From: José Bollo <jose.bollo@open.eurogiciel.org>
Date: Thu, 3 Apr 2014 11:48:41 +0000 (+0200)
Subject: SMACK: Fix handling value==NULL in post setxattr
X-Git-Tag: omap-for-v3.16/fixes-against-rc1~70^2~5^2~5
X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=9598f4c9e7069aee8639be1e04e8af26b5a77fa2;p=pandora-kernel.git

SMACK: Fix handling value==NULL in post setxattr

The function `smack_inode_post_setxattr` is called each
time that a setxattr is done, for any value of name.
The kernel allow to put value==NULL when size==0
to set an empty attribute value. The systematic
call to smk_import_entry was causing the dereference
of a NULL pointer hence a KERNEL PANIC!

The problem can be produced easily by issuing the
command `setfattr -n user.data file` under bash prompt
when SMACK is active.

Moving the call to smk_import_entry as proposed by this
patch is correcting the behaviour because the function
smack_inode_post_setxattr is called for the SMACK's
attributes only if the function smack_inode_setxattr validated
the value and its size (what will not be the case when size==0).

It also has a benefical effect to not fill the smack hash
with garbage values coming from any extended attribute
write.

Change-Id: Iaf0039c2be9bccb6cee11c24a3b44d209101fe47
Signed-off-by: José Bollo <jose.bollo@open.eurogiciel.org>
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