Commit f982f91516fa4cfd9d20518833cd04ad714585be
Committed by
Linus Torvalds
1 parent
97c24d1d45
Exists in
master
and in
20 other branches
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>
Showing 1 changed file with 4 additions and 3 deletions Side-by-side Diff
mm/vmalloc.c
... | ... | @@ -725,9 +725,10 @@ |
725 | 725 | #define VMAP_BBMAP_BITS_MIN (VMAP_MAX_ALLOC*2) |
726 | 726 | #define VMAP_MIN(x, y) ((x) < (y) ? (x) : (y)) /* can't use min() */ |
727 | 727 | #define VMAP_MAX(x, y) ((x) > (y) ? (x) : (y)) /* can't use max() */ |
728 | -#define VMAP_BBMAP_BITS VMAP_MIN(VMAP_BBMAP_BITS_MAX, \ | |
729 | - VMAP_MAX(VMAP_BBMAP_BITS_MIN, \ | |
730 | - VMALLOC_PAGES / NR_CPUS / 16)) | |
728 | +#define VMAP_BBMAP_BITS \ | |
729 | + VMAP_MIN(VMAP_BBMAP_BITS_MAX, \ | |
730 | + VMAP_MAX(VMAP_BBMAP_BITS_MIN, \ | |
731 | + VMALLOC_PAGES / roundup_pow_of_two(NR_CPUS) / 16)) | |
731 | 732 | |
732 | 733 | #define VMAP_BLOCK_SIZE (VMAP_BBMAP_BITS * PAGE_SIZE) |
733 | 734 |