From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: by sourceware.org (Postfix, from userid 2209) id 29BDE3858022; Wed, 24 Jan 2024 15:12:36 +0000 (GMT) DKIM-Filter: OpenDKIM Filter v2.11.0 sourceware.org 29BDE3858022 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gcc.gnu.org; s=default; t=1706109156; bh=poA+SzU/vabAUecK+4lk7paINQLnXTwhIUF1QAdPxVg=; h=From:To:Subject:Date:From; b=Y2MaJLBdAKALkXa3bRnruMzqOyXWg7Msn0n9uOz5OCueyry/ouqrIq4X0qNt+xva7 qU6hRA0esbrDH874mV+AeyoKLjiesJ94uwYiGKRsT1/fgHMxAJZG8hGN+hQ2nuNvp3 BylFHJH5Kykgtt2wQYFmelcALc3iM4ZCjf3D8vvc= MIME-Version: 1.0 Content-Transfer-Encoding: 7bit Content-Type: text/plain; charset="utf-8" From: David Malcolm To: gcc-cvs@gcc.gnu.org Subject: [gcc r14-8391] analyzer: fix taint false +ve due to overzealous state purging [PR112977] X-Act-Checkin: gcc X-Git-Author: David Malcolm X-Git-Refname: refs/heads/master X-Git-Oldrev: b6e537571c21d8f0bc276d7afa156d6d4a54a1c9 X-Git-Newrev: e503f9aca9192654d83f141ae7865a3c9d90bf0d Message-Id: <20240124151236.29BDE3858022@sourceware.org> Date: Wed, 24 Jan 2024 15:12:36 +0000 (GMT) List-Id: https://gcc.gnu.org/g:e503f9aca9192654d83f141ae7865a3c9d90bf0d commit r14-8391-ge503f9aca9192654d83f141ae7865a3c9d90bf0d Author: David Malcolm Date: Wed Jan 24 10:11:35 2024 -0500 analyzer: fix taint false +ve due to overzealous state purging [PR112977] gcc/analyzer/ChangeLog: PR analyzer/112977 * engine.cc (impl_region_model_context::on_liveness_change): Pass m_ext_state to sm_state_map::on_liveness_change. * program-state.cc (sm_state_map::on_svalue_leak): Guard removal of map entry based on can_purge_p. (sm_state_map::on_liveness_change): Add ext_state param. Add workaround for bad interaction between state purging and alt-inherited sm-state. * program-state.h (sm_state_map::on_liveness_change): Add ext_state param. * sm-taint.cc (taint_state_machine::has_alt_get_inherited_state_p): New. (taint_state_machine::can_purge_p): Return false for "has_lb" and "has_ub". * sm.h (state_machine::has_alt_get_inherited_state_p): New vfunc. gcc/testsuite/ChangeLog: PR analyzer/112977 * gcc.dg/plugin/plugin.exp: Add taint-pr112977.c. * gcc.dg/plugin/taint-pr112977.c: New test. Signed-off-by: David Malcolm Diff: --- gcc/analyzer/engine.cc | 2 +- gcc/analyzer/program-state.cc | 65 +++++++++++++++++++++++++++- gcc/analyzer/program-state.h | 1 + gcc/analyzer/sm-taint.cc | 9 ++++ gcc/analyzer/sm.h | 6 +++ gcc/testsuite/gcc.dg/plugin/plugin.exp | 3 +- gcc/testsuite/gcc.dg/plugin/taint-pr112977.c | 44 +++++++++++++++++++ 7 files changed, 126 insertions(+), 4 deletions(-) diff --git a/gcc/analyzer/engine.cc b/gcc/analyzer/engine.cc index fde8412bc15..44ff20cf9af 100644 --- a/gcc/analyzer/engine.cc +++ b/gcc/analyzer/engine.cc @@ -179,7 +179,7 @@ on_liveness_change (const svalue_set &live_svalues, const region_model *model) { for (sm_state_map *smap : m_new_state->m_checker_states) - smap->on_liveness_change (live_svalues, model, this); + smap->on_liveness_change (live_svalues, model, m_ext_state, this); } void diff --git a/gcc/analyzer/program-state.cc b/gcc/analyzer/program-state.cc index 888f2a9c40b..55dd6ca7166 100644 --- a/gcc/analyzer/program-state.cc +++ b/gcc/analyzer/program-state.cc @@ -560,9 +560,10 @@ sm_state_map::on_svalue_leak (const svalue *sval, { if (state_machine::state_t state = get_state (sval, ctxt->m_ext_state)) { - if (!m_sm.can_purge_p (state)) + if (m_sm.can_purge_p (state)) + m_map.remove (sval); + else ctxt->on_state_leak (m_sm, sval, state); - m_map.remove (sval); } } @@ -572,6 +573,7 @@ sm_state_map::on_svalue_leak (const svalue *sval, void sm_state_map::on_liveness_change (const svalue_set &live_svalues, const region_model *model, + const extrinsic_state &ext_state, impl_region_model_context *ctxt) { svalue_set svals_to_unset; @@ -605,9 +607,68 @@ sm_state_map::on_liveness_change (const svalue_set &live_svalues, ctxt->on_state_leak (m_sm, sval, e.m_state); } + sm_state_map old_sm_map = *this; + for (svalue_set::iterator iter = svals_to_unset.begin (); iter != svals_to_unset.end (); ++iter) m_map.remove (*iter); + + /* For state machines like "taint" where states can be + alt-inherited from other svalues, ensure that state purging doesn't + make us lose sm-state. + + Consider e.g.: + + make_tainted(foo); + if (foo.field > 128) + return; + arr[foo.field].f1 = v1; + + where the last line is: + + (A): _t1 = foo.field; + (B): _t2 = _t1 * sizeof(arr[0]); + (C): [arr + _t2].f1 = val; + + At (A), foo is 'tainted' and foo.field is 'has_ub'. + After (B), foo.field's value (in _t1) is no longer directly + within LIVE_SVALUES, so with state purging enabled, we would + erroneously purge the "has_ub" state from the svalue. + + Given that _t2's value's state comes from _t1's value's state, + we need to preserve that information. + + Hence for all svalues that have had their explicit sm-state unset, + having their sm-state being unset, determine if doing so has changed + their effective state, and if so, explicitly set their state. + + For example, in the above, unsetting the "has_ub" for _t1's value means + that _t2's effective value changes from "has_ub" (from alt-inherited + from _t1's value) to "tainted" (inherited from "foo"'s value). + + For such cases, preserve the effective state by explicitly setting the + new state. In the above example, this means explicitly setting _t2's + value to the value ("has_ub") it was previously alt-inheriting from _t1's + value. */ + if (m_sm.has_alt_get_inherited_state_p ()) + { + auto_vec svalues_needing_state; + for (auto unset_sval : svals_to_unset) + { + const state_machine::state_t old_state + = old_sm_map.get_state (unset_sval, ext_state); + const state_machine::state_t new_state + = get_state (unset_sval, ext_state); + if (new_state != old_state) + svalues_needing_state.safe_push (unset_sval); + } + for (auto sval : svalues_needing_state) + { + const state_machine::state_t old_state + = old_sm_map.get_state (sval, ext_state); + impl_set_state (sval, old_state, nullptr, ext_state); + } + } } /* Purge state from SVAL (in response to a call to an unknown function). */ diff --git a/gcc/analyzer/program-state.h b/gcc/analyzer/program-state.h index 50bf2ab277a..69bf931f070 100644 --- a/gcc/analyzer/program-state.h +++ b/gcc/analyzer/program-state.h @@ -155,6 +155,7 @@ public: impl_region_model_context *ctxt); void on_liveness_change (const svalue_set &live_svalues, const region_model *model, + const extrinsic_state &ext_state, impl_region_model_context *ctxt); void on_unknown_change (const svalue *sval, diff --git a/gcc/analyzer/sm-taint.cc b/gcc/analyzer/sm-taint.cc index dc4b078c411..bbf683f82ef 100644 --- a/gcc/analyzer/sm-taint.cc +++ b/gcc/analyzer/sm-taint.cc @@ -86,6 +86,12 @@ public: const extrinsic_state &ext_state) const final override; + bool + has_alt_get_inherited_state_p () const final override + { + return true; + } + bool on_stmt (sm_context *sm_ctxt, const supernode *node, const gimple *stmt) const final override; @@ -1199,6 +1205,9 @@ taint_state_machine::on_bounded_ranges (sm_context *sm_ctxt, bool taint_state_machine::can_purge_p (state_t s ATTRIBUTE_UNUSED) const { + if (s == m_has_lb || s == m_has_ub) + return false; + return true; } diff --git a/gcc/analyzer/sm.h b/gcc/analyzer/sm.h index e7f634f4245..a58f5dbc395 100644 --- a/gcc/analyzer/sm.h +++ b/gcc/analyzer/sm.h @@ -78,6 +78,12 @@ public: return NULL; } + virtual bool + has_alt_get_inherited_state_p () const + { + return false; + } + virtual state_machine::state_t get_default_state (const svalue *) const { return m_start; diff --git a/gcc/testsuite/gcc.dg/plugin/plugin.exp b/gcc/testsuite/gcc.dg/plugin/plugin.exp index a5a72daac1a..8141cc2aa46 100644 --- a/gcc/testsuite/gcc.dg/plugin/plugin.exp +++ b/gcc/testsuite/gcc.dg/plugin/plugin.exp @@ -170,7 +170,8 @@ set plugin_test_list [list \ taint-pr112850-precise.c \ taint-pr112850-too-complex.c \ taint-pr112850-unsanitized.c \ - taint-pr112927.c } \ + taint-pr112927.c \ + taint-pr112977.c } \ { analyzer_cpython_plugin.c \ cpython-plugin-test-no-Python-h.c \ cpython-plugin-test-PyList_Append.c \ diff --git a/gcc/testsuite/gcc.dg/plugin/taint-pr112977.c b/gcc/testsuite/gcc.dg/plugin/taint-pr112977.c new file mode 100644 index 00000000000..a9beb00b88d --- /dev/null +++ b/gcc/testsuite/gcc.dg/plugin/taint-pr112977.c @@ -0,0 +1,44 @@ +/* Reduced from false positive in Linux kernel in + drivers/scsi/aacraid/aachba.c. */ + +/* { dg-do compile } */ +/* { dg-options "-fanalyzer" } */ +/* { dg-require-effective-target analyzer } */ + +typedef unsigned char u8; +typedef unsigned int u32; + +extern unsigned long +copy_from_user(void* to, const void* from, unsigned long n); + +struct fsa_dev_info +{ + u8 valid; + u8 deleted; +}; +struct aac_dev +{ + int maximum_num_containers; + struct fsa_dev_info* fsa_dev; +}; +struct aac_delete_disk +{ + u32 disknum; + u32 cnum; +}; +int +force_delete_disk(struct aac_dev* dev, void* arg) +{ + struct aac_delete_disk dd; + struct fsa_dev_info* fsa_dev_ptr; + fsa_dev_ptr = dev->fsa_dev; + if (!fsa_dev_ptr) + return -16; + if (copy_from_user(&dd, arg, sizeof(struct aac_delete_disk))) + return -14; + if (dd.cnum >= dev->maximum_num_containers) + return -22; + fsa_dev_ptr[dd.cnum].deleted = 1; + fsa_dev_ptr[dd.cnum].valid = 0; /* { dg-bogus "use of attacker-controlled value as offset without upper-bounds checking" } */ + return 0; +}