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authorEric W. Biederman <ebiederm@xmission.com>2021-09-01 21:21:34 +0300
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2021-11-18 21:16:01 +0300
commit4a2aba3252e85784c266c77050771d3808c6f680 (patch)
tree20b646a9be7c64d43468e954c923825dbc3ff94d /kernel
parentb6a38dd58e4d44cc13fb80b44be8ad402c155e44 (diff)
downloadlinux-4a2aba3252e85784c266c77050771d3808c6f680.tar.xz
signal: Remove the bogus sigkill_pending in ptrace_stop
commit 7d613f9f72ec8f90ddefcae038fdae5adb8404b3 upstream. The existence of sigkill_pending is a little silly as it is functionally a duplicate of fatal_signal_pending that is used in exactly one place. Checking for pending fatal signals and returning early in ptrace_stop is actively harmful. It casues the ptrace_stop called by ptrace_signal to return early before setting current->exit_code. Later when ptrace_signal reads the signal number from current->exit_code is undefined, making it unpredictable what will happen. Instead rely on the fact that schedule will not sleep if there is a pending signal that can awaken a task. Removing the explict sigkill_pending test fixes fixes ptrace_signal when ptrace_stop does not stop because current->exit_code is always set to to signr. Cc: stable@vger.kernel.org Fixes: 3d749b9e676b ("ptrace: simplify ptrace_stop()->sigkill_pending() path") Fixes: 1a669c2f16d4 ("Add arch_ptrace_stop") Link: https://lkml.kernel.org/r/87pmsyx29t.fsf@disp2133 Reviewed-by: Kees Cook <keescook@chromium.org> Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'kernel')
-rw-r--r--kernel/signal.c18
1 files changed, 4 insertions, 14 deletions
diff --git a/kernel/signal.c b/kernel/signal.c
index 487bf4f5dadf..cdf314be1373 100644
--- a/kernel/signal.c
+++ b/kernel/signal.c
@@ -2169,15 +2169,6 @@ static inline bool may_ptrace_stop(void)
return true;
}
-/*
- * Return non-zero if there is a SIGKILL that should be waking us up.
- * Called with the siglock held.
- */
-static bool sigkill_pending(struct task_struct *tsk)
-{
- return sigismember(&tsk->pending.signal, SIGKILL) ||
- sigismember(&tsk->signal->shared_pending.signal, SIGKILL);
-}
/*
* This must be called with current->sighand->siglock held.
@@ -2204,17 +2195,16 @@ static void ptrace_stop(int exit_code, int why, int clear_code, kernel_siginfo_t
* calling arch_ptrace_stop, so we must release it now.
* To preserve proper semantics, we must do this before
* any signal bookkeeping like checking group_stop_count.
- * Meanwhile, a SIGKILL could come in before we retake the
- * siglock. That must prevent us from sleeping in TASK_TRACED.
- * So after regaining the lock, we must check for SIGKILL.
*/
spin_unlock_irq(&current->sighand->siglock);
arch_ptrace_stop(exit_code, info);
spin_lock_irq(&current->sighand->siglock);
- if (sigkill_pending(current))
- return;
}
+ /*
+ * schedule() will not sleep if there is a pending signal that
+ * can awaken the task.
+ */
set_special_state(TASK_TRACED);
/*