From 671a283636de75f7ed638ee6b01ed2d44361b8b6 Mon Sep 17 00:00:00 2001
From: Martin Sebor <msebor@redhat.com>
Date: Sat, 15 Jan 2022 16:37:54 -0700
Subject: Add -Wuse-after-free [PR80532].

gcc/c-family/ChangeLog

	PR tree-optimization/80532
	* c.opt (-Wuse-after-free): New options.

gcc/ChangeLog:

	PR tree-optimization/80532
	* common.opt (-Wuse-after-free): New options.
	* diagnostic-spec.c (nowarn_spec_t::nowarn_spec_t): Handle
	OPT_Wreturn_local_addr and OPT_Wuse_after_free_.
	* diagnostic-spec.h (NW_DANGLING): New enumerator.
	* doc/invoke.texi (-Wuse-after-free): Document new option.
	* gimple-ssa-warn-access.cc (pass_waccess::check_call): Rename...
	(pass_waccess::check_call_access): ...to this.
	(pass_waccess::check): Rename...
	(pass_waccess::check_block): ...to this.
	(pass_waccess::check_pointer_uses): New function.
	(pass_waccess::gimple_call_return_arg): New function.
	(pass_waccess::warn_invalid_pointer): New function.
	(pass_waccess::check_builtin): Handle free and realloc.
	(gimple_use_after_inval_p): New function.
	(get_realloc_lhs): New function.
	(maybe_warn_mismatched_realloc): New function.
	(pointers_related_p): New function.
	(pass_waccess::check_call): Call check_pointer_uses.
	(pass_waccess::execute): Compute and free dominance info.

libcpp/ChangeLog:

	* files.c (_cpp_find_file): Substitute a valid pointer for
	an invalid one to avoid -Wuse-after-free.

libiberty/ChangeLog:

	* regex.c: Suppress -Wuse-after-free.

gcc/testsuite/ChangeLog:

	PR tree-optimization/80532
	* gcc.dg/Wmismatched-dealloc-2.c: Avoid -Wuse-after-free.
	* gcc.dg/Wmismatched-dealloc-3.c: Same.
	* gcc.dg/analyzer/file-1.c: Prune expected warning.
	* gcc.dg/analyzer/file-2.c: Same.
	* gcc.dg/attr-alloc_size-6.c: Disable -Wuse-after-free.
	* gcc.dg/attr-alloc_size-7.c: Same.
	* c-c++-common/Wuse-after-free-2.c: New test.
	* c-c++-common/Wuse-after-free-3.c: New test.
	* c-c++-common/Wuse-after-free-4.c: New test.
	* c-c++-common/Wuse-after-free-5.c: New test.
	* c-c++-common/Wuse-after-free-6.c: New test.
	* c-c++-common/Wuse-after-free-7.c: New test.
	* c-c++-common/Wuse-after-free.c: New test.
	* g++.dg/warn/Wmismatched-dealloc-3.C: New test.
	* g++.dg/warn/Wuse-after-free.C: New test.
---
 libcpp/files.c | 13 ++++++-------
 1 file changed, 6 insertions(+), 7 deletions(-)

(limited to 'libcpp/files.c')

diff --git a/libcpp/files.c b/libcpp/files.c
index e4e234f..24208f7 100644
--- a/libcpp/files.c
+++ b/libcpp/files.c
@@ -553,12 +553,11 @@ _cpp_find_file (cpp_reader *pfile, const char *fname, cpp_dir *start_dir,
 		  {
 		    /* If *hash_slot is NULL, the above
 		       htab_find_slot_with_hash call just created the
-		       slot, but we aren't going to store there
-		       anything, so need to remove the newly created
-		       entry.  htab_clear_slot requires that it is
-		       non-NULL, so store there some non-NULL pointer,
-		       htab_clear_slot will overwrite it
-		       immediately.  */
+		       slot, but we aren't going to store there anything
+		       of use, so need to remove the newly created entry.
+		       htab_clear_slot requires that it is non-NULL, so
+		       store some non-NULL but valid pointer there,
+		       htab_clear_slot will immediately overwrite it.  */
 		    *hash_slot = file;
 		    htab_clear_slot (pfile->file_hash, hash_slot);
 		  }
@@ -582,7 +581,7 @@ _cpp_find_file (cpp_reader *pfile, const char *fname, cpp_dir *start_dir,
 		if (*hash_slot == NULL)
 		  {
 		    /* See comment on the above htab_clear_slot call.  */
-		    *hash_slot = file;
+		    *hash_slot = &hash_slot;
 		    htab_clear_slot (pfile->file_hash, hash_slot);
 		  }
 		return NULL;
-- 
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