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From e8a1e037afc8729bd65d4bda36dedf444f301c0f Mon Sep 17 00:00:00 2001
From: Rolf Eike Beer <eike@sf-mail.de>
Date: Mon, 11 May 2020 18:30:13 +0200
Subject: [PATCH 4/4] fix additional length overflows

---
 Makefile        |  6 +++---
 alloc.c         | 21 ++++++++++++++-------
 qmail-local.c   |  3 ++-
 qmail-pop3d.c   |  3 ++-
 quote.c         | 10 +++++++++-
 stralloc_catb.c |  8 +++++++-
 stralloc_opyb.c |  8 +++++++-
 substdo.c       |  4 ++--
 8 files changed, 46 insertions(+), 17 deletions(-)

diff --git a/Makefile b/Makefile
index 0f0e31a..4b592c6 100644
--- a/Makefile
+++ b/Makefile
@@ -1673,7 +1673,7 @@ qsutil.h
 	./compile qsutil.c
 
 quote.o: \
-compile quote.c stralloc.h gen_alloc.h str.h quote.h
+compile quote.c stralloc.h gen_alloc.h str.h quote.h error.h
 	./compile quote.c
 
 rcpthosts.o: \
@@ -1965,7 +1965,7 @@ compile stralloc_cat.c byte.h stralloc.h gen_alloc.h
 	./compile stralloc_cat.c
 
 stralloc_catb.o: \
-compile stralloc_catb.c stralloc.h gen_alloc.h byte.h
+compile stralloc_catb.c stralloc.h gen_alloc.h byte.h error.h
 	./compile stralloc_catb.c
 
 stralloc_cats.o: \
@@ -1982,7 +1982,7 @@ gen_allocdefs.h
 	./compile stralloc_eady.c
 
 stralloc_opyb.o: \
-compile stralloc_opyb.c stralloc.h gen_alloc.h byte.h
+compile stralloc_opyb.c stralloc.h gen_alloc.h byte.h error.h
 	./compile stralloc_opyb.c
 
 stralloc_opys.o: \
diff --git a/alloc.c b/alloc.c
index c661453..3ab5f6f 100644
--- a/alloc.c
+++ b/alloc.c
@@ -1,7 +1,6 @@
+#include <stdlib.h>
 #include "alloc.h"
 #include "error.h"
-extern char *malloc();
-extern void free();
 
 #define ALIGNMENT 16 /* XXX: assuming that this alignment is enough */
 #define SPACE 4096 /* must be multiple of ALIGNMENT */
@@ -11,15 +10,23 @@ static aligned realspace[SPACE / ALIGNMENT];
 #define space ((char *) realspace)
 static unsigned int avail = SPACE; /* multiple of ALIGNMENT; 0<=avail<=SPACE */
 
+static char *m_alloc(unsigned int n)
+{
+  char *x = malloc(n);
+  if (!x) errno = error_nomem;
+  return x;
+}
+
 /*@null@*//*@out@*/char *alloc(n)
 unsigned int n;
 {
-  char *x;
-  n = ALIGNMENT + n - (n & (ALIGNMENT - 1)); /* XXX: could overflow */
+  if (n >= SPACE)
+    return m_alloc(n);
+  /* Round it up to the next multiple of alignment. Could overflow if n is
+   * close to 2**32, but by the check above this is already ruled out. */
+  n = ALIGNMENT + n - (n & (ALIGNMENT - 1));
   if (n <= avail) { avail -= n; return space + avail; }
-  x = malloc(n);
-  if (!x) errno = error_nomem;
-  return x;
+  return m_alloc(n);
 }
 
 void alloc_free(x)
diff --git a/qmail-local.c b/qmail-local.c
index 6fec288..f5e33fd 100644
--- a/qmail-local.c
+++ b/qmail-local.c
@@ -1,5 +1,6 @@
 #include <sys/types.h>
 #include <sys/stat.h>
+#include <stdlib.h>
 #include "readwrite.h"
 #include "sig.h"
 #include "env.h"
@@ -633,7 +634,7 @@ char **argv;
      i = j + 1;
     }
 
- recips = (char **) alloc((numforward + 1) * sizeof(char *));
+ recips = (char **) calloc(numforward + 1, sizeof(char *));
  if (!recips) temp_nomem();
  numforward = 0;
 
diff --git a/qmail-pop3d.c b/qmail-pop3d.c
index 0ca4f9c..1916433 100644
--- a/qmail-pop3d.c
+++ b/qmail-pop3d.c
@@ -1,5 +1,6 @@
 #include <sys/types.h>
 #include <sys/stat.h>
+#include <stdlib.h>
 #include "commands.h"
 #include "sig.h"
 #include "getln.h"
@@ -131,7 +132,7 @@ void getlist()
   if (maildir_scan(&pq,&filenames,1,1) == -1) die_scan();
  
   numm = pq.p ? pq.len : 0;
-  m = (struct message *) alloc(numm * sizeof(struct message));
+  m = (struct message *) calloc(numm, sizeof(struct message));
   if (!m) die_nomem();
  
   for (i = 0;i < numm;++i) {
diff --git a/quote.c b/quote.c
index 659cfcd..73b7214 100644
--- a/quote.c
+++ b/quote.c
@@ -1,3 +1,4 @@
+#include "error.h"
 #include "stralloc.h"
 #include "str.h"
 #include "quote.h"
@@ -23,8 +24,15 @@ stralloc *sain;
  char ch;
  int i;
  int j;
+ unsigned int nlen;
 
- if (!stralloc_ready(saout,sain->len * 2 + 2)) return 0;
+ /* make sure the size calculation below does not overflow */
+ if (__builtin_mul_overflow(sain->len, 2, &nlen) ||
+     __builtin_add_overflow(nlen, 2, &nlen)) {
+   errno = error_nomem;
+   return 0;
+ }
+ if (!stralloc_ready(saout,nlen)) return 0;
  j = 0;
  saout->s[j++] = '"';
  for (i = 0;i < sain->len;++i)
diff --git a/stralloc_catb.c b/stralloc_catb.c
index 67dbcc0..a315810 100644
--- a/stralloc_catb.c
+++ b/stralloc_catb.c
@@ -1,13 +1,19 @@
 #include "stralloc.h"
 #include "byte.h"
+#include "error.h"
 
 int stralloc_catb(sa,s,n)
 stralloc *sa;
 char *s;
 unsigned int n;
 {
+  unsigned int i;
   if (!sa->s) return stralloc_copyb(sa,s,n);
-  if (!stralloc_readyplus(sa,n + 1)) return 0;
+  if (__builtin_add_overflow(n, 1, &i)) {
+    errno = error_nomem;
+    return 0;
+  }
+  if (!stralloc_readyplus(sa,i)) return 0;
   byte_copy(sa->s + sa->len,n,s);
   sa->len += n;
   sa->s[sa->len] = 'Z'; /* ``offensive programming'' */
diff --git a/stralloc_opyb.c b/stralloc_opyb.c
index ac258b3..8a6f305 100644
--- a/stralloc_opyb.c
+++ b/stralloc_opyb.c
@@ -1,12 +1,18 @@
 #include "stralloc.h"
 #include "byte.h"
+#include "error.h"
 
 int stralloc_copyb(sa,s,n)
 stralloc *sa;
 char *s;
 unsigned int n;
 {
-  if (!stralloc_ready(sa,n + 1)) return 0;
+  unsigned int i;
+  if (__builtin_add_overflow(n, 1, &i)) {
+    errno = error_nomem;
+    return 0;
+  }
+  if (!stralloc_ready(sa,i)) return 0;
   byte_copy(sa->s,n,s);
   sa->len = n;
   sa->s[n] = 'Z'; /* ``offensive programming'' */
diff --git a/substdo.c b/substdo.c
index bccf0d6..ad7232a 100644
--- a/substdo.c
+++ b/substdo.c
@@ -38,9 +38,9 @@ register substdio *s;
 int substdio_bput(s,buf,len)
 register substdio *s;
 register char *buf;
-register int len;
+register unsigned int len;
 {
-  register int n;
+  register unsigned int n;
  
   while (len > (n = s->n - s->p)) {
     byte_copy(s->x + s->p,n,buf); s->p += n; buf += n; len -= n;
-- 
2.26.1