From 58725d71e4306c83a474d6c3035e72580d0c4592 Mon Sep 17 00:00:00 2001
From: hopper-vul <118949689+hopper-vul@users.noreply.github.com>
Date: Wed, 18 Jan 2023 22:14:26 +0800
Subject: [PATCH] deps(cares): Add str len check in config_sortlist to avoid
 stack overflow (#497)

In ares_set_sortlist, it calls config_sortlist(..., sortstr) to parse
the input str and initialize a sortlist configuration.

However, ares_set_sortlist has not any checks about the validity of the input str.
It is very easy to create an arbitrary length stack overflow with the unchecked
`memcpy(ipbuf, str, q-str);` and `memcpy(ipbufpfx, str, q-str);`
statements in the config_sortlist call, which could potentially cause severe
security impact in practical programs.

This commit add necessary check for `ipbuf` and `ipbufpfx` which avoid the
potential stack overflows.

fixes #496

Fix By: @hopper-vul

Signed-off-by: rpm-build <rpm-build>
---
 deps/cares/src/lib/ares_init.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/deps/cares/src/lib/ares_init.c b/deps/cares/src/lib/ares_init.c
index de5d86c..d5858f6 100644
--- a/deps/cares/src/lib/ares_init.c
+++ b/deps/cares/src/lib/ares_init.c
@@ -2243,6 +2243,8 @@ static int config_sortlist(struct apattern **sortlist, int *nsort,
       q = str;
       while (*q && *q != '/' && *q != ';' && !ISSPACE(*q))
         q++;
+      if (q-str >= 16)
+        return ARES_EBADSTR;
       memcpy(ipbuf, str, q-str);
       ipbuf[q-str] = '\0';
       /* Find the prefix */
@@ -2251,6 +2253,8 @@ static int config_sortlist(struct apattern **sortlist, int *nsort,
           const char *str2 = q+1;
           while (*q && *q != ';' && !ISSPACE(*q))
             q++;
+          if (q-str >= 32)
+            return ARES_EBADSTR;
           memcpy(ipbufpfx, str, q-str);
           ipbufpfx[q-str] = '\0';
           str = str2;
-- 
2.39.2