signal: Remove the bogus sigkill_pending in ptrace_stop

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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: 3d749b9e67 ("ptrace: simplify ptrace_stop()->sigkill_pending() path")
Fixes: 1a669c2f16 ("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>

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This commit is contained in:

Eric W. Biederman 2021-09-01 13:21:34 -05:00

parent 6880fa6c56

commit 7d613f9f72

1 changed files with 4 additions and 14 deletions

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kernel/signal.c

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