proc: convert to kstrto*()/kstrto*_from_user()

Convert from manual allocation/copy_from_user/...  to kstrto*() family
which were designed for exactly that.

One case can not be converted to kstrto*_from_user() to make code even
more simpler because of whitespace stripping, oh well...

Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 21 insertions, 49 deletions

diff --git a/fs/proc/base.c b/fs/proc/base.c
index 60c71b10eaee..b25eee4cead5 100644
--- a/fs/proc/base.c
+++ b/fs/proc/base.c
@@ -1230,10 +1230,9 @@ static ssize_t proc_loginuid_write(struct file * file, const char __user * buf,
                                    size_t count, loff_t *ppos)
 {
         struct inode * inode = file_inode(file);
-        char *page, *tmp;
-        ssize_t length;
         uid_t loginuid;
         kuid_t kloginuid;
+        int rv;
 
         rcu_read_lock();
         if (current != pid_task(proc_pid(inode), PIDTYPE_PID)) {
@@ -1242,46 +1241,28 @@ static ssize_t proc_loginuid_write(struct file * file, const char __user * buf,
         }
         rcu_read_unlock();
 
-        if (count >= PAGE_SIZE)
-                count = PAGE_SIZE - 1;
-
         if (*ppos != 0) {
                 /* No partial writes. */
                 return -EINVAL;
         }
-        page = (char*)__get_free_page(GFP_TEMPORARY);
-        if (!page)
-                return -ENOMEM;
-        length = -EFAULT;
-        if (copy_from_user(page, buf, count))
-                goto out_free_page;
 
-        page[count] = '\0';
-        loginuid = simple_strtoul(page, &tmp, 10);
-        if (tmp == page) {
-                length = -EINVAL;
-                goto out_free_page;
-
-        }
+        rv = kstrtou32_from_user(buf, count, 10, &loginuid);
+        if (rv < 0)
+                return rv;
 
         /* is userspace tring to explicitly UNSET the loginuid? */
         if (loginuid == AUDIT_UID_UNSET) {
                 kloginuid = INVALID_UID;
         } else {
                 kloginuid = make_kuid(file->f_cred->user_ns, loginuid);
-                if (!uid_valid(kloginuid)) {
-                        length = -EINVAL;
-                        goto out_free_page;
-                }
+                if (!uid_valid(kloginuid))
+                        return -EINVAL;
         }
 
-        length = audit_set_loginuid(kloginuid);
-        if (likely(length == 0))
-                length = count;
-
-out_free_page:
-        free_page((unsigned long) page);
-        return length;
+        rv = audit_set_loginuid(kloginuid);
+        if (rv < 0)
+                return rv;
+        return count;
 }
 
 static const struct file_operations proc_loginuid_operations = {
@@ -1335,8 +1316,9 @@ static ssize_t proc_fault_inject_write(struct file * file,
                         const char __user * buf, size_t count, loff_t *ppos)
 {
         struct task_struct *task;
-        char buffer[PROC_NUMBUF], *end;
+        char buffer[PROC_NUMBUF];
         int make_it_fail;
+        int rv;
 
         if (!capable(CAP_SYS_RESOURCE))
                 return -EPERM;
@@ -1345,9 +1327,9 @@ static ssize_t proc_fault_inject_write(struct file * file,
                 count = sizeof(buffer) - 1;
         if (copy_from_user(buffer, buf, count))
                 return -EFAULT;
-        make_it_fail = simple_strtol(strstrip(buffer), &end, 0);
-        if (*end)
-                return -EINVAL;
+        rv = kstrtoint(strstrip(buffer), 0, &make_it_fail);
+        if (rv < 0)
+                return rv;
         if (make_it_fail < 0 || make_it_fail > 1)
                 return -EINVAL;
 
@@ -2488,32 +2470,20 @@ static ssize_t proc_coredump_filter_write(struct file *file,
 {
         struct task_struct *task;
         struct mm_struct *mm;
-        char buffer[PROC_NUMBUF], *end;
         unsigned int val;
         int ret;
         int i;
         unsigned long mask;
 
-        ret = -EFAULT;
-        memset(buffer, 0, sizeof(buffer));
-        if (count > sizeof(buffer) - 1)
-                count = sizeof(buffer) - 1;
-        if (copy_from_user(buffer, buf, count))
-                goto out_no_task;
-
-        ret = -EINVAL;
-        val = (unsigned int)simple_strtoul(buffer, &end, 0);
-        if (*end == '\n')
-                end++;
-        if (end - buffer == 0)
-                goto out_no_task;
+        ret = kstrtouint_from_user(buf, count, 0, &val);
+        if (ret < 0)
+                return ret;
 
         ret = -ESRCH;
         task = get_proc_task(file_inode(file));
         if (!task)
                 goto out_no_task;
 
-        ret = end - buffer;
         mm = get_task_mm(task);
         if (!mm)
                 goto out_no_mm;
@@ -2529,7 +2499,9 @@ static ssize_t proc_coredump_filter_write(struct file *file,
  out_no_mm:
         put_task_struct(task);
  out_no_task:
-        return ret;
+        if (ret < 0)
+                return ret;
+        return count;
 }
 
 static const struct file_operations proc_coredump_filter_operations = {