[PATCH v2] module: report -EFAULT on bytes remaining

Caught by smatch:
kernel/module.c:2450 copy_module_from_user() warn: maybe return -EFAULT instead of the bytes remaining?

Fix the check of copy_from_user() to report -EFAULT as was done before.

Reported-by: Fengguang Wu <redacted>
Signed-off-by: Kees Cook <redacted>
---
Should be applied on top of the finit_module syscall patches.

v2:
 - copy_from_user never returns negative, thanks to Dan Carpenter.
---
 kernel/module.c |    5 +++--
 1 files changed, 3 insertions(+), 2 deletions(-)

diff --git a/kernel/module.c b/kernel/module.c
index 0ad03c4..461e7d4 100644
--- a/kernel/module.c
+++ b/kernel/module.c

@@ -2440,9 +2440,10 @@ int copy_module_from_user(const void __user *umod, unsigned long len,
 	if (!info->hdr)
 		return -ENOMEM;
 
-	err = copy_from_user(info->hdr, umod, info->len);
-	if (err)
+	if (copy_from_user(info->hdr, umod, info->len) != 0) {
+		err = -EFAULT;
 		goto free_hdr;
+	}
 
 	err = check_info(info);
 	if (err)

-- 
1.7.0.4


-- 
Kees Cook
Chrome OS Security