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Don't delete thread_info if refcount isn't zero
I build GDB with asan, and run test case hook-stop.exp, and threadapply.exp,
I got the following asan error,
=================================================================^M
^[[1m^[[31m==2291==ERROR: AddressSanitizer: heap-use-after-free on address 0x6160000999c4 at pc 0x000000826022 bp 0x7ffd28a8ff70 sp 0x7ffd28a8ff60^M
^[[1m^[[0m^[[1m^[[34mREAD of size 4 at 0x6160000999c4 thread T0^[[1m^[[0m^M
#0 0x826021 in release_stop_context_cleanup ../../binutils-gdb/gdb/infrun.c:8203^M
#1 0x72798a in do_my_cleanups ../../binutils-gdb/gdb/common/cleanups.c:154^M
#2 0x727a32 in do_cleanups(cleanup*) ../../binutils-gdb/gdb/common/cleanups.c:176^M
#3 0x826895 in normal_stop() ../../binutils-gdb/gdb/infrun.c:8381^M
#4 0x815208 in fetch_inferior_event(void*) ../../binutils-gdb/gdb/infrun.c:4011^M
#5 0x868aca in inferior_event_handler(inferior_event_type, void*) ../../binutils-gdb/gdb/inf-loop.c:44^M
....
^[[1m^[[32m0x6160000999c4 is located 68 bytes inside of 568-byte region [0x616000099980,0x616000099bb8)^M
^[[1m^[[0m^[[1m^[[35mfreed by thread T0 here:^[[1m^[[0m^M
#0 0x7fb0bc1312ca in __interceptor_free (/usr/lib/x86_64-linux-gnu/libasan.so.2+0x982ca)^M
#1 0xb8c62f in xfree(void*) ../../binutils-gdb/gdb/common/common-utils.c:100^M
#2 0x83df67 in free_thread ../../binutils-gdb/gdb/thread.c:207^M
#3 0x83dfd2 in init_thread_list() ../../binutils-gdb/gdb/thread.c:223^M
#4 0x805494 in kill_command ../../binutils-gdb/gdb/infcmd.c:2595^M
....
Detaching from program: /home/yao.qi/SourceCode/gnu/build-with-asan/gdb/testsuite/outputs/gdb.threads/threadapply/threadapply, process 2399^M
=================================================================^M
^[[1m^[[31m==2387==ERROR: AddressSanitizer: heap-use-after-free on address 0x6160000a98c0 at pc 0x00000083fd28 bp 0x7ffd401c3110 sp 0x7ffd401c3100^M
^[[1m^[[0m^[[1m^[[34mREAD of size 4 at 0x6160000a98c0 thread T0^[[1m^[[0m^M
#0 0x83fd27 in thread_alive ../../binutils-gdb/gdb/thread.c:741^M
#1 0x844277 in thread_apply_all_command ../../binutils-gdb/gdb/thread.c:1804^M
....
^M
^[[1m^[[32m0x6160000a98c0 is located 64 bytes inside of 568-byte region [0x6160000a9880,0x6160000a9ab8)^M
^[[1m^[[0m^[[1m^[[35mfreed by thread T0 here:^[[1m^[[0m^M
#0 0x7f59a7e322ca in __interceptor_free (/usr/lib/x86_64-linux-gnu/libasan.so.2+0x982ca)^M
#1 0xb8c62f in xfree(void*) ../../binutils-gdb/gdb/common/common-utils.c:100^M
#2 0x83df67 in free_thread ../../binutils-gdb/gdb/thread.c:207^M
#3 0x83dfd2 in init_thread_list() ../../binutils-gdb/gdb/thread.c:223^M
This patch fixes the issue by deleting thread_info object if it is
deletable, otherwise, mark it as exited (by set_thread_exited).
Function set_thread_exited is shared from delete_thread_1. This patch
also moves field "refcount" to private and methods incref and
decref. Additionally, we stop using "ptid_t" in
"struct current_thread_cleanup" to reference threads, instead we use
"thread_info" directly. Due to this change, we don't need
restore_current_thread_ptid_changed anymore.
gdb:
2017-04-10 Yao Qi <yao.qi@linaro.org>
PR gdb/19942
* gdbthread.h (thread_info::deletable): New method.
(thread_info::incref): New method.
(thread_info::decref): New method.
(thread_info::refcount): Move it to private.
* infrun.c (save_stop_context): Call inc_refcount.
(release_stop_context_cleanup): Likewise.
* thread.c (set_thread_exited): New function.
(init_thread_list): Delete "tp" only it is deletable, otherwise
call set_thread_exited.
(delete_thread_1): Call set_thread_exited.
(current_thread_cleanup) <inferior_pid>: Remove.
<thread>: New field.
(restore_current_thread_ptid_changed): Removed.
(do_restore_current_thread_cleanup): Adjust.
(restore_current_thread_cleanup_dtor): Don't call
find_thread_ptid.
(set_thread_refcount): Use dec_refcount.
(make_cleanup_restore_current_thread): Adjust.
(thread_apply_all_command): Call inc_refcount.
(_initialize_thread): Don't call
observer_attach_thread_ptid_changed.
This commit is contained in:
Yao Qi
parent
8c25b49760
commit
803bdfe430
@ -1,3 +1,28 @@
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2017-04-10 Yao Qi <yao.qi@linaro.org>
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PR gdb/19942
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* gdbthread.h (thread_info::deletable): New method.
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(thread_info::incref): New method.
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(thread_info::decref): New method.
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(thread_info::refcount): Move it to private.
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* infrun.c (save_stop_context): Call inc_refcount.
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(release_stop_context_cleanup): Likewise.
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* thread.c (set_thread_exited): New function.
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(init_thread_list): Delete "tp" only it is deletable, otherwise
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call set_thread_exited.
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(delete_thread_1): Call set_thread_exited.
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(current_thread_cleanup) <inferior_pid>: Remove.
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<thread>: New field.
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(restore_current_thread_ptid_changed): Removed.
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(do_restore_current_thread_cleanup): Adjust.
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(restore_current_thread_cleanup_dtor): Don't call
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find_thread_ptid.
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(set_thread_refcount): Use dec_refcount.
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(make_cleanup_restore_current_thread): Adjust.
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(thread_apply_all_command): Call inc_refcount.
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(_initialize_thread): Don't call
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observer_attach_thread_ptid_changed.
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2017-04-10 Yao Qi <yao.qi@linaro.org>
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* thread.c (delete_thread_1): Hoist code on marking thread as
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@ -183,6 +183,27 @@ public:
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explicit thread_info (inferior *inf, ptid_t ptid);
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~thread_info ();
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bool deletable () const
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{
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/* If this is the current thread, or there's code out there that
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relies on it existing (m_refcount > 0) we can't delete yet. */
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return (m_refcount == 0 && !ptid_equal (ptid, inferior_ptid));
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}
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/* Increase the refcount. */
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void incref ()
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{
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gdb_assert (m_refcount >= 0);
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m_refcount++;
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}
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/* Decrease the refcount. */
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void decref ()
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{
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m_refcount--;
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gdb_assert (m_refcount >= 0);
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}
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struct thread_info *next = NULL;
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ptid_t ptid; /* "Actual process id";
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In fact, this may be overloaded with
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@ -254,11 +275,6 @@ public:
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but STATE will still be THREAD_RUNNING. */
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enum thread_state state = THREAD_STOPPED;
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/* If this is > 0, then it means there's code out there that relies
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on this thread being listed. Don't delete it from the lists even
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if we detect it exiting. */
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int refcount = 0;
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/* State of GDB control of inferior thread execution.
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See `struct thread_control_state'. */
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thread_control_state control {};
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@ -346,6 +362,13 @@ public:
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fields point to self. */
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struct thread_info *step_over_prev = NULL;
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struct thread_info *step_over_next = NULL;
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private:
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/* If this is > 0, then it means there's code out there that relies
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on this thread being listed. Don't delete it from the lists even
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if we detect it exiting. */
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int m_refcount = 0;
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};
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/* Create an empty thread list, or empty the existing one. */
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@ -8165,7 +8165,7 @@ save_stop_context (void)
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/* Take a strong reference so that the thread can't be deleted
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yet. */
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sc->thread = inferior_thread ();
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sc->thread->refcount++;
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sc->thread->incref ();
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}
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else
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sc->thread = NULL;
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@ -8182,7 +8182,7 @@ release_stop_context_cleanup (void *arg)
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struct stop_context *sc = (struct stop_context *) arg;
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if (sc->thread != NULL)
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sc->thread->refcount--;
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sc->thread->decref ();
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xfree (sc);
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}
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101
gdb/thread.c
101
gdb/thread.c
@ -192,6 +192,27 @@ clear_thread_inferior_resources (struct thread_info *tp)
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thread_cancel_execution_command (tp);
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}
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/* Set the TP's state as exited. */
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static void
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set_thread_exited (thread_info *tp, int silent)
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{
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/* Dead threads don't need to step-over. Remove from queue. */
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if (tp->step_over_next != NULL)
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thread_step_over_chain_remove (tp);
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if (tp->state != THREAD_EXITED)
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{
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observer_notify_thread_exit (tp, silent);
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/* Tag it as exited. */
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tp->state = THREAD_EXITED;
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/* Clear breakpoints, etc. associated with this thread. */
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clear_thread_inferior_resources (tp);
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}
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}
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void
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init_thread_list (void)
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{
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@ -205,7 +226,10 @@ init_thread_list (void)
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for (tp = thread_list; tp; tp = tpnext)
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{
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tpnext = tp->next;
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delete tp;
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if (tp->deletable ())
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delete tp;
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else
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set_thread_exited (tp, 1);
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}
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thread_list = NULL;
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@ -430,25 +454,9 @@ delete_thread_1 (ptid_t ptid, int silent)
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if (!tp)
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return;
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/* Dead threads don't need to step-over. Remove from queue. */
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if (tp->step_over_next != NULL)
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thread_step_over_chain_remove (tp);
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set_thread_exited (tp, silent);
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if (tp->state != THREAD_EXITED)
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{
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observer_notify_thread_exit (tp, silent);
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/* Tag it as exited. */
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tp->state = THREAD_EXITED;
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/* Clear breakpoints, etc. associated with this thread. */
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clear_thread_inferior_resources (tp);
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}
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/* If this is the current thread, or there's code out there that
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relies on it existing (refcount > 0) we can't delete yet. */
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if (tp->refcount > 0
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|| ptid_equal (tp->ptid, inferior_ptid))
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if (!tp->deletable ())
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{
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/* Will be really deleted some other time. */
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return;
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@ -1546,7 +1554,7 @@ struct current_thread_cleanup
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'current_thread_cleanup_chain' below. */
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struct current_thread_cleanup *next;
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ptid_t inferior_ptid;
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thread_info *thread;
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struct frame_id selected_frame_id;
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int selected_frame_level;
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int was_stopped;
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@ -1561,37 +1569,21 @@ struct current_thread_cleanup
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succeeds. */
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static struct current_thread_cleanup *current_thread_cleanup_chain;
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/* A thread_ptid_changed observer. Update all currently installed
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current_thread_cleanup cleanups that want to switch back to
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OLD_PTID to switch back to NEW_PTID instead. */
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static void
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restore_current_thread_ptid_changed (ptid_t old_ptid, ptid_t new_ptid)
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{
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struct current_thread_cleanup *it;
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for (it = current_thread_cleanup_chain; it != NULL; it = it->next)
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{
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if (ptid_equal (it->inferior_ptid, old_ptid))
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it->inferior_ptid = new_ptid;
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}
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}
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static void
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do_restore_current_thread_cleanup (void *arg)
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{
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struct thread_info *tp;
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struct current_thread_cleanup *old = (struct current_thread_cleanup *) arg;
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tp = find_thread_ptid (old->inferior_ptid);
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/* If the previously selected thread belonged to a process that has
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in the mean time been deleted (due to normal exit, detach, etc.),
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then don't revert back to it, but instead simply drop back to no
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thread selected. */
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if (tp
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&& find_inferior_ptid (tp->ptid) != NULL)
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restore_current_thread (old->inferior_ptid);
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/* If an entry of thread_info was previously selected, it won't be
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deleted because we've increased its refcount. The thread represented
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by this thread_info entry may have already exited (due to normal exit,
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detach, etc), so the thread_info.state is THREAD_EXITED. */
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if (old->thread != NULL
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/* If the previously selected thread belonged to a process that has
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in the mean time exited (or killed, detached, etc.), then don't revert
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back to it, but instead simply drop back to no thread selected. */
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&& find_inferior_ptid (old->thread->ptid) != NULL)
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restore_current_thread (old->thread->ptid);
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else
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{
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restore_current_thread (null_ptid);
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@ -1619,9 +1611,9 @@ restore_current_thread_cleanup_dtor (void *arg)
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current_thread_cleanup_chain = current_thread_cleanup_chain->next;
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tp = find_thread_ptid (old->inferior_ptid);
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if (tp)
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tp->refcount--;
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if (old->thread != NULL)
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old->thread->decref ();
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inf = find_inferior_id (old->inf_id);
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if (inf != NULL)
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inf->removable = old->was_removable;
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@ -1638,7 +1630,7 @@ set_thread_refcount (void *data)
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= (struct thread_array_cleanup *) data;
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for (k = 0; k != ta_cleanup->count; k++)
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ta_cleanup->tp_array[k]->refcount--;
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ta_cleanup->tp_array[k]->decref ();
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}
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struct cleanup *
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@ -1646,7 +1638,7 @@ make_cleanup_restore_current_thread (void)
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{
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struct current_thread_cleanup *old = XNEW (struct current_thread_cleanup);
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old->inferior_ptid = inferior_ptid;
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old->thread = NULL;
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old->inf_id = current_inferior ()->num;
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old->was_removable = current_inferior ()->removable;
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@ -1679,7 +1671,8 @@ make_cleanup_restore_current_thread (void)
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struct thread_info *tp = find_thread_ptid (inferior_ptid);
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if (tp)
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tp->refcount++;
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tp->incref ();
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old->thread = tp;
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}
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current_inferior ()->removable = 0;
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@ -1796,7 +1789,7 @@ thread_apply_all_command (char *cmd, int from_tty)
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ALL_NON_EXITED_THREADS (tp)
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{
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tp_array[i] = tp;
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tp->refcount++;
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tp->incref ();
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i++;
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}
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/* Because we skipped exited threads, we may end up with fewer
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@ -2286,6 +2279,4 @@ Show printing of thread events (such as thread start and exit)."), NULL,
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create_internalvar_type_lazy ("_thread", &thread_funcs, NULL);
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create_internalvar_type_lazy ("_gthread", >hread_funcs, NULL);
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observer_attach_thread_ptid_changed (restore_current_thread_ptid_changed);
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}
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