mm: fix wrong vmap address calculations with odd NR_CPUS values
Subsystems (2)
PATCH 1/1 mm: fix wrong vmap address calculations with odd NR_CPUS values
Date: Tue, 21 Jun 2011 22:09:50 +0200
From: Clemens Ladisch <[email protected]>
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.
---
This fixes instant and fully repeatable crashes if NR_CPUS is not a power of two and vm_map_ram() or something like that is executed, for example firewire-ohci probe in its 2.6.38+ incarnation.
mm/vmalloc.c | 7 ++++--- 1 files changed, 4 insertions(+), 3 deletions(-)
mm/vmalloc.c +4 -3
@@ -732,9 +732,10 @@ static void free_unmap_vmap_area_addr(unsigned long addr)#define VMAP_BBMAP_BITS_MIN (VMAP_MAX_ALLOC*2)#define VMAP_MIN (x, y) ((x) < (y) ? (x) : (y))/* can't use min() */ #define VMAP_MAX (x, y) ((x) > (y) ? (x) : (y))/* can't use max() */ -#define VMAP_BBMAP_BITS VMAP_MIN(VMAP_BBMAP_BITS_MAX, \ - VMAP_MAX(VMAP_BBMAP_BITS_MIN, \ - VMALLOC_PAGES / NR_CPUS / 16)) +#define VMAP_BBMAP_BITS \ + VMAP_MIN(VMAP_BBMAP_BITS_MAX, \ + VMAP_MAX(VMAP_BBMAP_BITS_MIN, \ + VMALLOC_PAGES / roundup_pow_of_two(NR_CPUS) / 16))#define VMAP_BLOCK_SIZE (VMAP_BBMAP_BITS * PAGE_SIZE)
Signature · 14 lines
1.7.3.2 -- Stefan Richter -=====-==-== =--- -===- http://arcgraph.de/sr/ -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to [email protected]. For more info on Linux MM, see: http://www.linux-mm.org/ . Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/ Don't email: <a href=mailto:"[email protected]"> [email protected] </a>
PATCH 1/1 mm: fix wrong vmap address calculations with odd NR_CPUS values
From: Clemens Ladisch <[email protected]>
Date: Tue, 21 Jun 2011 22:09:50 +0200
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.
---
Resend with corrected Cc list; sorry.
This fixes instant and fully repeatable crashes if NR_CPUS is not a power of two and vm_map_ram() or something like that is executed, for example firewire-ohci probe in its 2.6.38+ incarnation.
mm/vmalloc.c | 7 ++++--- 1 files changed, 4 insertions(+), 3 deletions(-)
mm/vmalloc.c +4 -3
@@ -732,9 +732,10 @@ static void free_unmap_vmap_area_addr(unsigned long addr)#define VMAP_BBMAP_BITS_MIN (VMAP_MAX_ALLOC*2)#define VMAP_MIN (x, y) ((x) < (y) ? (x) : (y))/* can't use min() */ #define VMAP_MAX (x, y) ((x) > (y) ? (x) : (y))/* can't use max() */ -#define VMAP_BBMAP_BITS VMAP_MIN(VMAP_BBMAP_BITS_MAX, \ - VMAP_MAX(VMAP_BBMAP_BITS_MIN, \ - VMALLOC_PAGES / NR_CPUS / 16)) +#define VMAP_BBMAP_BITS \ + VMAP_MIN(VMAP_BBMAP_BITS_MAX, \ + VMAP_MAX(VMAP_BBMAP_BITS_MIN, \ + VMALLOC_PAGES / roundup_pow_of_two(NR_CPUS) / 16))#define VMAP_BLOCK_SIZE (VMAP_BBMAP_BITS * PAGE_SIZE)
Signature · 8 lines
1.7.3.2 -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to [email protected]. For more info on Linux MM, see: http://www.linux-mm.org/ . Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/ Don't email: <a href=mailto:"[email protected]"> [email protected] </a>