Messages in this thread | | | Date | Mon, 07 Nov 2011 22:07:03 +0900 | From | HAYASAKA Mitsuo <> | Subject | Re: mm: avoid null pointer access in vm_struct via /proc/vmallocinfo |
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Hi Greg,
> So, if someone wants this patch there, could they please provide me with > a backported version?
I'd like to send the patch for backport version.
Regards,
(2011/11/03 4:19), Greg KH wrote: > Is this patch also relevant for the .32-stable tree? I tried to > backport it, and only got one conflict, but I'm still not sure I got it > correct. > > So, if someone wants this patch there, could they please provide me with > a backported version? > > thanks, > > greg k-h > > On Mon, Oct 31, 2011 at 05:08:13PM -0700, Mitsuo Hayasaka wrote: >> From: Mitsuo Hayasaka <mitsuo.hayasaka.hu@hitachi.com> >> >> 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 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> >> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> >> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> >> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de> >> >> --- 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 */ >> >> /* >> diff --git a/mm/vmalloc.c b/mm/vmalloc.c >> index 5016f19..56faf31 100644 >> --- a/mm/vmalloc.c >> +++ b/mm/vmalloc.c >> @@ -1253,18 +1253,22 @@ EXPORT_SYMBOL_GPL(map_vm_area); >> DEFINE_RWLOCK(vmlist_lock); >> struct vm_struct *vmlist; >> >> -static void insert_vmalloc_vm(struct vm_struct *vm, struct vmap_area *va, >> +static void setup_vmalloc_vm(struct vm_struct *vm, struct vmap_area *va, >> unsigned long flags, void *caller) >> { >> - struct vm_struct *tmp, **p; >> - >> vm->flags = flags; >> vm->addr = (void *)va->va_start; >> vm->size = va->va_end - va->va_start; >> vm->caller = caller; >> va->private = vm; >> va->flags |= VM_VM_AREA; >> +} >> + >> +static void insert_vmalloc_vmlist(struct vm_struct *vm) >> +{ >> + struct vm_struct *tmp, **p; >> >> + vm->flags &= ~VM_UNLIST; >> write_lock(&vmlist_lock); >> for (p = &vmlist; (tmp = *p) != NULL; p = &tmp->next) { >> if (tmp->addr >= vm->addr) >> @@ -1275,6 +1279,13 @@ static void insert_vmalloc_vm(struct vm_struct *vm, struct vmap_area *va, >> write_unlock(&vmlist_lock); >> } >> >> +static void insert_vmalloc_vm(struct vm_struct *vm, struct vmap_area *va, >> + unsigned long flags, void *caller) >> +{ >> + setup_vmalloc_vm(vm, va, flags, caller); >> + insert_vmalloc_vmlist(vm); >> +} >> + >> static struct vm_struct *__get_vm_area_node(unsigned long size, >> unsigned long align, unsigned long flags, unsigned long start, >> unsigned long end, int node, gfp_t gfp_mask, void *caller) >> @@ -1313,7 +1324,18 @@ static struct vm_struct *__get_vm_area_node(unsigned long size, >> return NULL; >> } >> >> - insert_vmalloc_vm(area, va, flags, caller); >> + /* >> + * When this function is called from __vmalloc_node_range, >> + * we do not add vm_struct to vmlist here to avoid >> + * accessing uninitialized members of vm_struct such as >> + * pages and nr_pages fields. They will be set later. >> + * To distinguish it from others, we use a VM_UNLIST flag. >> + */ >> + if (flags & VM_UNLIST) >> + setup_vmalloc_vm(area, va, flags, caller); >> + else >> + insert_vmalloc_vm(area, va, flags, caller); >> + >> return area; >> } >> >> @@ -1381,17 +1403,20 @@ struct vm_struct *remove_vm_area(const void *addr) >> va = find_vmap_area((unsigned long)addr); >> if (va && va->flags & VM_VM_AREA) { >> struct vm_struct *vm = va->private; >> - struct vm_struct *tmp, **p; >> - /* >> - * remove from list and disallow access to this vm_struct >> - * before unmap. (address range confliction is maintained by >> - * vmap.) >> - */ >> - write_lock(&vmlist_lock); >> - for (p = &vmlist; (tmp = *p) != vm; p = &tmp->next) >> - ; >> - *p = tmp->next; >> - write_unlock(&vmlist_lock); >> + >> + if (!(vm->flags & VM_UNLIST)) { >> + struct vm_struct *tmp, **p; >> + /* >> + * remove from list and disallow access to >> + * this vm_struct before unmap. (address range >> + * confliction is maintained by vmap.) >> + */ >> + write_lock(&vmlist_lock); >> + for (p = &vmlist; (tmp = *p) != vm; p = &tmp->next) >> + ; >> + *p = tmp->next; >> + write_unlock(&vmlist_lock); >> + } >> >> vmap_debug_free_range(va->va_start, va->va_end); >> free_unmap_vmap_area(va); >> @@ -1602,8 +1627,8 @@ void *__vmalloc_node_range(unsigned long size, unsigned long align, >> if (!size || (size >> PAGE_SHIFT) > totalram_pages) >> return NULL; >> >> - area = __get_vm_area_node(size, align, VM_ALLOC, start, end, node, >> - gfp_mask, caller); >> + area = __get_vm_area_node(size, align, VM_ALLOC | VM_UNLIST, >> + start, end, node, gfp_mask, caller); >> >> if (!area) >> return NULL; >> @@ -1611,6 +1636,12 @@ void *__vmalloc_node_range(unsigned long size, unsigned long align, >> addr = __vmalloc_area_node(area, gfp_mask, prot, node, caller); >> >> /* >> + * In this function, newly allocated vm_struct is not added >> + * to vmlist at __get_vm_area_node(). so, it is added here. >> + */ >> + insert_vmalloc_vmlist(area); >> + >> + /* >> * A ref_count = 3 is needed because the vm_struct and vmap_area >> * structures allocated in the __get_vm_area_node() function contain >> * references to the virtual address of the vmalloc'ed block. >
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