Commit 4617f564 authored Apr 27, 2017 by Adrian Salido Committed by Mike Snitzer Apr 27, 2017

dm ioctl: prevent stack leak in dm ioctl call



When calling a dm ioctl that doesn't process any data
(IOCTL_FLAGS_NO_PARAMS), the contents of the data field in struct
dm_ioctl are left initialized.  Current code is incorrectly extending
the size of data copied back to user, causing the contents of kernel
stack to be leaked to user.  Fix by only copying contents before data
and allow the functions processing the ioctl to override.

Cc: stable@vger.kernel.org
Signed-off-by: Adrian Salido <salidoa@google.com>
Reviewed-by: Alasdair G Kergon <agk@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>

parent 84ff1bcc

drivers/md/dm-ioctl.c

+1 −1

Original line number	Diff line number	Diff line
		@@ -1840,7 +1840,7 @@ static int ctl_ioctl(uint command, struct dm_ioctl __user *user)
		if (r)
		goto out;

		param->data_size = sizeof(*param);
		param->data_size = offsetof(struct dm_ioctl, data);
		r = fn(param, input_param_size);

		if (unlikely(param->flags & DM_BUFFER_FULL_FLAG) &&

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