From 50d02ebc055ac99db9ea565ed7bd623c357cceb0 Mon Sep 17 00:00:00 2001 From: Victor Julien Date: Thu, 9 Jun 2022 22:25:08 +0200 Subject: [PATCH] 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. --- src/detect-content.c | 64 +++++++++++++++----------------------------- 1 file changed, 22 insertions(+), 42 deletions(-) diff --git a/src/detect-content.c b/src/detect-content.c index 47f9de452b..e491b47414 100644 --- a/src/detect-content.c +++ b/src/detect-content.c @@ -445,6 +445,10 @@ 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; @@ -505,11 +509,8 @@ 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) { @@ -520,23 +521,13 @@ 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 { @@ -544,25 +535,15 @@ 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) { @@ -585,11 +566,8 @@ 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); } @@ -657,6 +635,7 @@ void DetectContentPropagateLimits(Signature *s) } } } +#undef VALIDATE } static inline bool NeedsAsHex(uint8_t c) @@ -798,7 +777,8 @@ 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; }