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    SubjectRe: [PATCH] drivers/net/wimax/i2400m/fw.c fix possible double free
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    On Wed, 2010-03-17 at 05:40 -0700, Darren Jenkins wrote: 
    > On Wed, Mar 17, 2010 at 8:14 AM, David Miller <davem@davemloft.net>
    > wrote:
    >
    > > Therefore the krealloc() failure handling in this driver should NULL
    > > out i2400m->fw_hdrs and that will fix the double kfree problem as well
    > > as trap any stray references.
    >
    > Yes that is a much better Idea. Thanks for the advice.
    > It also fixes the i2400m_barker_db problem that I didn't notice before.
    >
    >
    > Fix double free on krealloc() failure by zeroing pointer

    If krealloc() fails to aallocate a new pointer, the old block is
    unmodified, so by doing this you are leaking a buffer allocation.

    I think this should be solved at the site where i2400m_zrealloc_2x() is
    called, with a

    if (result < 0) {
    kfree(i2400m->fw_hdrs);
    i2400m->fw_hdrs = NULL;
    goto error_zrealloc;
    }

    or any other better fix. I am hesitant of having zrealloc_2x free the
    original pointer because it breaks the traditional semantics that come
    along being called 'realloc' (realloc if successful, keep the original
    if not).

    Am I missing anything?


    > coverity CID: 13455
    >
    > Signed-off-by: Darren Jenkins <darrenrjenkins@gmail.com>
    > ---
    > drivers/net/wimax/i2400m/fw.c | 5 +++--
    > 1 files changed, 3 insertions(+), 2 deletions(-)
    >
    > diff --git a/drivers/net/wimax/i2400m/fw.c b/drivers/net/wimax/i2400m/fw.c
    > index 25c24f0..9f3b594 100644
    > --- a/drivers/net/wimax/i2400m/fw.c
    > +++ b/drivers/net/wimax/i2400m/fw.c
    > @@ -232,8 +232,9 @@ int i2400m_zrealloc_2x(void **ptr, size_t *_count, size_t el_size,
    > *_count = new_count;
    > *ptr = nptr;
    > return 0;
    > - } else
    > - return -ENOMEM;
    > + }
    > + *ptr = NULL;
    > + return -ENOMEM;
    > }
    >
    >





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