From b64b6bf4fd8b678a9f8477c11773c38a0a246a6d Mon Sep 17 00:00:00 2001 From: Mikulas Patocka Date: Thu, 2 Apr 2009 19:55:24 +0100 Subject: [PATCH] dm io: make sync_io uninterruptible If someone sends signal to a process performing synchronous dm-io call, the kernel may crash. The function sync_io attempts to exit with -EINTR if it has pending signal, however the structure "io" is allocated on stack, so already submitted io requests end up touching unallocated stack space and corrupting kernel memory. sync_io sets its state to TASK_UNINTERRUPTIBLE, so the signal can't break out of io_schedule() --- however, if the signal was pending before sync_io entered while (1) loop, the corruption of kernel memory will happen. There is no way to cancel in-progress IOs, so the best solution is to ignore signals at this point. Cc: stable@kernel.org Signed-off-by: Mikulas Patocka Signed-off-by: Alasdair G Kergon --- drivers/md/dm-io.c | 5 +---- 1 file changed, 1 insertion(+), 4 deletions(-) diff --git a/drivers/md/dm-io.c b/drivers/md/dm-io.c index 36e2b5e..e73aabd 100644 --- a/drivers/md/dm-io.c +++ b/drivers/md/dm-io.c @@ -370,16 +370,13 @@ static int sync_io(struct dm_io_client *client, unsigned int num_regions, while (1) { set_current_state(TASK_UNINTERRUPTIBLE); - if (!atomic_read(&io.count) || signal_pending(current)) + if (!atomic_read(&io.count)) break; io_schedule(); } set_current_state(TASK_RUNNING); - if (atomic_read(&io.count)) - return -EINTR; - if (error_bits) *error_bits = io.error_bits; -- 2.7.4