mm: fix wrong vmap address calculations with odd NR_CPUS values
authorClemens Ladisch <clemens@ladisch.de>
Tue, 21 Jun 2011 20:09:50 +0000 (22:09 +0200)
committerLinus Torvalds <torvalds@linux-foundation.org>
Sun, 14 Aug 2011 19:32:52 +0000 (12:32 -0700)
commitf982f91516fa4cfd9d20518833cd04ad714585be
tree15c7992ad6e54fbda868a026afd5ecf98f9b1bca
parent97c24d1d455df17ca3ef281d1a290988f4686643
mm: fix wrong vmap address calculations with odd NR_CPUS values

Commit db64fe02258f ("mm: rewrite vmap layer") introduced code that does
address calculations under the assumption that VMAP_BLOCK_SIZE is a
power of two.  However, this might not be true if CONFIG_NR_CPUS is not
set to a power of two.

Wrong vmap_block index/offset values could lead to memory corruption.
However, this has never been observed in practice (or never been
diagnosed correctly); what caught this was the BUG_ON in vb_alloc() that
checks for inconsistent vmap_block indices.

To fix this, ensure that VMAP_BLOCK_SIZE always is a power of two.

BugLink: https://bugzilla.kernel.org/show_bug.cgi?id=31572
Reported-by: Pavel Kysilka <goldenfish@linuxsoft.cz>
Reported-by: Matias A. Fonzo <selk@dragora.org>
Signed-off-by: Clemens Ladisch <clemens@ladisch.de>
Signed-off-by: Stefan Richter <stefanr@s5r6.in-berlin.de>
Cc: Nick Piggin <npiggin@suse.de>
Cc: Jeremy Fitzhardinge <jeremy@goop.org>
Cc: Krzysztof Helt <krzysztof.h1@poczta.fm>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: 2.6.28+ <stable@kernel.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
mm/vmalloc.c