commit 2a54e4be571708976efacca78606a8988afabb06
author Ruslan Ermilov <ru@nginx.com> Tue Mar 17 00:26:15 2015 +0300
committer Ruslan Ermilov <ru@nginx.com> Tue Mar 17 00:26:15 2015 +0300
tree 5474e8f7b72d375c838f240ddae3a4f4a733409e
parent 8fcbfc0b08a6a2ce102e85c3984abf198d2dd64e

Core: overflow detection in number parsing functions.

src/core/ngx_string.c

diff --git a/src/core/ngx_string.c b/src/core/ngx_string.c
index f8641b7..d2a8d01 100644
--- a/src/core/ngx_string.c
+++ b/src/core/ngx_string.c
@@ -901,26 +901,28 @@
 ngx_int_t
 ngx_atoi(u_char *line, size_t n)
 {
-    ngx_int_t  value;
+    ngx_int_t  value, cutoff, cutlim;
 
     if (n == 0) {
         return NGX_ERROR;
     }
 
+    cutoff = NGX_MAX_INT_T_VALUE / 10;
+    cutlim = NGX_MAX_INT_T_VALUE % 10;
+
     for (value = 0; n--; line++) {
         if (*line < '0' || *line > '9') {
             return NGX_ERROR;
         }
 
+        if (value >= cutoff && (value > cutoff || *line - '0' > cutlim)) {
+            return NGX_ERROR;
+        }
+
         value = value * 10 + (*line - '0');
     }
 
-    if (value < 0) {
-        return NGX_ERROR;
-
-    } else {
-        return value;
-    }
+    return value;
 }
 
 
@@ -929,13 +931,16 @@
 ngx_int_t
 ngx_atofp(u_char *line, size_t n, size_t point)
 {
-    ngx_int_t   value;
+    ngx_int_t   value, cutoff, cutlim;
     ngx_uint_t  dot;
 
     if (n == 0) {
         return NGX_ERROR;
     }
 
+    cutoff = NGX_MAX_INT_T_VALUE / 10;
+    cutlim = NGX_MAX_INT_T_VALUE % 10;
+
     dot = 0;
 
     for (value = 0; n--; line++) {
@@ -957,98 +962,107 @@
             return NGX_ERROR;
         }
 
+        if (value >= cutoff && (value > cutoff || *line - '0' > cutlim)) {
+            return NGX_ERROR;
+        }
+
         value = value * 10 + (*line - '0');
         point -= dot;
     }
 
     while (point--) {
+        if (value > cutoff) {
+            return NGX_ERROR;
+        }
+
         value = value * 10;
     }
 
-    if (value < 0) {
-        return NGX_ERROR;
-
-    } else {
-        return value;
-    }
+    return value;
 }
 
 
 ssize_t
 ngx_atosz(u_char *line, size_t n)
 {
-    ssize_t  value;
+    ssize_t  value, cutoff, cutlim;
 
     if (n == 0) {
         return NGX_ERROR;
     }
 
+    cutoff = NGX_MAX_SIZE_T_VALUE / 10;
+    cutlim = NGX_MAX_SIZE_T_VALUE % 10;
+
     for (value = 0; n--; line++) {
         if (*line < '0' || *line > '9') {
             return NGX_ERROR;
         }
 
+        if (value >= cutoff && (value > cutoff || *line - '0' > cutlim)) {
+            return NGX_ERROR;
+        }
+
         value = value * 10 + (*line - '0');
     }
 
-    if (value < 0) {
-        return NGX_ERROR;
-
-    } else {
-        return value;
-    }
+    return value;
 }
 
 
 off_t
 ngx_atoof(u_char *line, size_t n)
 {
-    off_t  value;
+    off_t  value, cutoff, cutlim;
 
     if (n == 0) {
         return NGX_ERROR;
     }
 
+    cutoff = NGX_MAX_OFF_T_VALUE / 10;
+    cutlim = NGX_MAX_OFF_T_VALUE % 10;
+
     for (value = 0; n--; line++) {
         if (*line < '0' || *line > '9') {
             return NGX_ERROR;
         }
 
+        if (value >= cutoff && (value > cutoff || *line - '0' > cutlim)) {
+            return NGX_ERROR;
+        }
+
         value = value * 10 + (*line - '0');
     }
 
-    if (value < 0) {
-        return NGX_ERROR;
-
-    } else {
-        return value;
-    }
+    return value;
 }
 
 
 time_t
 ngx_atotm(u_char *line, size_t n)
 {
-    time_t  value;
+    time_t  value, cutoff, cutlim;
 
     if (n == 0) {
         return NGX_ERROR;
     }
 
+    cutoff = NGX_MAX_TIME_T_VALUE / 10;
+    cutlim = NGX_MAX_TIME_T_VALUE % 10;
+
     for (value = 0; n--; line++) {
         if (*line < '0' || *line > '9') {
             return NGX_ERROR;
         }
 
+        if (value >= cutoff && (value > cutoff || *line - '0' > cutlim)) {
+            return NGX_ERROR;
+        }
+
         value = value * 10 + (*line - '0');
     }
 
-    if (value < 0) {
-        return NGX_ERROR;
-
-    } else {
-        return value;
-    }
+    return value;
 }
 
 
@@ -1056,13 +1070,19 @@
 ngx_hextoi(u_char *line, size_t n)
 {
     u_char     c, ch;
-    ngx_int_t  value;
+    ngx_int_t  value, cutoff;
 
     if (n == 0) {
         return NGX_ERROR;
     }
 
+    cutoff = NGX_MAX_INT_T_VALUE / 16;
+
     for (value = 0; n--; line++) {
+        if (value > cutoff) {
+            return NGX_ERROR;
+        }
+
         ch = *line;
 
         if (ch >= '0' && ch <= '9') {
@@ -1080,12 +1100,7 @@
         return NGX_ERROR;
     }
 
-    if (value < 0) {
-        return NGX_ERROR;
-
-    } else {
-        return value;
-    }
+    return value;
 }