tools/xg: Fix potential memory leak in cpu policy getters/setters

They allocate two different hypercall buffers, but leak the first
allocation if the second one failed due to an early return that bypasses
cleanup.

Remove the early exit and go through _post() instead. Invoking _post() is
benign even if _pre() failed.

Fixes: 6b85e427098c ('x86/sysctl: Implement XEN_SYSCTL_get_cpu_policy')
Fixes: 60529dfeca14 ('x86/domctl: Implement XEN_DOMCTL_get_cpu_policy')
Fixes: 14ba07e6f816 ('x86/domctl: Implement XEN_DOMCTL_set_cpumsr_policy')
Signed-off-by: Alejandro Vallejo <alejandro.vallejo@cloud.com>
Reviewed-by: Anthony PERARD <anthony.perard@citrix.com>
master commit: 1571ff7a987b88b20598a6d49910457f3b2c59f1
master date: 2023-12-01 10:53:07 +0100

diff --git a/tools/libs/guest/xg_cpuid_x86.c b/tools/libs/guest/xg_cpuid_x86.c
index 0c7d162da6b17062cfba67ca50c8d9af8c01b033..84babe6908762e2921adff04fdf8c6c5a0560497 100644 (file)
--- a/tools/libs/guest/xg_cpuid_x86.c
+++ b/tools/libs/guest/xg_cpuid_x86.c
@@ -136,20 +136,20 @@ static int get_system_cpu_policy(xc_interface *xch, uint32_t index,
     DECLARE_HYPERCALL_BOUNCE(msrs,
                              *nr_msrs * sizeof(*msrs),
                              XC_HYPERCALL_BUFFER_BOUNCE_OUT);
-    int ret;
-
-    if ( xc_hypercall_bounce_pre(xch, leaves) ||
-         xc_hypercall_bounce_pre(xch, msrs) )
-        return -1;
+    int ret = -1;
 
-    sysctl.cmd = XEN_SYSCTL_get_cpu_policy;
-    sysctl.u.cpu_policy.index = index;
-    sysctl.u.cpu_policy.nr_leaves = *nr_leaves;
-    set_xen_guest_handle(sysctl.u.cpu_policy.leaves, leaves);
-    sysctl.u.cpu_policy.nr_msrs = *nr_msrs;
-    set_xen_guest_handle(sysctl.u.cpu_policy.msrs, msrs);
-
-    ret = do_sysctl(xch, &sysctl);
+    if ( !xc_hypercall_bounce_pre(xch, leaves) &&
+         !xc_hypercall_bounce_pre(xch, msrs) )
+    {
+        sysctl.cmd = XEN_SYSCTL_get_cpu_policy;
+        sysctl.u.cpu_policy.index = index;
+        sysctl.u.cpu_policy.nr_leaves = *nr_leaves;
+        set_xen_guest_handle(sysctl.u.cpu_policy.leaves, leaves);
+        sysctl.u.cpu_policy.nr_msrs = *nr_msrs;
+        set_xen_guest_handle(sysctl.u.cpu_policy.msrs, msrs);
+
+        ret = do_sysctl(xch, &sysctl);
+    }
 
     xc_hypercall_bounce_post(xch, leaves);
     xc_hypercall_bounce_post(xch, msrs);
@@ -174,20 +174,20 @@ static int get_domain_cpu_policy(xc_interface *xch, uint32_t domid,
     DECLARE_HYPERCALL_BOUNCE(msrs,
                              *nr_msrs * sizeof(*msrs),
                              XC_HYPERCALL_BUFFER_BOUNCE_OUT);
-    int ret;
-
-    if ( xc_hypercall_bounce_pre(xch, leaves) ||
-         xc_hypercall_bounce_pre(xch, msrs) )
-        return -1;
-
-    domctl.cmd = XEN_DOMCTL_get_cpu_policy;
-    domctl.domain = domid;
-    domctl.u.cpu_policy.nr_leaves = *nr_leaves;
-    set_xen_guest_handle(domctl.u.cpu_policy.leaves, leaves);
-    domctl.u.cpu_policy.nr_msrs = *nr_msrs;
-    set_xen_guest_handle(domctl.u.cpu_policy.msrs, msrs);
+    int ret = -1;
 
-    ret = do_domctl(xch, &domctl);
+    if ( !xc_hypercall_bounce_pre(xch, leaves) &&
+         !xc_hypercall_bounce_pre(xch, msrs) )
+    {
+        domctl.cmd = XEN_DOMCTL_get_cpu_policy;
+        domctl.domain = domid;
+        domctl.u.cpu_policy.nr_leaves = *nr_leaves;
+        set_xen_guest_handle(domctl.u.cpu_policy.leaves, leaves);
+        domctl.u.cpu_policy.nr_msrs = *nr_msrs;
+        set_xen_guest_handle(domctl.u.cpu_policy.msrs, msrs);
+
+        ret = do_domctl(xch, &domctl);
+    }
 
     xc_hypercall_bounce_post(xch, leaves);
     xc_hypercall_bounce_post(xch, msrs);
@@ -214,32 +214,24 @@ int xc_set_domain_cpu_policy(xc_interface *xch, uint32_t domid,
     DECLARE_HYPERCALL_BOUNCE(msrs,
                              nr_msrs * sizeof(*msrs),
                              XC_HYPERCALL_BUFFER_BOUNCE_IN);
-    int ret;
-
-    if ( err_leaf_p )
-        *err_leaf_p = -1;
-    if ( err_subleaf_p )
-        *err_subleaf_p = -1;
-    if ( err_msr_p )
-        *err_msr_p = -1;
+    int ret = -1;
 
-    if ( xc_hypercall_bounce_pre(xch, leaves) )
-        return -1;
-
-    if ( xc_hypercall_bounce_pre(xch, msrs) )
-        return -1;
-
-    domctl.cmd = XEN_DOMCTL_set_cpu_policy;
-    domctl.domain = domid;
-    domctl.u.cpu_policy.nr_leaves = nr_leaves;
-    set_xen_guest_handle(domctl.u.cpu_policy.leaves, leaves);
-    domctl.u.cpu_policy.nr_msrs = nr_msrs;
-    set_xen_guest_handle(domctl.u.cpu_policy.msrs, msrs);
     domctl.u.cpu_policy.err_leaf = -1;
     domctl.u.cpu_policy.err_subleaf = -1;
     domctl.u.cpu_policy.err_msr = -1;
 
-    ret = do_domctl(xch, &domctl);
+    if ( !xc_hypercall_bounce_pre(xch, leaves) &&
+         !xc_hypercall_bounce_pre(xch, msrs) )
+    {
+        domctl.cmd = XEN_DOMCTL_set_cpu_policy;
+        domctl.domain = domid;
+        domctl.u.cpu_policy.nr_leaves = nr_leaves;
+        set_xen_guest_handle(domctl.u.cpu_policy.leaves, leaves);
+        domctl.u.cpu_policy.nr_msrs = nr_msrs;
+        set_xen_guest_handle(domctl.u.cpu_policy.msrs, msrs);
+
+        ret = do_domctl(xch, &domctl);
+    }
 
     xc_hypercall_bounce_post(xch, leaves);
     xc_hypercall_bounce_post(xch, msrs);