[Xen-changelog] [xen master] hvmloader: use bound checking in get_module_entry

[patchbot@xxxxxxx]

commit 94d3b9990bf73459919fb5b234d088d1ac41c9da
Author:     Wei Liu <wei.liu2@xxxxxxxxxx>
AuthorDate: Mon Aug 22 13:47:53 2016 +0100
Commit:     Wei Liu <wei.liu2@xxxxxxxxxx>
CommitDate: Mon Aug 22 14:20:19 2016 +0100

    hvmloader: use bound checking in get_module_entry
    
    Coverity complains:
    
    overflow_before_widen: Potentially overflowing expression
    info->nr_modules * 32U with type unsigned int (32 bits, unsigned) is
    evaluated using 32-bit arithmetic, and then used in a context that
    expects an expression of type uint64_t (64 bits, unsigned).
    
    The overflow is unlikely to happen in reality because we only expect a
    few modules.
    
    Fix that by converting the check to use bound checking to placate
    Coverity.
    
    Signed-off-by: Wei Liu <wei.liu2@xxxxxxxxxx>
    Acked-by: Jan Beulich <jbeulich@xxxxxxxx>
---
 tools/firmware/hvmloader/hvmloader.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/tools/firmware/hvmloader/hvmloader.c 
b/tools/firmware/hvmloader/hvmloader.c
index 7b32d86..bbd4e34 100644
--- a/tools/firmware/hvmloader/hvmloader.c
+++ b/tools/firmware/hvmloader/hvmloader.c
@@ -272,8 +272,8 @@ const struct hvm_modlist_entry *get_module_entry(
 
     if ( !modlist ||
          info->modlist_paddr > UINTPTR_MAX ||
-         (info->modlist_paddr + info->nr_modules * sizeof(*modlist) - 1)
-            > UINTPTR_MAX )
+         (UINTPTR_MAX - (uintptr_t)info->modlist_paddr) / sizeof(*modlist)
+         < info->nr_modules )
         return NULL;
 
     for ( i = 0; i < info->nr_modules; i++ )
--
generated by git-patchbot for /home/xen/git/xen.git#master

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