kexec: return -EFAULT on copy_to_user() failures

copy_to/from_user() returns the number of bytes remaining to be copied.
It never returns a negative value.  The correct return code is -EFAULT and
not -EIO.

All the callers check for non-zero returns so that's Ok, but the return
code is passed to the user so we should fix this.

Signed-off-by: Dan Carpenter <error27@gmail.com>
Cc: Hidetoshi Seto <seto.hidetoshi@jp.fujitsu.com>
Cc: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Simon Kagstrom <simon.kagstrom@netinsight.net>
Acked-by: WANG Cong <xiyou.wangcong@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 5 insertions, 3 deletions

diff --git a/kernel/kexec.c b/kernel/kexec.c
index 131b1703936f..c0613f7d6730 100644
--- a/kernel/kexec.c
+++ b/kernel/kexec.c
@@ -151,8 +151,10 @@ static int do_kimage_alloc(struct kimage **rimage, unsigned long entry,
         image->nr_segments = nr_segments;
         segment_bytes = nr_segments * sizeof(*segments);
         result = copy_from_user(image->segment, segments, segment_bytes);
-        if (result)
+        if (result) {
+                result = -EFAULT;
                 goto out;
+        }
 
         /*
          * Verify we have good destination addresses.  The caller is
@@ -827,7 +829,7 @@ static int kimage_load_normal_segment(struct kimage *image,
                 result = copy_from_user(ptr, buf, uchunk);
                 kunmap(page);
                 if (result) {
-                        result = (result < 0) ? result : -EIO;
+                        result = -EFAULT;
                         goto out;
                 }
                 ubytes -= uchunk;
@@ -882,7 +884,7 @@ static int kimage_load_crash_segment(struct kimage *image,
                 kexec_flush_icache_page(page);
                 kunmap(page);
                 if (result) {
-                        result = (result < 0) ? result : -EIO;
+                        result = -EFAULT;
                         goto out;
                 }
                 ubytes -= uchunk;