[PATCH 7/9] virconf: Properly fix numeric overflow when parsing numbers in conf files

[Peter Krempa <pkrempa@xxxxxxxxxx>]

The previous fix didn't check the overflow in addition. Use the new
macro to check both multiplication and addition overflows.

Fixes: 8666523b7d0891c38a7c9c138c4cc318eddfefeb
Closes: https://gitlab.com/libvirt/libvirt/-/issues/671
Signed-off-by: Peter Krempa <pkrempa@xxxxxxxxxx>
---
 src/util/virconf.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/src/util/virconf.c b/src/util/virconf.c
index da07af178d..66b3e0482e 100644
--- a/src/util/virconf.c
+++ b/src/util/virconf.c
@@ -347,13 +347,15 @@ virConfParseLong(virConfParserCtxt *ctxt, long long *val)
         return -1;
     }
     while ((ctxt->cur < ctxt->end) && (g_ascii_isdigit(CUR))) {
-        if (l > LLONG_MAX / 10) {
+        long long c = (CUR - '0');
+
+        if (VIR_MULTIPLY_ADD_IS_OVERFLOW(LLONG_MAX, l, 10, c)) {
             virConfError(ctxt, VIR_ERR_OVERFLOW,
                          _("numeric overflow in conf value"));
             return -1;
         }

-        l = l * 10 + (CUR - '0');
+        l = l * 10 + c;
         NEXT;
     }
     if (neg)
-- 
2.46.0