[Xen-devel] [PATCH for-4.5 1/3] python/xc: Fix multiple issues in pyflask_context_to_sid()

[Andrew Cooper <andrew.cooper3@xxxxxxxxxx>]

The error handling from a failed memory allocation should return
PyErr_SetFromErrno(xc_error_obj); rather than simply calling it and continuing
to the memcpy() below, with the dest pointer being NULL.

Furthermore, the context string is simply an input parameter to the hypercall,
and is not mutated anywhere along the way.  The error handling elsewhere in
the function can be simplified by not duplicating it to start with.

Signed-off-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
Coverity-IDs: 1055305 1055721
CC: Ian Campbell <Ian.Campbell@xxxxxxxxxx>
CC: Ian Jackson <Ian.Jackson@xxxxxxxxxxxxx>
CC: Wei Liu <wei.liu2@xxxxxxxxxx>
CC: Xen Coverity Team <coverity@xxxxxxx>
---
 tools/python/xen/lowlevel/xc/xc.c |   21 +++------------------
 1 file changed, 3 insertions(+), 18 deletions(-)

diff --git a/tools/python/xen/lowlevel/xc/xc.c 
b/tools/python/xen/lowlevel/xc/xc.c
index d95d459..c70b388 100644
--- a/tools/python/xen/lowlevel/xc/xc.c
+++ b/tools/python/xen/lowlevel/xc/xc.c
@@ -2126,8 +2126,6 @@ static PyObject *pyflask_context_to_sid(PyObject *self, 
PyObject *args,
 {
     xc_interface *xc_handle;
     char *ctx;
-    char *buf;
-    uint32_t len;
     uint32_t sid;
     int ret;
 
@@ -2137,28 +2135,15 @@ static PyObject *pyflask_context_to_sid(PyObject *self, 
PyObject *args,
                                       &ctx) )
         return NULL;
 
-    len = strlen(ctx);
-
-    buf = malloc(len);
-    if (!buf) {
-        errno = -ENOMEM;
-        PyErr_SetFromErrno(xc_error_obj);
-    }
-    
-    memcpy(buf, ctx, len);
-    
     xc_handle = xc_interface_open(0,0,0);
     if (!xc_handle) {
-        free(buf);
         return PyErr_SetFromErrno(xc_error_obj);
     }
-    
-    ret = xc_flask_context_to_sid(xc_handle, buf, len, &sid);
-        
+
+    ret = xc_flask_context_to_sid(xc_handle, ctx, strlen(ctx), &sid);
+
     xc_interface_close(xc_handle);
 
-    free(buf);
-    
     if ( ret != 0 ) {
         errno = -ret;
         return PyErr_SetFromErrno(xc_error_obj);
-- 
1.7.10.4


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