From: Paul Mackerras <paulus@ozlabs.org>
Date: Tue, 20 Aug 2024 10:27:31 +0000 (+1000)
Subject: plugins/pppoatm: Restructure code to avoid possibility of integer overflow
X-Git-Tag: v2.5.1~20
X-Git-Url: https://git.ozlabs.org/?a=commitdiff_plain;h=17f324057084e73d1b21b58906dc3e42b958054f;p=ppp.git

plugins/pppoatm: Restructure code to avoid possibility of integer overflow

This avoids the theoretical possibility of integer overflow in
adding a constant before dividing in order to get the effect of
rounding up.  Instead we divide and add 1 if the original value modulo
the divisor is non-zero.

Signed-off-by: Paul Mackerras <paulus@ozlabs.org>
---

diff --git a/pppd/plugins/pppoatm/text2qos.c b/pppd/plugins/pppoatm/text2qos.c
index 060407a..2da1e50 100644
--- a/pppd/plugins/pppoatm/text2qos.c
+++ b/pppd/plugins/pppoatm/text2qos.c
@@ -66,8 +66,9 @@ int __t2q_get_rate(const char **text,int up)
     }
     else if (!strncmp(end,"cps",3)) end += 3;
 	else if (!strncmp(end,"bps",3)) {
-		rate = (rate+(up ? 8*ATM_CELL_PAYLOAD-1 : 0))/8/
-		  ATM_CELL_PAYLOAD;
+		if (up && rate % (8 * ATM_CELL_PAYLOAD) == 0)
+			up = 0;
+		rate = rate / (8 * ATM_CELL_PAYLOAD) + !!up;
 		end += 3;
 	    }
 	    else if (multiplier) return RATE_ERROR;