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authorMitsuo Hayasaka <mitsuo.hayasaka.hu@hitachi.com>2011-11-01 01:08:13 +0100
committerLinus Torvalds <torvalds@linux-foundation.org>2011-11-01 01:30:47 +0100
commitf5252e009d5b87071a919221e4f6624184005368 (patch)
tree4be380e99c468dcb10597c445eb6b801897eafea /mm/memblock.c
parentmm/debug-pagealloc.c: use memchr_inv (diff)
downloadlinux-f5252e009d5b87071a919221e4f6624184005368.tar.xz
linux-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 'mm/memblock.c')
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