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tcm_vhost: Fix vhost_scsi_target structure alignment

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Here TRANSPORT_IQN_LEN is 224, which is a multiple of 4.
Since vhost_tpgt is 2 bytes and abi_version is 4, the total size would
be 230.  But gcc needs struct size be aligned to first field size, which
is 4 bytes, so it pads the structure by extra 2 bytes to the total of
232.

This padding is very undesirable in an ABI:
- it can not be initialized easily
- it can not be checked easily
- it can leak information between kernel and userspace

Simplest solution is probably just to make the padding
explicit.

(v2: Add check for zero'ed backend->reserved field for VHOST_SCSI_SET_ENDPOINT
     and VHOST_SCSI_CLEAR_ENDPOINT ops as requested by MST)

Reported-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>
This commit is contained in:
Michael S. Tsirkin 2012-08-18 15:44:09 -07:00 committed by Nicholas Bellinger
parent 74f4cf2909
commit 6de7145ca3
2 changed files with 5 additions and 0 deletions
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4
drivers/vhost/tcm_vhost.c
View File

@ -995,11 +995,15 @@ static long vhost_scsi_ioctl(struct file *f, unsigned int ioctl,
case VHOST_SCSI_SET_ENDPOINT:
if (copy_from_user(&backend, argp, sizeof backend))
return -EFAULT;
if (backend.reserved != 0)
return -EOPNOTSUPP;
return vhost_scsi_set_endpoint(vs, &backend);
case VHOST_SCSI_CLEAR_ENDPOINT:
if (copy_from_user(&backend, argp, sizeof backend))
return -EFAULT;
if (backend.reserved != 0)
return -EOPNOTSUPP;
return vhost_scsi_clear_endpoint(vs, &backend);
case VHOST_SCSI_GET_ABI_VERSION:

1
drivers/vhost/tcm_vhost.h
View File

@ -93,6 +93,7 @@ struct vhost_scsi_target {
int abi_version;
char vhost_wwpn[TRANSPORT_IQN_LEN];
unsigned short vhost_tpgt;
unsigned short reserved;
};
/* VHOST_SCSI specific defines */