Merge tag 'mips_fixes_4.16_2' of git://git.kernel.org/pub/scm/linux/kernel/git/jhogan...

[linux.git] / fs / proc / kcore.c

diff --git a/fs/proc/kcore.c b/fs/proc/kcore.c
index 4bc85cb8be6a2f119520b6f8e279604074420eca..d1e82761de813abb95af0faac99194dba5821538 100644 (file)
--- a/fs/proc/kcore.c
+++ b/fs/proc/kcore.c
@@ -510,25 +510,21 @@ read_kcore(struct file *file, char __user *buffer, size_t buflen, loff_t *fpos)
                        /* we have to zero-fill user buffer even if no read */
                        if (copy_to_user(buffer, buf, tsz))
                                return -EFAULT;
+               } else if (m->type == KCORE_USER) {
+                       /* User page is handled prior to normal kernel page: */
+                       if (copy_to_user(buffer, (char *)start, tsz))
+                               return -EFAULT;
                } else {
                        if (kern_addr_valid(start)) {
-                               unsigned long n;
-
                                /*
                                 * Using bounce buffer to bypass the
                                 * hardened user copy kernel text checks.
                                 */
-                               memcpy(buf, (char *) start, tsz);
-                               n = copy_to_user(buffer, buf, tsz);
-                               /*
-                                * We cannot distinguish between fault on source
-                                * and fault on destination. When this happens
-                                * we clear too and hope it will trigger the
-                                * EFAULT again.
-                                */
-                               if (n) { 
-                                       if (clear_user(buffer + tsz - n,
-                                                               n))
+                               if (probe_kernel_read(buf, (void *) start, tsz)) {
+                                       if (clear_user(buffer, tsz))
+                                               return -EFAULT;
+                               } else {
+                                       if (copy_to_user(buffer, buf, tsz))
                                                return -EFAULT;
                                }
                        } else {