From: Eric Sandeen <sandeen@redhat.com>
Date: Fri, 28 Nov 2014 03:03:55 +0000 (+1100)
Subject: xfs: catch invalid negative blknos in _xfs_buf_find()
X-Git-Tag: omap-for-v3.20/drop-legacy-3517~112^2~3^2
X-Git-Url: https://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=db52d09ecbf85c54e263a9d1ebfb615a9b2b3ba6;p=pandora-kernel.git

xfs: catch invalid negative blknos in _xfs_buf_find()

Here blkno is a daddr_t, which is a __s64; it's possible to hold
a value which is negative, and thus pass the (blkno >= eofs)
test.  Then we try to do a xfs_perag_get() for a ridiculous
agno via xfs_daddr_to_agno(), and bad things happen when that
fails, and returns a null pag which is dereferenced shortly
thereafter.

Found via a user-supplied fuzzed image...

Signed-off-by: Eric Sandeen <sandeen@redhat.com>
Reviewed-by: Mark Tinguely <tinguely@sgi.com>
Signed-off-by: Dave Chinner <david@fromorbit.com>
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