[Xen-devel] [PATCH v2 2/2] hvmloader: use bound checking in get_module_entry

[Wei Liu <wei.liu2@xxxxxxxxxx>]

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>
---
 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++ )
-- 
2.1.4


_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxx
https://lists.xen.org/xen-devel