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

From: Jens Axboe
Date: Mon Jul 27 2020 - 12:25:47 EST

On 7/27/20 10:19 AM, Peilin Ye wrote:
> 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 initializing `cgc32` using memset().

Could also just add the appropriate pad, so the compiler does the
right thing.

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];

Jens Axboe