1 files changed, 25 insertions, 24 deletions

diff --git a/fs/proc/generic.c b/fs/proc/generic.c
index b638fb500743..20e5c4509a43 100644
--- a/fs/proc/generic.c
+++ b/fs/proc/generic.c
@@ -21,6 +21,8 @@
 #include <linux/bitops.h>
 #include <asm/uaccess.h>
 
+#include "internal.h"
+
 static ssize_t proc_file_read(struct file *file, char __user *buf,
                               size_t nbytes, loff_t *ppos);
 static ssize_t proc_file_write(struct file *file, const char __user *buffer,
@@ -54,6 +56,18 @@ proc_file_read(struct file *file, char __user *buf, size_t nbytes,
         ssize_t n, count;
         char    *start;
         struct proc_dir_entry * dp;
+        unsigned long long pos;
+
+        /*
+         * Gaah, please just use "seq_file" instead. The legacy /proc
+         * interfaces cut loff_t down to off_t for reads, and ignore
+         * the offset entirely for writes..
+         */
+        pos = *ppos;
+        if (pos > MAX_NON_LFS)
+                return 0;
+        if (nbytes > MAX_NON_LFS - pos)
+                nbytes = MAX_NON_LFS - pos;
 
         dp = PDE(inode);
         if (!(page = (char*) __get_free_page(GFP_KERNEL)))
@@ -202,30 +216,17 @@ proc_file_write(struct file *file, const char __user *buffer,
 static loff_t
 proc_file_lseek(struct file *file, loff_t offset, int orig)
 {
-    lock_kernel();
-
-    switch (orig) {
-    case 0:
-        if (offset < 0)
-            goto out;
-        file->f_pos = offset;
-        unlock_kernel();
-        return(file->f_pos);
-    case 1:
-        if (offset + file->f_pos < 0)
-            goto out;
-        file->f_pos += offset;
-        unlock_kernel();
-        return(file->f_pos);
-    case 2:
-        goto out;
-    default:
-        goto out;
-    }
-
-out:
-    unlock_kernel();
-    return -EINVAL;
+        loff_t retval = -EINVAL;
+        switch (orig) {
+        case 1:
+                offset += file->f_pos;
+        /* fallthrough */
+        case 0:
+                if (offset < 0 || offset > MAX_NON_LFS)
+                        break;
+                file->f_pos = retval = offset;
+        }
+        return retval;
 }
 
 static int proc_notify_change(struct dentry *dentry, struct iattr *iattr)