1 files changed, 38 insertions, 0 deletions

diff --git a/fs/exec.c b/fs/exec.c
index 828dd2461d6b..03278c984ba0 100644
--- a/fs/exec.c
+++ b/fs/exec.c
@@ -2014,3 +2014,41 @@ fail_creds:
 fail:
         return;
 }
+
+/*
+ * Core dumping helper functions.  These are the only things you should
+ * do on a core-file: use only these functions to write out all the
+ * necessary info.
+ */
+int dump_write(struct file *file, const void *addr, int nr)
+{
+        return access_ok(VERIFY_READ, addr, nr) && file->f_op->write(file, addr, nr, &file->f_pos) == nr;
+}
+
+int dump_seek(struct file *file, loff_t off)
+{
+        int ret = 1;
+
+        if (file->f_op->llseek && file->f_op->llseek != no_llseek) {
+                if (file->f_op->llseek(file, off, SEEK_CUR) < 0)
+                        return 0;
+        } else {
+                char *buf = (char *)get_zeroed_page(GFP_KERNEL);
+
+                if (!buf)
+                        return 0;
+                while (off > 0) {
+                        unsigned long n = off;
+
+                        if (n > PAGE_SIZE)
+                                n = PAGE_SIZE;
+                        if (!dump_write(file, buf, n)) {
+                                ret = 0;
+                                break;
+                        }
+                        off -= n;
+                }
+                free_page((unsigned long)buf);
+        }
+        return ret;
+}