From: Eric W. Biederman Date: Wed, 15 May 2019 17:29:52 +0000 (-0500) Subject: signal/pid_namespace: Fix reboot_pid_ns to use send_sig not force_sig X-Git-Tag: v4.14.135~272 X-Git-Url: https://www.infradead.org/git/?a=commitdiff_plain;h=b49b8338c4216b79f72f626455802ce23d57a654;p=users%2Fdwmw2%2Flinux.git signal/pid_namespace: Fix reboot_pid_ns to use send_sig not force_sig [ Upstream commit f9070dc94542093fd516ae4ccea17ef46a4362c5 ] The locking in force_sig_info is not prepared to deal with a task that exits or execs (as sighand may change). The is not a locking problem in force_sig as force_sig is only built to handle synchronous exceptions. Further the function force_sig_info changes the signal state if the signal is ignored, or blocked or if SIGNAL_UNKILLABLE will prevent the delivery of the signal. The signal SIGKILL can not be ignored and can not be blocked and SIGNAL_UNKILLABLE won't prevent it from being delivered. So using force_sig rather than send_sig for SIGKILL is confusing and pointless. Because it won't impact the sending of the signal and and because using force_sig is wrong, replace force_sig with send_sig. Cc: Daniel Lezcano Cc: Serge Hallyn Cc: Oleg Nesterov Fixes: cf3f89214ef6 ("pidns: add reboot_pid_ns() to handle the reboot syscall") Signed-off-by: "Eric W. Biederman" Signed-off-by: Sasha Levin --- diff --git a/kernel/pid_namespace.c b/kernel/pid_namespace.c index 4918314893bc6..22091c88b3bb7 100644 --- a/kernel/pid_namespace.c +++ b/kernel/pid_namespace.c @@ -351,7 +351,7 @@ int reboot_pid_ns(struct pid_namespace *pid_ns, int cmd) } read_lock(&tasklist_lock); - force_sig(SIGKILL, pid_ns->child_reaper); + send_sig(SIGKILL, pid_ns->child_reaper, 1); read_unlock(&tasklist_lock); do_exit(0);