linux-kernel - hfsplus corrupts filesystems >2TB

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Message-Id: <1254883878.4246.191.camel@localhost>
Date:	Wed, 07 Oct 2009 03:51:18 +0100
From:	Ben Hutchings <ben@...adent.org.uk>
To:	linux-kernel@...r.kernel.org
Cc:	Eric Sesterhenn <snakebyte@....de>,
	Roman Zippel <zippel@...ux-m68k.org>
Subject: hfsplus corrupts filesystems >2TB

A Debian bug report <http://bugs.debian.org/550010> alerted me to the
fact that hfsplus is not using enough bits for some sector calculations.

hfsplus_get_block() does:

	u32 ablock, dblock, mask;
...
	map_bh(bh_result, sb, (dblock << HFSPLUS_SB(sb).fs_shift) + HFSPLUS_SB(sb).blockoffset + (iblock & mask));

which results in overflow when the sector number is >2^32.  Now it might
be sufficient to change the last line to:

	map_bh(bh_result, sb, ((sector_t)dblock << HFSPLUS_SB(sb).fs_shift) + HFSPLUS_SB(sb).blockoffset + (iblock & mask));

but there may be many other places where u32 must be changed to
sector_t.

For Debian's stable release, I'm intending to prevent mounting volumes
larger than 2^32 sectors (2TB).  Is anyone interested in fixing this
properly or should I submit the same change for mainline?

Ben.

-- 
Ben Hutchings
To err is human; to really foul things up requires a computer.

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