Messages in this thread | | | Date | Mon, 17 Jun 2019 16:40:31 +0200 | From | Roman Penyaev <> | Subject | Re: [BUG]: mm/vmalloc: uninitialized variable access in pcpu_get_vm_areas |
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On 2019-06-17 16:04, Arnd Bergmann wrote: > On Mon, Jun 17, 2019 at 3:49 PM Roman Penyaev <rpenyaev@suse.de> wrote: >> > augment_tree_propagate_from(va); >> > >> > - if (type == NE_FIT_TYPE) >> > - insert_vmap_area_augment(lva, &va->rb_node, >> > - &free_vmap_area_root, &free_vmap_area_list); >> > - } >> > - >> > return 0; >> > } >> >> >> Hi Arnd, >> >> Seems the proper fix is just setting lva to NULL. The only place >> where lva is allocated and then used is when type == NE_FIT_TYPE, >> so according to my shallow understanding of the code everything >> should be fine. > > I don't see how NULL could work here. insert_vmap_area_augment() > passes the va pointer into find_va_links() and link_va(), both of > which dereference the pointer, see
Exactly, but insert_vmap_area_augement() accepts 'va', not 'lva', but in your variant 'va' is already freed (see type == FL_FIT_TYPE branch, on top of that function). So that should be use-after-free.
-- Roman
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