[Xen-changelog] [xen stable-4.2] libxc: check blob size before proceeding in xc_dom_check_gzip

[patchbot@xxxxxxx]

commit 2a548e22915535ac13694eb38222903bca7245e3
Author:     Matthew Daley <mattjd@xxxxxxxxx>
AuthorDate: Fri Jun 14 16:43:19 2013 +0100
Commit:     Ian Jackson <Ian.Jackson@xxxxxxxxxxxxx>
CommitDate: Fri Jun 14 16:43:19 2013 +0100

    libxc: check blob size before proceeding in xc_dom_check_gzip
    
    This is part of the fix to a security issue, XSA-55.
    
    Signed-off-by: Matthew Daley <mattjd@xxxxxxxxx>
---
 tools/libxc/xc_dom_core.c |    5 +++++
 1 files changed, 5 insertions(+), 0 deletions(-)

diff --git a/tools/libxc/xc_dom_core.c b/tools/libxc/xc_dom_core.c
index 3cbf9f7..f8d1b08 100644
--- a/tools/libxc/xc_dom_core.c
+++ b/tools/libxc/xc_dom_core.c
@@ -284,6 +284,11 @@ size_t xc_dom_check_gzip(xc_interface *xch, void *blob, 
size_t ziplen)
     unsigned char *gzlen;
     size_t unziplen;
 
+    if ( ziplen < 6 )
+        /* Too small.  We need (i.e. the subsequent code relies on)
+         * 2 bytes for the magic number plus 4 bytes length. */
+        return 0;
+
     if ( strncmp(blob, "\037\213", 2) )
         /* not gzipped */
         return 0;
--
generated by git-patchbot for /home/xen/git/xen.git#stable-4.2

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