kasan: don't assume percpu shadow allocations will succeed
syzkaller and the fault injector showed that I was wrong to assume that we could ignore percpu shadow allocation failures. Handle failures properly. Merge all the allocated areas back into the free list and release the shadow, then clean up and return NULL. The shadow is released unconditionally, which relies upon the fact that the release function is able to tolerate pages not being present. Also clean up shadows in the recovery path - currently they are not released, which leaks a bit of memory. Link: http://lkml.kernel.org/r/20191205140407.1874-3-dja@axtens.net Fixes: 3c5c3cfb ("kasan: support backing vmalloc space with real shadow memory") Signed-off-by: Daniel Axtens <dja@axtens.net> Reported-by: syzbot+82e323920b78d54aaed5@syzkaller.appspotmail.com Reported-by: syzbot+59b7daa4315e07a994f1@syzkaller.appspotmail.com Reviewed-by: Andrey Ryabinin <aryabinin@virtuozzo.com> Cc: Dmitry Vyukov <dvyukov@google.com> Cc: Alexander Potapenko <glider@google.com> Cc: Qian Cai <cai@lca.pw> Cc: Uladzislau Rezki (Sony) <urezki@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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