[Linux-kernel-mentees] [PATCH v2] block/scsi-ioctl: Prevent kernel-infoleak in scsi_put_cdrom_generic_arg()

[Peilin Ye]

scsi_put_cdrom_generic_arg() is copying uninitialized stack memory to
userspace due to the compiler not initializing holes in statically
allocated structures. Fix it by adding a padding field to `struct
compat_cdrom_generic_command`.

Cc: stable at vger.kernel.org
Fixes: f3ee6e63a9df ("compat_ioctl: move CDROM_SEND_PACKET handling into scsi")
Suggested-by: Dan Carpenter <dan.carpenter at oracle.com>
Suggested-by: Arnd Bergmann <arnd at arndb.de>
Signed-off-by: Peilin Ye <yepeilin.cs at gmail.com>
---
Change in v2:
    - Add a padding field to `struct compat_cdrom_generic_command`,
      instead of doing memset() on `cgc32`. (Suggested by Jens Axboe
      <axboe at kernel.dk>)

 block/scsi_ioctl.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/block/scsi_ioctl.c b/block/scsi_ioctl.c
index ef722f04f88a..72108404718f 100644
--- a/block/scsi_ioctl.c
+++ b/block/scsi_ioctl.c
@@ -651,6 +651,7 @@ struct compat_cdrom_generic_command {
 	compat_int_t	stat;
 	compat_caddr_t	sense;
 	unsigned char	data_direction;
+	unsigned char	pad[3];
 	compat_int_t	quiet;
 	compat_int_t	timeout;
 	compat_caddr_t	reserved[1];
-- 
2.25.1