[nasm:nasm-2.14.xx] rdstrnum: Make sure we dont shift out of bound

[nasm-bot f. C. G. <gor...@gm...>]

Commit-ID:  b756372b0668092f1e189ef097889df0f40dee79
Gitweb:     http://repo.or.cz/w/nasm.git?a=commitdiff;h=b756372b0668092f1e189ef097889df0f40dee79
Author:     Cyrill Gorcunov <gor...@gm...>
AuthorDate: Mon, 29 Oct 2018 22:24:25 +0300
Committer:  Cyrill Gorcunov <gor...@gm...>
CommitDate: Mon, 29 Oct 2018 22:25:16 +0300

rdstrnum: Make sure we dont shift out of bound

Otherwise we may hit underfined behavior.

https://bugzilla.nasm.us/show_bug.cgi?id=3392526

Signed-off-by: Cyrill Gorcunov <gor...@gm...>


---
 asm/rdstrnum.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/asm/rdstrnum.c b/asm/rdstrnum.c
index d9d2a69..319f140 100644
--- a/asm/rdstrnum.c
+++ b/asm/rdstrnum.c
@@ -55,12 +55,14 @@ int64_t readstrnum(char *str, int length, bool *warn)
         for (i = 0; i < length; i++) {
             if (charconst & UINT64_C(0xFF00000000000000))
                 *warn = true;
+            charconst &= ~UINT64_C(0xFF00000000000000);
             charconst = (charconst << 8) + (uint8_t)*--str;
         }
     } else {
         for (i = 0; i < length; i++) {
-            if (charconst & 0xFF000000UL)
+            if (charconst & UINT32_C(0xFF000000))
                 *warn = true;
+            charconst &= ~UINT32_C(0xFF000000);
             charconst = (charconst << 8) + (uint8_t)*--str;
         }
     }