The patch titled
ptrace_stop: fix racy nonstop_code setting
has been removed from the -mm tree. Its filename was
ptrace_stop-fix-racy-nonstop_code-setting.patch
This patch was dropped because it was merged into mainline or a subsystem tree
The current -mm tree may be found at http://userweb.kernel.org/~akpm/mmotm/
------------------------------------------------------
Subject: ptrace_stop: fix racy nonstop_code setting
From: Oleg Nesterov <oleg@xxxxxxxxxx>
If the tracer is gone and we are not going to stop, ptrace_stop() sets
->exit_code = nostop_code. However, the tracer could actually clear the
exit code before detaching. In that case get_signal_to_deliver() "resends"
the signal which was cancelled by the debugger. For example, it is
possible that a quick PTRACE_ATTACH + PTRACE_DETACH can leave the tracee in
STOPPED state.
Change the behaviour of ptrace_stop(). If the caller is ptrace notify(),
we should always clear ->exit_code. If the caller is
get_signal_to_deliver(), we should not touch it at all. To do so, change
the nonstop_code parameter to "bool clear_code" and change the callers
accordingly.
Signed-off-by: Oleg Nesterov <oleg@xxxxxxxxxx>
Acked-by: Roland McGrath <roland@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
kernel/signal.c | 13 +++++++------
1 file changed, 7 insertions(+), 6 deletions(-)
diff -puN kernel/signal.c~ptrace_stop-fix-racy-nonstop_code-setting kernel/signal.c
--- a/kernel/signal.c~ptrace_stop-fix-racy-nonstop_code-setting
+++ a/kernel/signal.c
@@ -1591,10 +1591,10 @@ static int sigkill_pending(struct task_s
* That makes it a way to test a stopped process for
* being ptrace-stopped vs being job-control-stopped.
*
- * If we actually decide not to stop at all because the tracer is gone,
- * we leave nostop_code in current->exit_code.
+ * If we actually decide not to stop at all because the tracer
+ * is gone, we keep current->exit_code unless clear_code.
*/
-static void ptrace_stop(int exit_code, int nostop_code, siginfo_t *info)
+static void ptrace_stop(int exit_code, int clear_code, siginfo_t *info)
{
int killed = 0;
@@ -1641,7 +1641,8 @@ static void ptrace_stop(int exit_code, i
* Don't drop the lock yet, another tracer may come.
*/
__set_current_state(TASK_RUNNING);
- current->exit_code = nostop_code;
+ if (clear_code)
+ current->exit_code = 0;
read_unlock(&tasklist_lock);
}
@@ -1675,7 +1676,7 @@ void ptrace_notify(int exit_code)
/* Let the debugger run. */
spin_lock_irq(¤t->sighand->siglock);
- ptrace_stop(exit_code, 0, &info);
+ ptrace_stop(exit_code, 1, &info);
spin_unlock_irq(¤t->sighand->siglock);
}
@@ -1782,7 +1783,7 @@ relock:
ptrace_signal_deliver(regs, cookie);
/* Let the debugger run. */
- ptrace_stop(signr, signr, info);
+ ptrace_stop(signr, 0, info);
/* We're back. Did the debugger cancel the sig? */
signr = current->exit_code;
_
Patches currently in -mm which might be from oleg@xxxxxxxxxx are
origin.patch
revert-proc-fix-the-threaded-proc-self.patch
procfs-task-exe-symlink.patch
procfs-task-exe-symlink-fix.patch
-
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