Merge remote-tracking branch 'rt-stable/v4.9-rt' into linux-linaro-lsk-v4.9-rtlsk-v4.9-18.03-rt

1 files changed, 5 insertions, 13 deletions

diff --git a/fs/proc/kcore.c b/fs/proc/kcore.c
index 5c89a07e3d7f..df7e07986ead 100644
--- a/fs/proc/kcore.c
+++ b/fs/proc/kcore.c
@@ -507,23 +507,15 @@ read_kcore(struct file *file, char __user *buffer, size_t buflen, loff_t *fpos)
 				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 {