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    SubjectRe: [RFC v3 6/9] kmsg: add ioctl for adding and deleting kmsg* devices
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    On Monday 19 October 2015 14:58:20 Paul Osmialowski wrote:
    > +
    > +struct kmsg_cmd_buffer_add {
    > + size_t size;
    > + unsigned short mode;
    > + int minor;
    > +} __attribute__((packed));
    > +
    > +#define KMSG_IOCTL_MAGIC 0xBB
    > +
    > +/*
    >

    Try to avoid using packed unaligned data structures. Here I would
    just use __u64 and __u32 members.

    > + case KMSG_CMD_BUFFER_ADD:
    > + if (copy_from_user(&size, argp, sizeof(size)))
    > + return -EFAULT;
    > + argp += sizeof(size);
    > + if (copy_from_user(&mode, argp, sizeof(mode)))
    > + return -EFAULT;

    This is a rather unusual way to access the data. Just copy the
    entire structure to the stack.

    Arnd


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