diff options
| author | Oleg Nesterov <oleg@redhat.com> | 2015-11-06 16:32:31 -0800 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2015-11-06 17:50:42 -0800 |
| commit | 5fa534c987784c4811757a34c425aff3ce3b5037 (patch) | |
| tree | 09aa19be1afc7e10913f29758055c2056d5d3695 | |
| parent | 9317bb9696566e6759203ffcaa80481b725785b3 (diff) | |
| download | linux-5fa534c987784c4811757a34c425aff3ce3b5037.tar.bz2 | |
coredump: ensure all coredumping tasks have SIGNAL_GROUP_COREDUMP
task_will_free_mem() is wrong in many ways, and in particular the
SIGNAL_GROUP_COREDUMP check is not reliable: a task can participate in the
coredumping without SIGNAL_GROUP_COREDUMP bit set.
change zap_threads() paths to always set SIGNAL_GROUP_COREDUMP even if
other CLONE_VM processes can't react to SIGKILL. Fortunately, at least
oom-kill case if fine; it kills all tasks sharing the same mm, so it
should also kill the process which actually dumps the core.
The change in prepare_signal() is not strictly necessary, it just ensures
that the patch does not bring another subtle behavioural change. But it
reminds us that this SIGNAL_GROUP_EXIT/COREDUMP case needs more changes.
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Kyle Walker <kwalker@redhat.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Stanislav Kozina <skozina@redhat.com>
Cc: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
| -rw-r--r-- | fs/coredump.c | 12 | ||||
| -rw-r--r-- | kernel/signal.c | 2 |
2 files changed, 7 insertions, 7 deletions
diff --git a/fs/coredump.c b/fs/coredump.c index a8f75640ac86..c66bb0572265 100644 --- a/fs/coredump.c +++ b/fs/coredump.c @@ -280,11 +280,13 @@ out: return ispipe; } -static int zap_process(struct task_struct *start, int exit_code) +static int zap_process(struct task_struct *start, int exit_code, int flags) { struct task_struct *t; int nr = 0; + /* ignore all signals except SIGKILL, see prepare_signal() */ + start->signal->flags = SIGNAL_GROUP_COREDUMP | flags; start->signal->group_exit_code = exit_code; start->signal->group_stop_count = 0; @@ -311,10 +313,8 @@ static int zap_threads(struct task_struct *tsk, struct mm_struct *mm, spin_lock_irq(&tsk->sighand->siglock); if (!signal_group_exit(tsk->signal)) { mm->core_state = core_state; - nr = zap_process(tsk, exit_code); tsk->signal->group_exit_task = tsk; - /* ignore all signals except SIGKILL, see prepare_signal() */ - tsk->signal->flags = SIGNAL_GROUP_COREDUMP; + nr = zap_process(tsk, exit_code, 0); clear_tsk_thread_flag(tsk, TIF_SIGPENDING); } spin_unlock_irq(&tsk->sighand->siglock); @@ -365,8 +365,8 @@ static int zap_threads(struct task_struct *tsk, struct mm_struct *mm, if (p->mm) { if (unlikely(p->mm == mm)) { lock_task_sighand(p, &flags); - nr += zap_process(p, exit_code); - p->signal->flags = SIGNAL_GROUP_EXIT; + nr += zap_process(p, exit_code, + SIGNAL_GROUP_EXIT); unlock_task_sighand(p, &flags); } break; diff --git a/kernel/signal.c b/kernel/signal.c index f2cbd4ed5cd4..c0b01fe24bbd 100644 --- a/kernel/signal.c +++ b/kernel/signal.c @@ -788,7 +788,7 @@ static bool prepare_signal(int sig, struct task_struct *p, bool force) sigset_t flush; if (signal->flags & (SIGNAL_GROUP_EXIT | SIGNAL_GROUP_COREDUMP)) { - if (signal->flags & SIGNAL_GROUP_COREDUMP) + if (!(signal->flags & SIGNAL_GROUP_EXIT)) return sig == SIGKILL; /* * The process is in the middle of dying, nothing to do. |