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pstore/ram: Do not treat empty buffers as valid
authorJoel Fernandes (Google) <joel@joelfernandes.org>
Sat, 3 Nov 2018 23:38:18 +0000 (16:38 -0700)
committerKees Cook <keescook@chromium.org>
Tue, 4 Dec 2018 00:52:35 +0000 (16:52 -0800)
commit30696378f68a9e3dad6bfe55938b112e72af00c2
tree71c33eafa0fa9dd7a969b868fd9ae3cdda86e10a
parentb05c950698fe1edb1d67a00ecd034754e7dad8bb
pstore/ram: Do not treat empty buffers as valid

The ramoops backend currently calls persistent_ram_save_old() even
if a buffer is empty. While this appears to work, it is does not seem
like the right thing to do and could lead to future bugs so lets avoid
that. It also prevents misleading prints in the logs which claim the
buffer is valid.

I got something like:

found existing buffer, size 0, start 0

When I was expecting:

no valid data in buffer (sig = ...)

This bails out early (and reports with pr_debug()), since it's an
acceptable state.

Signed-off-by: Joel Fernandes (Google) <joel@joelfernandes.org>
Co-developed-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Kees Cook <keescook@chromium.org>
fs/pstore/ram_core.c