coredump: refuse negative skips

The dump_skip_to() helper calculates a relative skip based on the
absolute positon of the coredump:

	cprm->to_skip = pos - cprm->pos;

That's easy to mess up for callers and one already did. This risk
endless zero PAGE_SIZE loops or overwriting already written coredump
data thereby corrupting the dump.

I don't think skipping backwards has any meaning. So warn and refuse.

Link: https://patch.msgid.link/20260820-work-coredump-sparse-v2-2-ba32dd718c51@kernel.org
Signed-off-by: Christian Brauner (Amutable) <brauner@kernel.org>

0 files changed, 0 insertions, 0 deletions