Messages in this thread Patch in this message | | | Date | Tue, 26 Apr 2011 22:37:11 +0200 | From | Oleg Nesterov <> | Subject | [PATCH 1/1] tile: do_hardwall_trap: do not play with task->sighand |
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1. do_hardwall_trap() checks ->sighand != NULL and then takes ->siglock.
This is unsafe even if the task can't run (I assume it is pinned to the same CPU), its parent can reap the task and set ->sighand = NULL right after this check. Even if the compiler dosn't read ->sighand twice and this memory can't to away __group_send_sig_info() is wrong after that. Use do_send_sig_info().
2. Send SIGILL to the thread, not to the whole process. Unless it has the handler or blocked this kills the whole thread-group as before. IIUC, different threads can be bound to different rect's.
3. Check PF_EXITING instead of ->sighand. A zombie thread can go away but its ->sighand can be !NULL.
Reported-by: Matt Fleming <matt@console-pimps.org> Signed-off-by: Oleg Nesterov <oleg@redhat.com> ---
arch/tile/kernel/hardwall.c | 6 ++---- 1 file changed, 2 insertions(+), 4 deletions(-)
--- sigprocmask/arch/tile/kernel/hardwall.c~1_sighand 2011-04-06 21:33:42.000000000 +0200 +++ sigprocmask/arch/tile/kernel/hardwall.c 2011-04-21 20:56:36.000000000 +0200 @@ -268,12 +268,10 @@ void __kprobes do_hardwall_trap(struct p found_processes = 0; list_for_each_entry(p, &rect->task_head, thread.hardwall_list) { BUG_ON(p->thread.hardwall != rect); - if (p->sighand) { + if (!(p->flags & PF_EXITING)) { found_processes = 1; pr_notice("hardwall: killing %d\n", p->pid); - spin_lock(&p->sighand->siglock); - __group_send_sig_info(info.si_signo, &info, p); - spin_unlock(&p->sighand->siglock); + do_send_sig_info(info.si_signo, &info, p, false); } } if (!found_processes)
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