package/network/services/ppp/patches/701-pppd-Fix-bounds-check-in-EAP-code.patch

   1 From 8d7970b8f3db727fe798b65f3377fe6787575426 Mon Sep 17 00:00:00 2001
   2 From: Paul Mackerras <paulus@ozlabs.org>
   3 Date: Mon, 3 Feb 2020 15:53:28 +1100
   4 Subject: [PATCH] pppd: Fix bounds check in EAP code
   5
   6 Given that we have just checked vallen < len, it can never be the case
   7 that vallen >= len + sizeof(rhostname).  This fixes the check so we
   8 actually avoid overflowing the rhostname array.
   9
  10 Reported-by: Ilja Van Sprundel <ivansprundel@ioactive.com>
  11 Signed-off-by: Paul Mackerras <paulus@ozlabs.org>
  12 ---
  13  pppd/eap.c | 4 ++--
  14  1 file changed, 2 insertions(+), 2 deletions(-)
  15
  16 diff --git a/pppd/eap.c b/pppd/eap.c
  17 index 94407f56a336..1b93db01aebd 100644
  18 --- a/pppd/eap.c
  19 +++ b/pppd/eap.c
  20 @@ -1420,7 +1420,7 @@ int len;
  21                 }
  22
  23                 /* Not so likely to happen. */
  24 -               if (vallen >= len + sizeof (rhostname)) {
  25 +               if (len - vallen >= sizeof (rhostname)) {
  26                         dbglog("EAP: trimming really long peer name down");
  27                         BCOPY(inp + vallen, rhostname, sizeof (rhostname) - 1);
  28                         rhostname[sizeof (rhostname) - 1] = '\0';
  29 @@ -1846,7 +1846,7 @@ int len;
  30                 }
  31
  32                 /* Not so likely to happen. */
  33 -               if (vallen >= len + sizeof (rhostname)) {
  34 +               if (len - vallen >= sizeof (rhostname)) {
  35                         dbglog("EAP: trimming really long peer name down");
  36                         BCOPY(inp + vallen, rhostname, sizeof (rhostname) - 1);
  37                         rhostname[sizeof (rhostname) - 1] = '\0';