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restorer: Block signals early

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Otherwise threads can handle them before calling sigreturn with wrong (not
belonging to crtools, but to the target task) handers:

__export_restore_task				| __export_restore_thread

restore_finish_stage(CR_STATE_RESTORE);		| restore_finish_stage(CR_STATE_RESTORE);
sys_sigaction(SIGCHLD, &args->sigchld_act, ...) |
restore_signals()				|
	ksigfillset(&to_block);			|
	sys_rt_sigqueueinfo(sys_getpid(), ...); |
						| execute signal handler() <------ BUG !!!
						| restore_signals()
						|	ksigfillset(&to_block);

Signed-off-by: Andrey Vagin <avagin@openvz.org>
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>
This commit is contained in:
Andrey Vagin
2013-09-20 20:04:46 +04:00
committed by Pavel Emelyanov
parent c721a2751f
commit 5d18eca3d5
1 changed files with 17 additions and 8 deletions
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25
pie/restorer.c
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@@ -211,14 +211,6 @@ static void restore_rlims(struct task_restore_core_args *ta)
static int restore_signals(siginfo_t *ptr, int nr, bool group)
{
int ret, i;
k_rtsigset_t to_block;
ksigfillset(&to_block);
ret = sys_sigprocmask(SIG_SETMASK, &to_block, NULL, sizeof(k_rtsigset_t));
if (ret) {
pr_err("Unable to block signals %d", ret);
return -1;
}
for (i = 0; i < nr; i++) {
siginfo_t *info = ptr + i;
@@ -272,6 +264,7 @@ static int restore_thread_common(struct rt_sigframe *sigframe,
long __export_restore_thread(struct thread_restore_args *args)
{
struct rt_sigframe *rt_sigframe;
k_rtsigset_t to_block;
unsigned long new_sp;
int my_pid = sys_gettid();
int ret;
@@ -281,6 +274,14 @@ long __export_restore_thread(struct thread_restore_args *args)
goto core_restore_end;
}
/* All signals must be handled by thread leader */
ksigfillset(&to_block);
ret = sys_sigprocmask(SIG_SETMASK, &to_block, NULL, sizeof(k_rtsigset_t));
if (ret) {
pr_err("Unable to block signals %d", ret);
goto core_restore_end;
}
rt_sigframe = (void *)args->mem_zone.rt_sigframe;
if (restore_thread_common(rt_sigframe, args))
@@ -527,6 +528,7 @@ long __export_restore_task(struct task_restore_core_args *args)
struct rt_sigframe *rt_sigframe;
unsigned long new_sp;
k_rtsigset_t to_block;
pid_t my_pid = sys_getpid();
rt_sigaction_t act;
@@ -855,6 +857,13 @@ long __export_restore_task(struct task_restore_core_args *args)
futex_wait_while_gt(&zombies_inprogress, 0);
ksigfillset(&to_block);
ret = sys_sigprocmask(SIG_SETMASK, &to_block, NULL, sizeof(k_rtsigset_t));
if (ret) {
pr_err("Unable to block signals %ld", ret);
goto core_restore_end;
}
sys_sigaction(SIGCHLD, &args->sigchld_act, NULL, sizeof(k_rtsigset_t));
ret = restore_signals(args->siginfo, args->siginfo_nr, true);