From: Konstantin Khlebnikov <k.khlebnikov@samsung.com>
Date: Thu, 7 Aug 2014 16:52:43 +0000 (+0400)
Subject: Smack: handle zero-length security labels without panic
X-Git-Tag: fixes-against-v3.18-rc2~106^2~11^2~6
X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=b862e561bad6372872f5bf98d95f4131d265b110;p=pandora-kernel.git

Smack: handle zero-length security labels without panic

Zero-length security labels are invalid but kernel should handle them.

This patch fixes kernel panic after setting zero-length security labels:
# attr -S -s "SMACK64" -V "" file

And after writing zero-length string into smackfs files syslog and onlycp:
# python -c 'import os; os.write(1, "")' > /smack/syslog

The problem is caused by brain-damaged logic in function smk_parse_smack()
which takes pointer to buffer and its length but if length below or equal zero
it thinks that the buffer is zero-terminated. Unfortunately callers of this
function are widely used and proper fix requires serious refactoring.

Signed-off-by: Konstantin Khlebnikov <k.khlebnikov@samsung.com>
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