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| author | Eric W. Biederman <ebiederm@xmission.com> | 2021-09-01 13:21:34 -0500 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2021-11-17 09:48:24 +0100 |
| commit | ec5ef8d4d7954d570d1a018677cb4cb0ffbf00cf (patch) | |
| tree | ea45294a40e58da80478b84163e63d786d56eecd /kernel | |
| parent | 28c70d50363d8dd5f476b0f31b748e335983d413 (diff) | |
| download | linux-stable-ec5ef8d4d7954d570d1a018677cb4cb0ffbf00cf.tar.gz linux-stable-ec5ef8d4d7954d570d1a018677cb4cb0ffbf00cf.tar.bz2 linux-stable-ec5ef8d4d7954d570d1a018677cb4cb0ffbf00cf.zip | |
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.c | 18 |
1 files changed, 4 insertions, 14 deletions
diff --git a/kernel/signal.c b/kernel/signal.c index 8c97fc72d78b..3f61367fd168 100644 --- a/kernel/signal.c +++ b/kernel/signal.c @@ -2101,15 +2101,6 @@ 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. @@ -2136,17 +2127,16 @@ 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(¤t->sighand->siglock); arch_ptrace_stop(exit_code, info); spin_lock_irq(¤t->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); /* |