From 38ad94acf09f6822d6005144935b58228da33a04 Mon Sep 17 00:00:00 2001 From: Julien Grall Date: Fri, 4 Oct 2019 17:32:49 +0100 Subject: [PATCH] xen/xsm: flask: Prevent NULL deference in flask_assign_{, dt}device() flask_assign_{, dt}device() may be used to check whether you can test if a device is assigned. In this case, the domain will be NULL. However, flask_iommu_resource_use_perm() will be called and may end up to deference a NULL pointer. This can be prevented by moving the call after we check the validity for the domain pointer. Coverity-ID: 1486741 Fixes: 71e617a6b8 ('use is_iommu_enabled() where appropriate...') Signed-off-by: Julien Grall Acked-by: Daniel De Graaf Reviewed-by: Paul Durrant Release-acked-by: Juergen Gross --- xen/xsm/flask/hooks.c | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-) diff --git a/xen/xsm/flask/hooks.c b/xen/xsm/flask/hooks.c index 3b30827764..cf7f25cda2 100644 --- a/xen/xsm/flask/hooks.c +++ b/xen/xsm/flask/hooks.c @@ -1296,11 +1296,13 @@ static int flask_assign_device(struct domain *d, uint32_t machine_bdf) u32 dsid, rsid; int rc = -EPERM; struct avc_audit_data ad; - u32 dperm = flask_iommu_resource_use_perm(d); + u32 dperm; if ( !d ) return flask_test_assign_device(machine_bdf); + dperm = flask_iommu_resource_use_perm(d); + rc = current_has_perm(d, SECCLASS_RESOURCE, RESOURCE__ADD); if ( rc ) return rc; @@ -1355,11 +1357,13 @@ static int flask_assign_dtdevice(struct domain *d, const char *dtpath) u32 dsid, rsid; int rc = -EPERM; struct avc_audit_data ad; - u32 dperm = flask_iommu_resource_use_perm(d); + u32 dperm; if ( !d ) return flask_test_assign_dtdevice(dtpath); + dperm = flask_iommu_resource_use_perm(d); + rc = current_has_perm(d, SECCLASS_RESOURCE, RESOURCE__ADD); if ( rc ) return rc; -- 2.30.2