md: don't use flush_signals in userspace processes (f9c79bc0) · Commits · 戴 / test

The function flush_signals clears all pending signals for the process. It may be used by kernel threads when we need to prepare a kernel thread for responding to signals. However using this function for an userspaces processes is incorrect - clearing signals without the program expecting it can cause misbehavior. The raid1 and raid5 code uses flush_signals in its request routine because it wants to prepare for an interruptible wait. This patch drops flush_signals and uses sigprocmask instead to block all signals (including SIGKILL) around the schedule() call. The signals are not lost, but the schedule() call won't respond to them. Signed-off-by:

Mikulas Patocka <mpatocka@redhat.com> Cc: stable@vger.kernel.org Acked-by:

NeilBrown <neilb@suse.com> Signed-off-by:

Shaohua Li <shli@fb.com>

drivers/md/raid1.c

+4 −1

Original line number	Diff line number	Diff line
		@@ -1334,7 +1334,7 @@ static void raid1_write_request(struct mddev mddev, struct bio bio,
		*/
		DEFINE_WAIT(w);
		for (;;) {
		flush_signals(current);
		sigset_t full, old;
		prepare_to_wait(&conf->wait_barrier,
		&w, TASK_INTERRUPTIBLE);
		if (bio_end_sector(bio) <= mddev->suspend_lo \|\|
		@@ -1344,7 +1344,10 @@ static void raid1_write_request(struct mddev mddev, struct bio bio,
		bio->bi_iter.bi_sector,
		bio_end_sector(bio))))
		break;
		sigfillset(&full);
		sigprocmask(SIG_BLOCK, &full, &old);
		schedule();
		sigprocmask(SIG_SETMASK, &old, NULL);
		}
		finish_wait(&conf->wait_barrier, &w);
		}

drivers/md/raid5.c

+4 −1

Original line number	Diff line number	Diff line
		@@ -5693,12 +5693,15 @@ static bool raid5_make_request(struct mddev mddev, struct bio bi)
		* userspace, we want an interruptible
		* wait.
		*/
		flush_signals(current);
		prepare_to_wait(&conf->wait_for_overlap,
		&w, TASK_INTERRUPTIBLE);
		if (logical_sector >= mddev->suspend_lo &&
		logical_sector < mddev->suspend_hi) {
		sigset_t full, old;
		sigfillset(&full);
		sigprocmask(SIG_BLOCK, &full, &old);
		schedule();
		sigprocmask(SIG_SETMASK, &old, NULL);
		do_prepare = true;
		}
		goto retry;

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