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SubjectRe: [PATCH 1/3] extend get/setrlimit to support setting rlimits external to a process (v3)
Neil Horman wrote:
> +static ssize_t proc_pid_limit_write(struct file *file, const char __user *buf,
> + size_t count, loff_t *ppos)
> +{
> + char *buffer;
> + char *element, *vmc, *vmm;
> + struct rlimit new_rlim;
> + unsigned long flags;
> + int i;
> + int index = -1;
> + size_t wcount = 0;
> + struct task_struct *task = get_proc_task(file->f_path.dentry->d_inode);
> +
> +
> + if (*ppos != 0)
> + goto out;
> +
> + if (count > 128)
> + goto out;

Shouldn't proc_pid_limit_write return 0 or some error in this case?
Right now it silently fails...

> + buffer = kzalloc(128, GFP_KERNEL);
> +
> + if (!buffer)
> + goto out;
> +
> + element = kzalloc(sizeof(buffer), GFP_KERNEL);
> + vmc = kzalloc(sizeof(buffer), GFP_KERNEL);
> + vmm = kzalloc(sizeof(buffer), GFP_KERNEL);
> +
> + if (!element || !vmm || !vmc)
> + goto out_free;
> +
> + wcount = count - copy_from_user(buffer, buf, count);
> + if (wcount < count)
> + goto out_free;
> +
> + i = sscanf(buffer, "%s %s %s", element, vmc, vmm);
> +
> + if (i < 3)
> + goto out_free;
> +
> + for (i = 0; i <= strlen(element); i++)
> + element[i] = tolower(element[i]);
> +
> + if (!strncmp(vmc, "unlimited", 9))
> + new_rlim.rlim_cur = RLIM_INFINITY;
> + else
> + new_rlim.rlim_cur = simple_strtoull(vmc, NULL, 10);
> +
> + if (!strncmp(vmm, "unlimited", 9))
> + new_rlim.rlim_max = RLIM_INFINITY;
> + else
> + new_rlim.rlim_max = simple_strtoull(vmm, NULL, 10);
> +
> + for (i = 0; i < RLIM_NLIMITS; i++) {
> + if ((lnames[i].match) &&
> + !strncmp(element, lnames[i].match,
> + strlen(lnames[i].match))) {
> + index = i;
> + break;
> + }
> }
>
> + if (!lock_task_sighand(task, &flags))
> + goto out_free;
> +
> + if ((index >= 0) && (index < RLIM_NLIMITS))
> + do_setrlimit(index, &new_rlim, task);

Another 2 silent failures:
- when user passed wrong name
- when do_setrlimit failed

> +
> + unlock_task_sighand(task, &flags);
> +
> +out_free:
> + kfree(element);
> + kfree(vmc);
> + kfree(vmm);
> + kfree(buffer);
> +out:
> + *ppos += count;
> + put_task_struct(task);
> return count;
> }
>


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