kcalloc().

    Please, someone complete this patch and send it to me!


    --- a/include/linux/slab.h~a
    +++ a/include/linux/slab.h
    @@ -240,11 +240,16 @@ size_t ksize(const void *);
    * for general use, and so are not documented here. For a full list of
    * potential flags, always refer to linux/gfp.h.
    */
    -static inline void *kcalloc(size_t n, size_t size, gfp_t flags)
    +static inline void *wtf_do_i_call_this(size_t n, size_t size, gfp_t flags)
    {
    if (size != 0 && n > ULONG_MAX / size)
    return NULL;
    - return __kmalloc(n * size, flags | __GFP_ZERO);
    + return __kmalloc(n * size, flags);
    +}
    +
    +static inline void *kcalloc(size_t n, size_t size, gfp_t flags)
    +{
    + return wtf_do_i_call_this(n, size, flags | __GFP_ZERO);
    }

    #if !defined(CONFIG_NUMA) && !defined(CONFIG_SLOB)
    _


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