detect/content: simplify int bounds checking

Use a macro to validate the ranges for overflows. This removes
the clutter of all the checks and warnings, and also no longer
puts the state machine in an undefined state when hitting such
a condition.

(cherry picked from commit 50d02ebc055ac99db9ea565ed7bd623c357cceb0)

diff --git a/src/detect-content.c b/src/detect-content.c
index ccdfffb9ea4cf69d0f9bc89b27b850636450694a..05304b2449a52fca38fb97a368b567de462f28d8 100644 (file)
--- a/src/detect-content.c
+++ b/src/detect-content.c
@@ -441,6 +441,10 @@ _Bool DetectContentPMATCHValidateCallback(const Signature *s)
  */
 void DetectContentPropagateLimits(Signature *s)
 {
+#define VALIDATE(e)                                                                                \
+    if (!(e)) {                                                                                    \
+        return;                                                                                    \
+    }
     BUG_ON(s == NULL || s->init_data == NULL);
 
     uint32_t list = 0;
@@ -501,11 +505,8 @@ void DetectContentPropagateLimits(Signature *s)
                     SCLogDebug("stored: offset %u depth %u offset_plus_pat %u", offset, depth, offset_plus_pat);
 
                     if (cd->flags & DETECT_CONTENT_DISTANCE && cd->distance >= 0) {
-                        if ((uint32_t)offset_plus_pat + cd->distance <= UINT16_MAX) {
-                            offset = cd->offset = (uint16_t)(offset_plus_pat + cd->distance);
-                        } else {
-                            SCLogDebug("not updated content offset as it would overflow : %u + %d", offset_plus_pat, cd->distance);
-                        }
+                        VALIDATE((uint32_t)offset_plus_pat + cd->distance <= UINT16_MAX);
+                        offset = cd->offset = (uint16_t)(offset_plus_pat + cd->distance);
                         SCLogDebug("updated content to have offset %u", cd->offset);
                     }
                     if (have_anchor && !last_reset && offset_plus_pat && cd->flags & DETECT_CONTENT_WITHIN && cd->within >= 0) {
@@ -516,23 +517,13 @@ void DetectContentPropagateLimits(Signature *s)
                                 SCLogDebug("distance to add: %u. depth + dist %u", dist, depth + dist);
                             }
                             SCLogDebug("depth %u + cd->within %u", depth, cd->within);
-                            if (depth + cd->within + dist < 0 ||
-                                    depth + cd->within + dist > UINT16_MAX) {
-                                SCLogDebug("not updated content depth as it would overflow : %u + "
-                                           "%d + %u",
-                                        depth, cd->within, dist);
-                            } else {
-                                depth = cd->depth = (uint16_t)(depth + cd->within + dist);
-                            }
+                            VALIDATE(depth + cd->within + dist >= 0 &&
+                                     depth + cd->within + dist <= UINT16_MAX);
+                            depth = cd->depth = (uint16_t)(depth + cd->within + dist);
                         } else {
                             SCLogDebug("offset %u + cd->within %u", offset, cd->within);
-                            if (depth + cd->within < 0 || depth + cd->within > UINT16_MAX) {
-                                SCLogDebug(
-                                        "not updated content depth as it would overflow : %u + %d",
-                                        offset, cd->within);
-                            } else {
-                                depth = cd->depth = (uint16_t)(offset + cd->within);
-                            }
+                            VALIDATE(depth + cd->within >= 0 && depth + cd->within <= UINT16_MAX);
+                            depth = cd->depth = (uint16_t)(offset + cd->within);
                         }
                         SCLogDebug("updated content to have depth %u", cd->depth);
                     } else {
@@ -540,25 +531,15 @@ void DetectContentPropagateLimits(Signature *s)
                             if (cd->within > 0) {
                                 SCLogDebug("within %d distance %d", cd->within, cd->distance);
                                 if (cd->flags & DETECT_CONTENT_DISTANCE && cd->distance >= 0) {
-                                    if (offset_plus_pat + cd->distance < 0 ||
-                                            offset_plus_pat + cd->distance > UINT16_MAX) {
-                                        SCLogDebug("not updated content offset as it would "
-                                                   "overflow : %u + %d",
-                                                offset_plus_pat, cd->distance);
-                                    } else {
-                                        cd->offset = (uint16_t)(offset_plus_pat + cd->distance);
-                                    }
+                                    VALIDATE(offset_plus_pat + cd->distance >= 0 &&
+                                             offset_plus_pat + cd->distance <= UINT16_MAX);
+                                    cd->offset = (uint16_t)(offset_plus_pat + cd->distance);
                                     SCLogDebug("updated content to have offset %u", cd->offset);
                                 }
 
-                                if (depth + cd->within < 0 || depth + cd->within > UINT16_MAX) {
-                                    SCLogDebug("not updated content depth as it would overflow : "
-                                               "%u + %d",
-                                            offset, cd->within);
-                                } else {
-                                    cd->depth = (uint16_t)(cd->within + depth);
-                                }
-                                depth = cd->depth;
+                                VALIDATE(depth + cd->within >= 0 &&
+                                         depth + cd->within <= UINT16_MAX);
+                                depth = cd->depth = (uint16_t)(cd->within + depth);
                                 SCLogDebug("updated content to have depth %u", cd->depth);
 
                                 if (cd->flags & DETECT_CONTENT_ENDS_WITH) {
@@ -581,11 +562,8 @@ void DetectContentPropagateLimits(Signature *s)
                             (cd->flags & (DETECT_CONTENT_DEPTH|DETECT_CONTENT_OFFSET|DETECT_CONTENT_WITHIN|DETECT_CONTENT_DISTANCE)) == (DETECT_CONTENT_DISTANCE)) {
                         if (cd->distance >= 0) {
                             // only distance
-                            if ((uint32_t)offset_plus_pat + cd->distance <= UINT16_MAX) {
-                                offset = cd->offset = (uint16_t)(offset_plus_pat + cd->distance);
-                            } else {
-                                SCLogDebug("not updated content offset as it would overflow : %u + %d", offset_plus_pat, cd->distance);
-                            }
+                            VALIDATE((uint32_t)offset_plus_pat + cd->distance <= UINT16_MAX);
+                            offset = cd->offset = (uint16_t)(offset_plus_pat + cd->distance);
                             offset_plus_pat = offset + cd->content_len;
                             SCLogDebug("offset %u offset_plus_pat %u", offset, offset_plus_pat);
                         }
@@ -653,6 +631,7 @@ void DetectContentPropagateLimits(Signature *s)
             }
         }
     }
+#undef VALIDATE
 }
 
 #ifdef UNITTESTS /* UNITTESTS */
@@ -750,7 +729,8 @@ static int DetectContentDepthTest01(void)
     // hi end: depth '13' (4+9) + distance 55 = 68 + within 2 = 70
     TEST_RUN("content:\"=\"; offset:4; depth:9; content:\"=&\"; distance:55; within:2;", 60, 70);
 
-    TEST_RUN("content:\"0123456789\"; content:\"abcdef\"; distance:2147483647;", 10, 0);
+    // distance value is too high so we bail and not set anything on this content
+    TEST_RUN("content:\"0123456789\"; content:\"abcdef\"; distance:2147483647;", 0, 0);
 
     TEST_DONE;
 }