From 6de7145ca3db231a84b7516a6cb25878da6ebb19 Mon Sep 17 00:00:00 2001 From: "Michael S. Tsirkin" Date: Sat, 18 Aug 2012 15:44:09 -0700 Subject: [PATCH] tcm_vhost: Fix vhost_scsi_target structure alignment 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 Signed-off-by: Michael S. Tsirkin Signed-off-by: Nicholas Bellinger --- drivers/vhost/tcm_vhost.c | 4 ++++ drivers/vhost/tcm_vhost.h | 1 + 2 files changed, 5 insertions(+) diff --git a/drivers/vhost/tcm_vhost.c b/drivers/vhost/tcm_vhost.c index 74b2edaaf1f6..ed8e2e6c8df2 100644 --- a/drivers/vhost/tcm_vhost.c +++ b/drivers/vhost/tcm_vhost.c @@ -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: diff --git a/drivers/vhost/tcm_vhost.h b/drivers/vhost/tcm_vhost.h index e9d5c020fb39..d9e93557d669 100644 --- a/drivers/vhost/tcm_vhost.h +++ b/drivers/vhost/tcm_vhost.h @@ -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 */ -- GitLab