[Xen-changelog] [xen master] tools: libxl: free devpath on failure in libxl__blktap_devpath

[patchbot@xxxxxxx]

commit 382c72d83ad032e985bfcaa2dbb6bf78859b380e
Author:     Ian Campbell <ian.campbell@xxxxxxxxxx>
AuthorDate: Tue Feb 16 11:09:43 2016 +0000
Commit:     Ian Jackson <Ian.Jackson@xxxxxxxxxxxxx>
CommitDate: Tue Feb 16 17:37:11 2016 +0000

    tools: libxl: free devpath on failure in libxl__blktap_devpath
    
    The underlying code paths in tap_ctl_create attempt to handle both
    *devpath == NULL (by allocating) and *devpath != NULL (caller provided
    name) and if they allocate tend to write the return immediately before
    doing other potentially error generating tasks. All of which makes
    handling this at a lower level rather more complicated than handling
    it in the error path of libxl__blktap_devpath.
    
    Note that libxl__blktap_devpath initialises devpath to NULL and if the
    earlier GCSPRINTF succeeds then the value is returned earlier.
    Therefore if we make it to the call to tap_ctl_create then devpath is
    still NULL on entry, therefore on the error path devpath is either
    still NULL or has been set to a freshly allocated value by
    tap_ctl_create. Since free(NULL) is fine it is sufficient to just
    free(devpath).
    
    I also considered adding a non-NULL devnull to the gc, even on
    failure, but that would have required a comment to explain the
    apparently strange behaviour.
    
    Compile tested only.
    
    CID: 1215177
    
    Signed-off-by: Ian Campbell <ian.campbell@xxxxxxxxxx>
    Acked-by: Wei Liu <wei.liu2@xxxxxxxxxx>
---
 tools/libxl/libxl_blktap2.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/tools/libxl/libxl_blktap2.c b/tools/libxl/libxl_blktap2.c
index 4f5e522..5c9a0a2 100644
--- a/tools/libxl/libxl_blktap2.c
+++ b/tools/libxl/libxl_blktap2.c
@@ -47,6 +47,7 @@ char *libxl__blktap_devpath(libxl__gc *gc,
         return devname;
     }
 
+    free(devname);
     return NULL;
 }
 
--
generated by git-patchbot for /home/xen/git/xen.git#master

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