From 34716e2a6ee2af96078d62b065b7785c001194be Mon Sep 17 00:00:00 2001

From: David Mitchell <davem@iabyn.com>

Date: Fri, 29 Jun 2018 13:37:03 +0100

Subject: [PATCH] Perl_my_setenv(); handle integer wrap

RT #133204

Wean this function off int/I32 and onto UV/Size_t.

Also, replace all malloc-ish calls with a wrapper that does

overflow checks,

In particular, it was doing (nlen + vlen + 2) which could wrap when

the combined length of the environment variable name and value

exceeded around 0x7fffffff.

The wrapper check function is probably overkill, but belt and braces...

NB this function has several variant parts, #ifdef'ed by platform

type; I have blindly changed the parts that aren't compiled under linux.

---

 util.c | 76 ++++++++++++++++++++++++++++++++++++++++------------------

 1 file changed, 53 insertions(+), 23 deletions(-)

diff --git a/util.c b/util.c

index 7282dd9cfe..c5c7becc0f 100644

--- a/util.c

+++ b/util.c

@@ -2162,8 +2162,40 @@ Perl_new_warnings_bitfield(pTHX_ STRLEN *buffer, const char *const bits,

    *(s+(nlen+1+vlen)) = '\0'

 #ifdef USE_ENVIRON_ARRAY

-       /* VMS' my_setenv() is in vms.c */

+

+/* small wrapper for use by Perl_my_setenv that mallocs, or reallocs if

+ * 'current' is non-null, with up to three sizes that are added together.

+ * It handles integer overflow.

+ */

+static char *

+S_env_alloc(void *current, Size_t l1, Size_t l2, Size_t l3, Size_t size)

+{

+    void *p;

+    Size_t sl, l = l1 + l2;

+

+    if (l < l2)

+        goto panic;

+    l += l3;

+    if (l < l3)

+        goto panic;

+    sl = l * size;

+    if (sl < l)

+        goto panic;

+

+    p = current

+            ? safesysrealloc(current, sl)

+            : safesysmalloc(sl);

+    if (p)

+        return (char*)p;

+

+  panic:

+    croak_memory_wrap();

+}

+

+

+/* VMS' my_setenv() is in vms.c */

 #if !defined(WIN32) && !defined(NETWARE)

+

 void

 Perl_my_setenv(pTHX_ const char *nam, const char *val)

 {

@@ -2179,28 +2211,27 @@ Perl_my_setenv(pTHX_ const char *nam, const char *val)

 #ifndef PERL_USE_SAFE_PUTENV

     if (!PL_use_safe_putenv) {

         /* most putenv()s leak, so we manipulate environ directly */

-        I32 i;

-        const I32 len = strlen(nam);

-        int nlen, vlen;

+        UV i;

+        Size_t vlen, nlen = strlen(nam);

         /* where does it go? */

         for (i = 0; environ[i]; i++) {

-            if (strnEQ(environ[i],nam,len) && environ[i][len] == '=')

+            if (strnEQ(environ[i], nam, nlen) && environ[i][nlen] == '=')

                 break;

         }

         if (environ == PL_origenviron) {   /* need we copy environment? */

-            I32 j;

-            I32 max;

+            UV j, max;

             char **tmpenv;

             max = i;

             while (environ[max])

                 max++;

-            tmpenv = (char**)safesysmalloc((max+2) * sizeof(char*));

+            /* XXX shouldn't that be max+1 rather than max+2 ??? - DAPM */

+            tmpenv = (char**)S_env_alloc(NULL, max, 2, 0, sizeof(char*));

             for (j=0; j

-                const int len = strlen(environ[j]);

-                tmpenv[j] = (char*)safesysmalloc((len+1)*sizeof(char));

+                const Size_t len = strlen(environ[j]);

+                tmpenv[j] = S_env_alloc(NULL, len, 1, 0, 1);

                 Copy(environ[j], tmpenv[j], len+1, char);

             }

             tmpenv[max] = NULL;

@@ -2219,15 +2250,15 @@ Perl_my_setenv(pTHX_ const char *nam, const char *val)

 #endif

         }

         if (!environ[i]) {                 /* does not exist yet */

-            environ = (char**)safesysrealloc(environ, (i+2) * sizeof(char*));

+            environ = (char**)S_env_alloc(environ, i, 2, 0, sizeof(char*));

             environ[i+1] = NULL;    /* make sure it's null terminated */

         }

         else

             safesysfree(environ[i]);

-        nlen = strlen(nam);

+

         vlen = strlen(val);

-        environ[i] = (char*)safesysmalloc((nlen+vlen+2) * sizeof(char));

+        environ[i] = S_env_alloc(NULL, nlen, vlen, 2, 1);

         /* all that work just for this */

         my_setenv_format(environ[i], nam, nlen, val, vlen);

     } else {

@@ -2252,22 +2283,21 @@ Perl_my_setenv(pTHX_ const char *nam, const char *val)

             if (environ) /* old glibc can crash with null environ */

                 (void)unsetenv(nam);

         } else {

-	    const int nlen = strlen(nam);

-	    const int vlen = strlen(val);

-	    char * const new_env =

-                (char*)safesysmalloc((nlen + vlen + 2) * sizeof(char));

+	    const Size_t nlen = strlen(nam);

+	    const Size_t vlen = strlen(val);

+	    char * const new_env = S_env_alloc(NULL, nlen, vlen, 2, 1);

             my_setenv_format(new_env, nam, nlen, val, vlen);

             (void)putenv(new_env);

         }

 #       else /* ! HAS_UNSETENV */

         char *new_env;

-	const int nlen = strlen(nam);

-	int vlen;

+	const Size_t nlen = strlen(nam);

+	Size_t vlen;

         if (!val) {

 	   val = "";

         }

         vlen = strlen(val);

-        new_env = (char*)safesysmalloc((nlen + vlen + 2) * sizeof(char));

+        new_env = S_env_alloc(NULL, nlen, vlen, 2, 1);

         /* all that work just for this */

         my_setenv_format(new_env, nam, nlen, val, vlen);

         (void)putenv(new_env);

@@ -2290,14 +2320,14 @@ Perl_my_setenv(pTHX_ const char *nam, const char *val)

 {

     dVAR;

     char *envstr;

-    const int nlen = strlen(nam);

-    int vlen;

+    const Size_t nlen = strlen(nam);

+    Size_t vlen;

     if (!val) {

        val = "";

     }

     vlen = strlen(val);

-    Newx(envstr, nlen+vlen+2, char);

+    envstr = S_env_alloc(NULL, nlen, vlen, 2, 1);

     my_setenv_format(envstr, nam, nlen, val, vlen);

     (void)PerlEnv_putenv(envstr);

     Safefree(envstr);

-- 

2.17.1