Commit 4617f564 authored by Adrian Salido's avatar Adrian Salido Committed by Mike Snitzer

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: default avatarAdrian Salido <salidoa@google.com>
Reviewed-by: default avatarAlasdair G Kergon <agk@redhat.com>
Signed-off-by: default avatarMike Snitzer <snitzer@redhat.com>
parent 84ff1bcc
......@@ -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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