[binutils-gdb] Fix heap-use-after-free in index-cached with --disable-threading

[binutils-gdb] Fix heap-use-after-free in index-cached with --disable-threading

[Hannes Domani]

https://sourceware.org/git/gitweb.cgi?p=binutils-gdb.git;h=5140d8e013b0d8ab560b1bb8c72e0a8b2e96ac4b

commit 5140d8e013b0d8ab560b1bb8c72e0a8b2e96ac4b
Author: Hannes Domani <ssbssa@yahoo.de>
Date:   Sat May 4 18:55:20 2024 +0200

    Fix heap-use-after-free in index-cached with --disable-threading
    
    If threads are disabled, either by --disable-threading explicitely, or by
    missing std::thread support, you get the following ASAN error when
    loading symbols:
    
    ==7310==ERROR: AddressSanitizer: heap-use-after-free on address 0x614000002128 at pc 0x00000098794a bp 0x7ffe37e6af70 sp 0x7ffe37e6af68
    READ of size 1 at 0x614000002128 thread T0
        #0 0x987949 in index_cache_store_context::store() const ../../gdb/dwarf2/index-cache.c:163
        #1 0x943467 in cooked_index_worker::write_to_cache(cooked_index const*, deferred_warnings*) const ../../gdb/dwarf2/cooked-index.c:601
        #2 0x1705e39 in std::function<void ()>::operator()() const /gcc/9/include/c++/9.2.0/bits/std_function.h:690
        #3 0x1705e39 in gdb::task_group::impl::~impl() ../../gdbsupport/task-group.cc:38
    
    0x614000002128 is located 232 bytes inside of 408-byte region [0x614000002040,0x6140000021d8)
    freed by thread T0 here:
        #0 0x7fd75ccf8ea5 in operator delete(void*, unsigned long) ../../.././libsanitizer/asan/asan_new_delete.cc:177
        #1 0x9462e5 in cooked_index::index_for_writing() ../../gdb/dwarf2/cooked-index.h:689
        #2 0x9462e5 in operator() ../../gdb/dwarf2/cooked-index.c:657
        #3 0x9462e5 in _M_invoke /gcc/9/include/c++/9.2.0/bits/std_function.h:300
    
    It's happening because cooked_index_worker::wait always returns true in
    this case, which tells cooked_index::wait it can delete the m_state
    cooked_index_worker member, but cooked_index_worker::write_to_cache tries
    to access it immediately afterwards.
    
    Fixed by making cooked_index_worker::wait only return true if desired_state
    is CACHE_DONE, same as if threading was enabled, so m_state will not be
    prematurely deleted.
    
    Bug: https://sourceware.org/bugzilla/show_bug.cgi?id=31694
    Approved-By: Tom Tromey <tom@tromey.com>

Diff:
---
 gdb/dwarf2/cooked-index.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/gdb/dwarf2/cooked-index.c b/gdb/dwarf2/cooked-index.c
index 3b95c075a55..767f119e04f 100644
--- a/gdb/dwarf2/cooked-index.c
+++ b/gdb/dwarf2/cooked-index.c
@@ -513,7 +513,7 @@ cooked_index_worker::wait (cooked_state desired_state, bool allow_quit)
 #else
   /* Without threads, all the work is done immediately on the main
      thread, and there is never anything to wait for.  */
-  done = true;
+  done = desired_state == cooked_state::CACHE_DONE;
 #endif /* CXX_STD_THREAD */
 
   /* Only the main thread is allowed to report complaints and the