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    Subject[PATCH v2] comedi: integer overflow in do_insnlist_ioctl()
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    There is a potential integer overflow in do_insnlist_ioctl() if
    userspace passes in a large insnlist.n_insns. The call to kmalloc()
    would allocate a small buffer, leading to a memory corruption.

    Reported-by: Haogang Chen <haogangchen@gmail.com>
    Suggested-by: Dan Carpenter <dan.carpenter@oracle.com>
    Suggested-by: Ian Abbott <abbotti@mev.co.uk>
    Signed-off-by: Xi Wang <xi.wang@gmail.com>
    ---
    drivers/staging/comedi/comedi_fops.c | 5 +++--
    1 files changed, 3 insertions(+), 2 deletions(-)

    diff --git a/drivers/staging/comedi/comedi_fops.c b/drivers/staging/comedi/comedi_fops.c
    index 21d8c1c..df86a9e 100644
    --- a/drivers/staging/comedi/comedi_fops.c
    +++ b/drivers/staging/comedi/comedi_fops.c
    @@ -670,8 +670,9 @@ static int do_insnlist_ioctl(struct comedi_device *dev,
    goto error;
    }

    - insns =
    - kmalloc(sizeof(struct comedi_insn) * insnlist.n_insns, GFP_KERNEL);
    + if (insnlist.n_insns <= ULONG_MAX / sizeof(struct comedi_insn))
    + insns = kmalloc(sizeof(struct comedi_insn) * insnlist.n_insns,
    + GFP_KERNEL);
    if (!insns) {
    DPRINTK("kmalloc failed\n");
    ret = -ENOMEM;
    --
    1.7.5.4



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