[lucid 1/2] floppy: ignore kernel-only members in FDRAWCMD ioctl input

[Andy Whitcroft]

From: Matthew Daley <mattd at bugfuzz.com>

Always clear out these floppy_raw_cmd struct members after copying the
entire structure from userspace so that the in-kernel version is always
valid and never left in an interdeterminate state.

Signed-off-by: Matthew Daley <mattd at bugfuzz.com>
Signed-off-by: Linus Torvalds <torvalds at linux-foundation.org>

(backported from commit ef87dbe7614341c2e7bfe8d32fcb7028cc97442c upstream)
CVE-2014-1737
BugLink: http://bugs.launchpad.net/bugs/1316729
Signed-off-by: Andy Whitcroft <apw at canonical.com>
---
 drivers/block/floppy.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/drivers/block/floppy.c b/drivers/block/floppy.c
index 5c01f74..e0022b1 100644
--- a/drivers/block/floppy.c
+++ b/drivers/block/floppy.c
@@ -3209,9 +3209,12 @@ static inline int raw_cmd_copyin(int cmd, char __user *param,
 		if (!ptr)
 			return -ENOMEM;
 		*rcmd = ptr;
-		COPYIN(*ptr);
+		ret = _COPYIN(*ptr);
 		ptr->next = NULL;
 		ptr->buffer_length = 0;
+		ptr->kernel_data = NULL;
+		if (ret)
+			return ret;
 		param += sizeof(struct floppy_raw_cmd);
 		if (ptr->cmd_count > 33)
 			/* the command may now also take up the space
@@ -3227,7 +3230,6 @@ static inline int raw_cmd_copyin(int cmd, char __user *param,
 		for (i = 0; i < 16; i++)
 			ptr->reply[i] = 0;
 		ptr->resultcode = 0;
-		ptr->kernel_data = NULL;
 
 		if (ptr->flags & (FD_RAW_READ | FD_RAW_WRITE)) {
 			if (ptr->length <= 0)
-- 
1.9.1