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| author | Mitsuo Hayasaka <mitsuo.hayasaka.hu@hitachi.com> | 2011-10-31 17:08:13 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2011-10-31 17:30:47 -0700 |
| commit | f5252e009d5b87071a919221e4f6624184005368 (patch) | |
| tree | 4be380e99c468dcb10597c445eb6b801897eafea /include/linux/vmalloc.h | |
| parent | 8c5fb8eadde41f67c61a7ac2d3246dab87bf7020 (diff) | |
| download | lwn-f5252e009d5b87071a919221e4f6624184005368.tar.gz lwn-f5252e009d5b87071a919221e4f6624184005368.zip | |
mm: avoid null pointer access in vm_struct via /proc/vmallocinfo
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 happens: In __vmalloc_node_range() 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.
The patch adds the 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>
Cc: <stable@kernel.org>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'include/linux/vmalloc.h')
| -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 9332e52ea8c2..687fb11e2010 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 */ /* |