| From 2baae3545327632167c0180e9ca1d467416f1919 Mon Sep 17 00:00:00 2001 |
| From: Eric Dumazet <edumazet@google.com> |
| Date: Mon, 13 May 2019 09:59:16 -0700 |
| Subject: bpf: devmap: fix use-after-free Read in __dev_map_entry_free |
| MIME-Version: 1.0 |
| Content-Type: text/plain; charset=UTF-8 |
| Content-Transfer-Encoding: 8bit |
| |
| From: Eric Dumazet <edumazet@google.com> |
| |
| commit 2baae3545327632167c0180e9ca1d467416f1919 upstream. |
| |
| synchronize_rcu() is fine when the rcu callbacks only need |
| to free memory (kfree_rcu() or direct kfree() call rcu call backs) |
| |
| __dev_map_entry_free() is a bit more complex, so we need to make |
| sure that call queued __dev_map_entry_free() callbacks have completed. |
| |
| sysbot report: |
| |
| BUG: KASAN: use-after-free in dev_map_flush_old kernel/bpf/devmap.c:365 |
| [inline] |
| BUG: KASAN: use-after-free in __dev_map_entry_free+0x2a8/0x300 |
| kernel/bpf/devmap.c:379 |
| Read of size 8 at addr ffff8801b8da38c8 by task ksoftirqd/1/18 |
| |
| CPU: 1 PID: 18 Comm: ksoftirqd/1 Not tainted 4.17.0+ #39 |
| Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS |
| Google 01/01/2011 |
| Call Trace: |
| __dump_stack lib/dump_stack.c:77 [inline] |
| dump_stack+0x1b9/0x294 lib/dump_stack.c:113 |
| print_address_description+0x6c/0x20b mm/kasan/report.c:256 |
| kasan_report_error mm/kasan/report.c:354 [inline] |
| kasan_report.cold.7+0x242/0x2fe mm/kasan/report.c:412 |
| __asan_report_load8_noabort+0x14/0x20 mm/kasan/report.c:433 |
| dev_map_flush_old kernel/bpf/devmap.c:365 [inline] |
| __dev_map_entry_free+0x2a8/0x300 kernel/bpf/devmap.c:379 |
| __rcu_reclaim kernel/rcu/rcu.h:178 [inline] |
| rcu_do_batch kernel/rcu/tree.c:2558 [inline] |
| invoke_rcu_callbacks kernel/rcu/tree.c:2818 [inline] |
| __rcu_process_callbacks kernel/rcu/tree.c:2785 [inline] |
| rcu_process_callbacks+0xe9d/0x1760 kernel/rcu/tree.c:2802 |
| __do_softirq+0x2e0/0xaf5 kernel/softirq.c:284 |
| run_ksoftirqd+0x86/0x100 kernel/softirq.c:645 |
| smpboot_thread_fn+0x417/0x870 kernel/smpboot.c:164 |
| kthread+0x345/0x410 kernel/kthread.c:240 |
| ret_from_fork+0x3a/0x50 arch/x86/entry/entry_64.S:412 |
| |
| Allocated by task 6675: |
| save_stack+0x43/0xd0 mm/kasan/kasan.c:448 |
| set_track mm/kasan/kasan.c:460 [inline] |
| kasan_kmalloc+0xc4/0xe0 mm/kasan/kasan.c:553 |
| kmem_cache_alloc_trace+0x152/0x780 mm/slab.c:3620 |
| kmalloc include/linux/slab.h:513 [inline] |
| kzalloc include/linux/slab.h:706 [inline] |
| dev_map_alloc+0x208/0x7f0 kernel/bpf/devmap.c:102 |
| find_and_alloc_map kernel/bpf/syscall.c:129 [inline] |
| map_create+0x393/0x1010 kernel/bpf/syscall.c:453 |
| __do_sys_bpf kernel/bpf/syscall.c:2351 [inline] |
| __se_sys_bpf kernel/bpf/syscall.c:2328 [inline] |
| __x64_sys_bpf+0x303/0x510 kernel/bpf/syscall.c:2328 |
| do_syscall_64+0x1b1/0x800 arch/x86/entry/common.c:290 |
| entry_SYSCALL_64_after_hwframe+0x49/0xbe |
| |
| Freed by task 26: |
| save_stack+0x43/0xd0 mm/kasan/kasan.c:448 |
| set_track mm/kasan/kasan.c:460 [inline] |
| __kasan_slab_free+0x11a/0x170 mm/kasan/kasan.c:521 |
| kasan_slab_free+0xe/0x10 mm/kasan/kasan.c:528 |
| __cache_free mm/slab.c:3498 [inline] |
| kfree+0xd9/0x260 mm/slab.c:3813 |
| dev_map_free+0x4fa/0x670 kernel/bpf/devmap.c:191 |
| bpf_map_free_deferred+0xba/0xf0 kernel/bpf/syscall.c:262 |
| process_one_work+0xc64/0x1b70 kernel/workqueue.c:2153 |
| worker_thread+0x181/0x13a0 kernel/workqueue.c:2296 |
| kthread+0x345/0x410 kernel/kthread.c:240 |
| ret_from_fork+0x3a/0x50 arch/x86/entry/entry_64.S:412 |
| |
| The buggy address belongs to the object at ffff8801b8da37c0 |
| which belongs to the cache kmalloc-512 of size 512 |
| The buggy address is located 264 bytes inside of |
| 512-byte region [ffff8801b8da37c0, ffff8801b8da39c0) |
| The buggy address belongs to the page: |
| page:ffffea0006e368c0 count:1 mapcount:0 mapping:ffff8801da800940 |
| index:0xffff8801b8da3540 |
| flags: 0x2fffc0000000100(slab) |
| raw: 02fffc0000000100 ffffea0007217b88 ffffea0006e30cc8 ffff8801da800940 |
| raw: ffff8801b8da3540 ffff8801b8da3040 0000000100000004 0000000000000000 |
| page dumped because: kasan: bad access detected |
| |
| Memory state around the buggy address: |
| ffff8801b8da3780: fc fc fc fc fc fc fc fc fb fb fb fb fb fb fb fb |
| ffff8801b8da3800: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb |
| > ffff8801b8da3880: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb |
| ^ |
| ffff8801b8da3900: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb |
| ffff8801b8da3980: fb fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc |
| |
| Fixes: 546ac1ffb70d ("bpf: add devmap, a map for storing net device references") |
| Signed-off-by: Eric Dumazet <edumazet@google.com> |
| Reported-by: syzbot+457d3e2ffbcf31aee5c0@syzkaller.appspotmail.com |
| Acked-by: Toke Høiland-Jørgensen <toke@redhat.com> |
| Acked-by: Jesper Dangaard Brouer <brouer@redhat.com> |
| Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> |
| Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> |
| |
| --- |
| kernel/bpf/devmap.c | 3 +++ |
| 1 file changed, 3 insertions(+) |
| |
| --- a/kernel/bpf/devmap.c |
| +++ b/kernel/bpf/devmap.c |
| @@ -164,6 +164,9 @@ static void dev_map_free(struct bpf_map |
| bpf_clear_redirect_map(map); |
| synchronize_rcu(); |
| |
| + /* Make sure prior __dev_map_entry_free() have completed. */ |
| + rcu_barrier(); |
| + |
| /* To ensure all pending flush operations have completed wait for flush |
| * bitmap to indicate all flush_needed bits to be zero on _all_ cpus. |
| * Because the above synchronize_rcu() ensures the map is disconnected |