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| author | Eric W. Biederman <ebiederm@xmission.com> | 2022-04-29 15:43:34 +0200 |
|---|---|---|
| committer | Eric W. Biederman <ebiederm@xmission.com> | 2022-05-11 21:35:32 +0200 |
| commit | 2500ad1c7fa42ad734677853961a3a8bec0772c5 (patch) | |
| tree | e94af9b15cf725771c652439f12c2c9607663c38 /kernel/signal.c | |
| parent | ptrace: Admit ptrace_stop can generate spuriuos SIGTRAPs (diff) | |
| download | linux-2500ad1c7fa42ad734677853961a3a8bec0772c5.tar.xz linux-2500ad1c7fa42ad734677853961a3a8bec0772c5.zip | |
ptrace: Don't change __state
Stop playing with tsk->__state to remove TASK_WAKEKILL while a ptrace
command is executing.
Instead remove TASK_WAKEKILL from the definition of TASK_TRACED, and
implement a new jobctl flag TASK_PTRACE_FROZEN. This new flag is set
in jobctl_freeze_task and cleared when ptrace_stop is awoken or in
jobctl_unfreeze_task (when ptrace_stop remains asleep).
In signal_wake_up add __TASK_TRACED to state along with TASK_WAKEKILL
when the wake up is for a fatal signal. Skip adding __TASK_TRACED
when TASK_PTRACE_FROZEN is not set. This has the same effect as
changing TASK_TRACED to __TASK_TRACED as all of the wake_ups that use
TASK_KILLABLE go through signal_wake_up.
Handle a ptrace_stop being called with a pending fatal signal.
Previously it would have been handled by schedule simply failing to
sleep. As TASK_WAKEKILL is no longer part of TASK_TRACED schedule
will sleep with a fatal_signal_pending. The code in signal_wake_up
guarantees that the code will be awaked by any fatal signal that
codes after TASK_TRACED is set.
Previously the __state value of __TASK_TRACED was changed to
TASK_RUNNING when woken up or back to TASK_TRACED when the code was
left in ptrace_stop. Now when woken up ptrace_stop now clears
JOBCTL_PTRACE_FROZEN and when left sleeping ptrace_unfreezed_traced
clears JOBCTL_PTRACE_FROZEN.
Tested-by: Kees Cook <keescook@chromium.org>
Reviewed-by: Oleg Nesterov <oleg@redhat.com>
Link: https://lkml.kernel.org/r/20220505182645.497868-10-ebiederm@xmission.com
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
Diffstat (limited to 'kernel/signal.c')
| -rw-r--r-- | kernel/signal.c | 14 |
1 files changed, 6 insertions, 8 deletions
diff --git a/kernel/signal.c b/kernel/signal.c index d2d0c753156c..a58b68a2d3c6 100644 --- a/kernel/signal.c +++ b/kernel/signal.c @@ -2209,14 +2209,12 @@ static int ptrace_stop(int exit_code, int why, unsigned long message, } /* - * schedule() will not sleep if there is a pending signal that - * can awaken the task. - * - * After this point ptrace_signal_wake_up will clear TASK_TRACED - * if ptrace_unlink happens. Handle previous ptrace_unlinks - * here to prevent ptrace_stop sleeping in schedule. + * After this point ptrace_signal_wake_up or signal_wake_up + * will clear TASK_TRACED if ptrace_unlink happens or a fatal + * signal comes in. Handle previous ptrace_unlinks and fatal + * signals here to prevent ptrace_stop sleeping in schedule. */ - if (!current->ptrace) + if (!current->ptrace || __fatal_signal_pending(current)) return exit_code; set_special_state(TASK_TRACED); @@ -2305,7 +2303,7 @@ static int ptrace_stop(int exit_code, int why, unsigned long message, current->exit_code = 0; /* LISTENING can be set only during STOP traps, clear it */ - current->jobctl &= ~JOBCTL_LISTENING; + current->jobctl &= ~(JOBCTL_LISTENING | JOBCTL_PTRACE_FROZEN); /* * Queued signals ignored us while we were stopped for tracing. |