Commit aebe2f15 authored by Adrian Salido's avatar Adrian Salido Committed by Ben Hutchings

dm ioctl: prevent stack leak in dm ioctl call

commit 4617f564 upstream.

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.
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>
Signed-off-by: default avatarBen Hutchings <ben@decadent.org.uk>
parent 356fab89
......@@ -1839,7 +1839,7 @@ 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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