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| author | Mitsuo Hayasaka <mitsuo.hayasaka.hu@hitachi.com> | 2011-11-10 13:37:16 +0900 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@suse.de> | 2011-11-26 09:10:36 -0800 |
| commit | f26b4e9506488626dfaacd6733f7e963f4c4ffc2 (patch) | |
| tree | 18685b722ee1e9d51ca8fa0e423ce94c494fa3bf /include | |
| parent | 5e87d8ee34e32fda720f3a4e4055f570b09230d6 (diff) | |
mm: avoid null pointer access in vm_struct via /proc/vmallocinfo
commit f5252e009d5b87071a919221e4f6624184005368 upstream
The /proc/vmallocinfo shows information about vmalloc allocations in vmlist
that is a linklist of vm_struct. It, however, may access pages field of
vm_struct where a page was not allocated. This results in a null pointer
access and leads to a kernel panic.
Why this happen:
In __vmalloc_node() called from vmalloc(), newly allocated vm_struct
is added to vmlist at __get_vm_area_node() and then, some fields of
vm_struct such as nr_pages and pages are set at __vmalloc_area_node(). In
other words, it is added to vmlist before it is fully initialized. At the
same time, when the /proc/vmallocinfo is read, it accesses the pages field
of vm_struct according to the nr_pages field at show_numa_info(). Thus, a
null pointer access happens.
Patch:
This patch adds newly allocated vm_struct to the vmlist *after* it is fully
initialized. So, it can avoid accessing the pages field with unallocated
page when show_numa_info() is called.
Signed-off-by: Mitsuo Hayasaka <mitsuo.hayasaka.hu@hitachi.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: David Rientjes <rientjes@google.com>
Cc: Namhyung Kim <namhyung@gmail.com>
Cc: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
Cc: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
Diffstat (limited to 'include')
| -rw-r--r-- | include/linux/vmalloc.h | 1 |
1 files changed, 1 insertions, 0 deletions
diff --git a/include/linux/vmalloc.h b/include/linux/vmalloc.h index 3c123c35c94..819a6346ac5 100644 --- a/include/linux/vmalloc.h +++ b/include/linux/vmalloc.h @@ -13,6 +13,7 @@ struct vm_area_struct; /* vma defining user mapping in mm_types.h */ #define VM_MAP 0x00000004 /* vmap()ed pages */ #define VM_USERMAP 0x00000008 /* suitable for remap_vmalloc_range */ #define VM_VPAGES 0x00000010 /* buffer for pages was vmalloc'ed */ +#define VM_UNLIST 0x00000020 /* vm_struct is not listed in vmlist */ /* bits [20..32] reserved for arch specific ioremap internals */ /* |