Messages in this thread | | | Date | Tue, 05 May 2015 17:57:18 +0200 | From | Javier Martinez Canillas <> | Subject | Re: [RESEND PATCH 4/8] mfd: cros_ec: Use a zero-length array for command data |
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Hello Gwendal,
On 04/24/2015 10:29 PM, Gwendal Grignou wrote: > On Mon, Apr 6, 2015 at 9:15 AM, Javier Martinez Canillas > <javier.martinez@collabora.co.uk> wrote:
[snip]
>> >> @@ -110,17 +115,25 @@ static ssize_t ec_device_read(struct file *filp, char __user *buffer, >> static long ec_device_ioctl_xcmd(struct cros_ec_device *ec, void __user *arg) >> { >> long ret; >> - struct cros_ec_command s_cmd = { }; >> + int len; >> + struct cros_ec_command *u_cmd = arg; >> + struct cros_ec_command *s_cmd; >> + >> + len = max(u_cmd->outsize, u_cmd->insize); > It does not work, u_cmd is not accessible yet. You should do: > struct cros_ec_command u_cmd; > if (copy_from_user(&u_cmd, arg, sizeof(u_cmd))) > return -EFAULT; > len = max(u_cmd.outsize, u_cmd.insize); > >
Right, I'll change that.
>> + >> + s_cmd = kzalloc(sizeof(*s_cmd) + len, GFP_KERNEL); >> + if (!s_cmd) >> + return -ENOMEM; >> >> - if (copy_from_user(&s_cmd, arg, sizeof(s_cmd))) >> + if (copy_from_user(s_cmd, arg, sizeof(*s_cmd) + len)) > sizeof(*s_cmd) + u_cmd.outsize is good enough.
Ok.
>> return -EFAULT; >> >> - ret = cros_ec_cmd_xfer(ec, &s_cmd); >> + ret = cros_ec_cmd_xfer(ec, s_cmd); >> /* Only copy data to userland if data was received. */ >> if (ret < 0) >> return ret; >> >> - if (copy_to_user(arg, &s_cmd, sizeof(s_cmd))) >> + if (copy_to_user(arg, s_cmd, sizeof(*s_cmd) + len)) > sizeof(*s_cmd) + min(ret, u_cmd.insize) is safer
Sure.
>> return -EFAULT; >> >> return 0; > I missed this one earlier. Tools expect the number of byte read, so it should be > return ret; >
Ok, I'll change that as well.
Thanks a lot for your feedback!
Best regards, Javier
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