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authorYao Qi <yao.qi@linaro.org>2017-04-10 14:39:41 +0100
committerYao Qi <yao.qi@linaro.org>2017-04-10 14:39:41 +0100
commit803bdfe43083475c7df3db38dc96f4e20d05457d (patch)
treea07c0036f9ff54f9be271361b0e9260657541cff /gdb
parent8c25b49760b854d0b8451e8ecffeb9860fc41158 (diff)
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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.
Diffstat (limited to 'gdb')
-rw-r--r--gdb/ChangeLog25
-rw-r--r--gdb/gdbthread.h33
-rw-r--r--gdb/infrun.c4
-rw-r--r--gdb/thread.c101
4 files changed, 101 insertions, 62 deletions
diff --git a/gdb/ChangeLog b/gdb/ChangeLog
index a1f8b49..68d8f34 100644
--- a/gdb/ChangeLog
+++ b/gdb/ChangeLog
@@ -1,5 +1,30 @@
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.
+
+2017-04-10 Yao Qi <yao.qi@linaro.org>
+
* thread.c (delete_thread_1): Hoist code on marking thread as
exited.
diff --git a/gdb/gdbthread.h b/gdb/gdbthread.h
index 9a16fe6..4cd7390 100644
--- a/gdb/gdbthread.h
+++ b/gdb/gdbthread.h
@@ -183,6 +183,27 @@ public:
explicit thread_info (inferior *inf, ptid_t ptid);
~thread_info ();
+ bool deletable () const
+ {
+ /* If this is the current thread, or there's code out there that
+ relies on it existing (m_refcount > 0) we can't delete yet. */
+ return (m_refcount == 0 && !ptid_equal (ptid, inferior_ptid));
+ }
+
+ /* Increase the refcount. */
+ void incref ()
+ {
+ gdb_assert (m_refcount >= 0);
+ m_refcount++;
+ }
+
+ /* Decrease the refcount. */
+ void decref ()
+ {
+ m_refcount--;
+ gdb_assert (m_refcount >= 0);
+ }
+
struct thread_info *next = NULL;
ptid_t ptid; /* "Actual process id";
In fact, this may be overloaded with
@@ -254,11 +275,6 @@ public:
but STATE will still be THREAD_RUNNING. */
enum thread_state state = THREAD_STOPPED;
- /* If this is > 0, then it means there's code out there that relies
- on this thread being listed. Don't delete it from the lists even
- if we detect it exiting. */
- int refcount = 0;
-
/* State of GDB control of inferior thread execution.
See `struct thread_control_state'. */
thread_control_state control {};
@@ -346,6 +362,13 @@ public:
fields point to self. */
struct thread_info *step_over_prev = NULL;
struct thread_info *step_over_next = NULL;
+
+private:
+
+ /* If this is > 0, then it means there's code out there that relies
+ on this thread being listed. Don't delete it from the lists even
+ if we detect it exiting. */
+ int m_refcount = 0;
};
/* Create an empty thread list, or empty the existing one. */
diff --git a/gdb/infrun.c b/gdb/infrun.c
index c8c2d6e..b5eb4ab 100644
--- a/gdb/infrun.c
+++ b/gdb/infrun.c
@@ -8165,7 +8165,7 @@ save_stop_context (void)
/* Take a strong reference so that the thread can't be deleted
yet. */
sc->thread = inferior_thread ();
- sc->thread->refcount++;
+ sc->thread->incref ();
}
else
sc->thread = NULL;
@@ -8182,7 +8182,7 @@ release_stop_context_cleanup (void *arg)
struct stop_context *sc = (struct stop_context *) arg;
if (sc->thread != NULL)
- sc->thread->refcount--;
+ sc->thread->decref ();
xfree (sc);
}
diff --git a/gdb/thread.c b/gdb/thread.c
index 2e9da53..2d936cd 100644
--- a/gdb/thread.c
+++ b/gdb/thread.c
@@ -192,6 +192,27 @@ clear_thread_inferior_resources (struct thread_info *tp)
thread_cancel_execution_command (tp);
}
+/* Set the TP's state as exited. */
+
+static void
+set_thread_exited (thread_info *tp, int silent)
+{
+ /* Dead threads don't need to step-over. Remove from queue. */
+ if (tp->step_over_next != NULL)
+ thread_step_over_chain_remove (tp);
+
+ if (tp->state != THREAD_EXITED)
+ {
+ observer_notify_thread_exit (tp, silent);
+
+ /* Tag it as exited. */
+ tp->state = THREAD_EXITED;
+
+ /* Clear breakpoints, etc. associated with this thread. */
+ clear_thread_inferior_resources (tp);
+ }
+}
+
void
init_thread_list (void)
{
@@ -205,7 +226,10 @@ init_thread_list (void)
for (tp = thread_list; tp; tp = tpnext)
{
tpnext = tp->next;
- delete tp;
+ if (tp->deletable ())
+ delete tp;
+ else
+ set_thread_exited (tp, 1);
}
thread_list = NULL;
@@ -430,25 +454,9 @@ delete_thread_1 (ptid_t ptid, int silent)
if (!tp)
return;
- /* Dead threads don't need to step-over. Remove from queue. */
- if (tp->step_over_next != NULL)
- thread_step_over_chain_remove (tp);
+ set_thread_exited (tp, silent);
- if (tp->state != THREAD_EXITED)
- {
- observer_notify_thread_exit (tp, silent);
-
- /* Tag it as exited. */
- tp->state = THREAD_EXITED;
-
- /* Clear breakpoints, etc. associated with this thread. */
- clear_thread_inferior_resources (tp);
- }
-
- /* If this is the current thread, or there's code out there that
- relies on it existing (refcount > 0) we can't delete yet. */
- if (tp->refcount > 0
- || ptid_equal (tp->ptid, inferior_ptid))
+ if (!tp->deletable ())
{
/* Will be really deleted some other time. */
return;
@@ -1546,7 +1554,7 @@ struct current_thread_cleanup
'current_thread_cleanup_chain' below. */
struct current_thread_cleanup *next;
- ptid_t inferior_ptid;
+ thread_info *thread;
struct frame_id selected_frame_id;
int selected_frame_level;
int was_stopped;
@@ -1561,37 +1569,21 @@ struct current_thread_cleanup
succeeds. */
static struct current_thread_cleanup *current_thread_cleanup_chain;
-/* A thread_ptid_changed observer. Update all currently installed
- current_thread_cleanup cleanups that want to switch back to
- OLD_PTID to switch back to NEW_PTID instead. */
-
-static void
-restore_current_thread_ptid_changed (ptid_t old_ptid, ptid_t new_ptid)
-{
- struct current_thread_cleanup *it;
-
- for (it = current_thread_cleanup_chain; it != NULL; it = it->next)
- {
- if (ptid_equal (it->inferior_ptid, old_ptid))
- it->inferior_ptid = new_ptid;
- }
-}
-
static void
do_restore_current_thread_cleanup (void *arg)
{
- struct thread_info *tp;
struct current_thread_cleanup *old = (struct current_thread_cleanup *) arg;
- tp = find_thread_ptid (old->inferior_ptid);
-
- /* If the previously selected thread belonged to a process that has
- in the mean time been deleted (due to normal exit, detach, etc.),
- then don't revert back to it, but instead simply drop back to no
- thread selected. */
- if (tp
- && find_inferior_ptid (tp->ptid) != NULL)
- restore_current_thread (old->inferior_ptid);
+ /* If an entry of thread_info was previously selected, it won't be
+ deleted because we've increased its refcount. The thread represented
+ by this thread_info entry may have already exited (due to normal exit,
+ detach, etc), so the thread_info.state is THREAD_EXITED. */
+ if (old->thread != NULL
+ /* If the previously selected thread belonged to a process that has
+ in the mean time exited (or killed, detached, etc.), then don't revert
+ back to it, but instead simply drop back to no thread selected. */
+ && find_inferior_ptid (old->thread->ptid) != NULL)
+ restore_current_thread (old->thread->ptid);
else
{
restore_current_thread (null_ptid);
@@ -1619,9 +1611,9 @@ restore_current_thread_cleanup_dtor (void *arg)
current_thread_cleanup_chain = current_thread_cleanup_chain->next;
- tp = find_thread_ptid (old->inferior_ptid);
- if (tp)
- tp->refcount--;
+ if (old->thread != NULL)
+ old->thread->decref ();
+
inf = find_inferior_id (old->inf_id);
if (inf != NULL)
inf->removable = old->was_removable;
@@ -1638,7 +1630,7 @@ set_thread_refcount (void *data)
= (struct thread_array_cleanup *) data;
for (k = 0; k != ta_cleanup->count; k++)
- ta_cleanup->tp_array[k]->refcount--;
+ ta_cleanup->tp_array[k]->decref ();
}
struct cleanup *
@@ -1646,7 +1638,7 @@ make_cleanup_restore_current_thread (void)
{
struct current_thread_cleanup *old = XNEW (struct current_thread_cleanup);
- old->inferior_ptid = inferior_ptid;
+ old->thread = NULL;
old->inf_id = current_inferior ()->num;
old->was_removable = current_inferior ()->removable;
@@ -1679,7 +1671,8 @@ make_cleanup_restore_current_thread (void)
struct thread_info *tp = find_thread_ptid (inferior_ptid);
if (tp)
- tp->refcount++;
+ tp->incref ();
+ old->thread = tp;
}
current_inferior ()->removable = 0;
@@ -1796,7 +1789,7 @@ thread_apply_all_command (char *cmd, int from_tty)
ALL_NON_EXITED_THREADS (tp)
{
tp_array[i] = tp;
- tp->refcount++;
+ tp->incref ();
i++;
}
/* Because we skipped exited threads, we may end up with fewer
@@ -2286,6 +2279,4 @@ Show printing of thread events (such as thread start and exit)."), NULL,
create_internalvar_type_lazy ("_thread", &thread_funcs, NULL);
create_internalvar_type_lazy ("_gthread", &gthread_funcs, NULL);
-
- observer_attach_thread_ptid_changed (restore_current_thread_ptid_changed);
}