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From a75fb7b198eed50d769c80c36629f38346882cbf Mon Sep 17 00:00:00 2001
From: Paul Mackerras <paulus@ozlabs.org>
Date: Thu, 4 Aug 2022 12:23:08 +1000
Subject: [PATCH] pppdump: Avoid out-of-range access to packet buffer
This fixes a potential vulnerability where data is written to spkt.buf
and rpkt.buf without a check on the array index. To fix this, we
check the array index (pkt->cnt) before storing the byte or
incrementing the count. This also means we no longer have a potential
signed integer overflow on the increment of pkt->cnt.
Fortunately, pppdump is not used in the normal process of setting up a
PPP connection, is not installed setuid-root, and is not invoked
automatically in any scenario that I am aware of.
Signed-off-by: Paul Mackerras <paulus@ozlabs.org>
Upstream-Status: Backport
Signed-off-by: Ross Burton <ross.burton@arm.com>
---
pppdump/pppdump.c | 7 ++++++-
1 file changed, 6 insertions(+), 1 deletion(-)
diff --git a/pppdump/pppdump.c b/pppdump/pppdump.c
index 2b815fc9..b85a8627 100644
--- a/pppdump/pppdump.c
+++ b/pppdump/pppdump.c
@@ -297,6 +297,10 @@ dumpppp(f)
printf("%s aborted packet:\n ", dir);
q = " ";
}
+ if (pkt->cnt >= sizeof(pkt->buf)) {
+ printf("%s over-long packet truncated:\n ", dir);
+ q = " ";
+ }
nb = pkt->cnt;
p = pkt->buf;
pkt->cnt = 0;
@@ -400,7 +404,8 @@ dumpppp(f)
c ^= 0x20;
pkt->esc = 0;
}
- pkt->buf[pkt->cnt++] = c;
+ if (pkt->cnt < sizeof(pkt->buf))
+ pkt->buf[pkt->cnt++] = c;
break;
}
}
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