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dm ioctl: prevent stack leak in dm ioctl call

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commit 4617f564c06117c7d1b611be49521a4430042287 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: Adrian Salido <salidoa@google.com>
Reviewed-by: Alasdair G Kergon <agk@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Adrian Salido 2017-04-27 10:32:55 -07:00 committed by Greg Kroah-Hartman
parent a351e9b9fc
commit 40a1937317
1 changed files with 1 additions and 1 deletions
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2
drivers/md/dm-ioctl.c
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@ -1848,7 +1848,7 @@ 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) &&