Messages in this thread | | | Date | Tue, 30 Jul 2019 16:17:52 -0400 | From | Sasha Levin <> | Subject | Re: [PATCH stable 4.9] tcp: reset sk_send_head in tcp_write_queue_purge |
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On Tue, Jul 30, 2019 at 09:31:19AM +0800, maowenan wrote: > > >On 2019/7/29 23:32, Sasha Levin wrote: >> On Mon, Jul 29, 2019 at 09:21:08PM +0800, Mao Wenan wrote: >>> From: Soheil Hassas Yeganeh <soheil@google.com> >>> >>> tcp_write_queue_purge clears all the SKBs in the write queue >>> but does not reset the sk_send_head. As a result, we can have >>> a NULL pointer dereference anywhere that we use tcp_send_head >>> instead of the tcp_write_queue_tail. >>> >>> For example, after a27fd7a8ed38 (tcp: purge write queue upon RST), >>> we can purge the write queue on RST. Prior to >>> 75c119afe14f (tcp: implement rb-tree based retransmit queue), >>> tcp_push will only check tcp_send_head and then accesses >>> tcp_write_queue_tail to send the actual SKB. As a result, it will >>> dereference a NULL pointer. >>> >>> This has been reported twice for 4.14 where we don't have >>> 75c119afe14f: >>> >>> By Timofey Titovets: >>> >>> [ 422.081094] BUG: unable to handle kernel NULL pointer dereference >>> at 0000000000000038 >>> [ 422.081254] IP: tcp_push+0x42/0x110 >>> [ 422.081314] PGD 0 P4D 0 >>> [ 422.081364] Oops: 0002 [#1] SMP PTI >>> >>> By Yongjian Xu: >>> >>> BUG: unable to handle kernel NULL pointer dereference at 0000000000000038 >>> IP: tcp_push+0x48/0x120 >>> PGD 80000007ff77b067 P4D 80000007ff77b067 PUD 7fd989067 PMD 0 >>> Oops: 0002 [#18] SMP PTI >>> Modules linked in: tcp_diag inet_diag tcp_bbr sch_fq iTCO_wdt >>> iTCO_vendor_support pcspkr ixgbe mdio i2c_i801 lpc_ich joydev input_leds shpchp >>> e1000e igb dca ptp pps_core hwmon mei_me mei ipmi_si ipmi_msghandler sg ses >>> scsi_transport_sas enclosure ext4 jbd2 mbcache sd_mod ahci libahci megaraid_sas >>> wmi ast ttm dm_mirror dm_region_hash dm_log dm_mod dax >>> CPU: 6 PID: 14156 Comm: [ET_NET 6] Tainted: G D 4.14.26-1.el6.x86_64 #1 >>> Hardware name: LENOVO ThinkServer RD440 /ThinkServer RD440, BIOS A0TS80A >>> 09/22/2014 >>> task: ffff8807d78d8140 task.stack: ffffc9000e944000 >>> RIP: 0010:tcp_push+0x48/0x120 >>> RSP: 0018:ffffc9000e947a88 EFLAGS: 00010246 >>> RAX: 00000000000005b4 RBX: ffff880f7cce9c00 RCX: 0000000000000000 >>> RDX: 0000000000000000 RSI: 0000000000000040 RDI: ffff8807d00f5000 >>> RBP: ffffc9000e947aa8 R08: 0000000000001c84 R09: 0000000000000000 >>> R10: ffff8807d00f5158 R11: 0000000000000000 R12: ffff8807d00f5000 >>> R13: 0000000000000020 R14: 00000000000256d4 R15: 0000000000000000 >>> FS: 00007f5916de9700(0000) GS:ffff88107fd00000(0000) knlGS:0000000000000000 >>> CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 >>> CR2: 0000000000000038 CR3: 00000007f8226004 CR4: 00000000001606e0 >>> Call Trace: >>> tcp_sendmsg_locked+0x33d/0xe50 >>> tcp_sendmsg+0x37/0x60 >>> inet_sendmsg+0x39/0xc0 >>> sock_sendmsg+0x49/0x60 >>> sock_write_iter+0xb6/0x100 >>> do_iter_readv_writev+0xec/0x130 >>> ? rw_verify_area+0x49/0xb0 >>> do_iter_write+0x97/0xd0 >>> vfs_writev+0x7e/0xe0 >>> ? __wake_up_common_lock+0x80/0xa0 >>> ? __fget_light+0x2c/0x70 >>> ? __do_page_fault+0x1e7/0x530 >>> do_writev+0x60/0xf0 >>> ? inet_shutdown+0xac/0x110 >>> SyS_writev+0x10/0x20 >>> do_syscall_64+0x6f/0x140 >>> ? prepare_exit_to_usermode+0x8b/0xa0 >>> entry_SYSCALL_64_after_hwframe+0x3d/0xa2 >>> RIP: 0033:0x3135ce0c57 >>> RSP: 002b:00007f5916de4b00 EFLAGS: 00000293 ORIG_RAX: 0000000000000014 >>> RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 0000003135ce0c57 >>> RDX: 0000000000000002 RSI: 00007f5916de4b90 RDI: 000000000000606f >>> RBP: 0000000000000000 R08: 0000000000000000 R09: 00007f5916de8c38 >>> R10: 0000000000000000 R11: 0000000000000293 R12: 00000000000464cc >>> R13: 00007f5916de8c30 R14: 00007f58d8bef080 R15: 0000000000000002 >>> Code: 48 8b 97 60 01 00 00 4c 8d 97 58 01 00 00 41 b9 00 00 00 00 41 89 f3 4c 39 >>> d2 49 0f 44 d1 41 81 e3 00 80 00 00 0f 85 b0 00 00 00 <80> 4a 38 08 44 8b 8f 74 >>> 06 00 00 44 89 8f 7c 06 00 00 83 e6 01 >>> RIP: tcp_push+0x48/0x120 RSP: ffffc9000e947a88 >>> CR2: 0000000000000038 >>> ---[ end trace 8d545c2e93515549 ]--- >>> >>> There is other scenario which found in stable 4.4: >>> Allocated: >>> [<ffffffff82f380a6>] __alloc_skb+0xe6/0x600 net/core/skbuff.c:218 >>> [<ffffffff832466c3>] alloc_skb_fclone include/linux/skbuff.h:856 [inline] >>> [<ffffffff832466c3>] sk_stream_alloc_skb+0xa3/0x5d0 net/ipv4/tcp.c:833 >>> [<ffffffff83249164>] tcp_sendmsg+0xd34/0x2b00 net/ipv4/tcp.c:1178 >>> [<ffffffff83300ef3>] inet_sendmsg+0x203/0x4d0 net/ipv4/af_inet.c:755 >>> Freed: >>> [<ffffffff82f372fd>] __kfree_skb+0x1d/0x20 net/core/skbuff.c:676 >>> [<ffffffff83288834>] sk_wmem_free_skb include/net/sock.h:1447 [inline] >>> [<ffffffff83288834>] tcp_write_queue_purge include/net/tcp.h:1460 [inline] >>> [<ffffffff83288834>] tcp_connect_init net/ipv4/tcp_output.c:3122 [inline] >>> [<ffffffff83288834>] tcp_connect+0xb24/0x30c0 net/ipv4/tcp_output.c:3261 >>> [<ffffffff8329b991>] tcp_v4_connect+0xf31/0x1890 net/ipv4/tcp_ipv4.c:246 >>> >>> BUG: KASAN: use-after-free in tcp_skb_pcount include/net/tcp.h:796 [inline] >>> BUG: KASAN: use-after-free in tcp_init_tso_segs net/ipv4/tcp_output.c:1619 [inline] >>> BUG: KASAN: use-after-free in tcp_write_xmit+0x3fc2/0x4cb0 net/ipv4/tcp_output.c:2056 >>> [<ffffffff81515cd5>] kasan_report.cold.7+0x175/0x2f7 mm/kasan/report.c:408 >>> [<ffffffff814f9784>] __asan_report_load2_noabort+0x14/0x20 mm/kasan/report.c:427 >>> [<ffffffff83286582>] tcp_skb_pcount include/net/tcp.h:796 [inline] >>> [<ffffffff83286582>] tcp_init_tso_segs net/ipv4/tcp_output.c:1619 [inline] >>> [<ffffffff83286582>] tcp_write_xmit+0x3fc2/0x4cb0 net/ipv4/tcp_output.c:2056 >>> [<ffffffff83287a40>] __tcp_push_pending_frames+0xa0/0x290 net/ipv4/tcp_output.c:2307 >>> >>> stable 4.4 and stable 4.9 don't have the commit abb4a8b870b5 ("tcp: purge write queue upon RST") >>> which is referred in dbbf2d1e4077, >>> in tcp_connect_init, it calls tcp_write_queue_purge, and does not reset sk_send_head, then UAF. >>> >>> stable 4.14 have the commit abb4a8b870b5 ("tcp: purge write queue upon RST"), >>> in tcp_reset, it calls tcp_write_queue_purge(sk), and does not reset sk_send_head, then UAF. >>> >>> So this patch can be used to fix stable 4.4 and 4.9. >>> >>> Fixes: a27fd7a8ed38 (tcp: purge write queue upon RST) >>> Reported-by: Timofey Titovets <nefelim4ag@gmail.com> >>> Reported-by: Yongjian Xu <yongjianchn@gmail.com> >>> Signed-off-by: Eric Dumazet <edumazet@google.com> >>> Signed-off-by: Soheil Hassas Yeganeh <soheil@google.com> >>> Tested-by: Yongjian Xu <yongjianchn@gmail.com> >>> >>> Signed-off-by: David S. Miller <davem@davemloft.net> >>> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> >>> Signed-off-by: Mao Wenan <maowenan@huawei.com> >> >> So the "Fixes:" commit in the commit message is wrong? What's the actual >> commit that this fixes? > >Upstream commit is 7f582b248d0a ("tcp: purge write queue in tcp_connect_init()") >linux-4.4.y >Fixes: 5bbe138a250e ("tcp: purge write queue in tcp_connect_init()") >linux-4.9.y >Fixes: 74a4c09d4b05 ("tcp: purge write queue in tcp_connect_init()") >linux-4.14.y >Fixes: a27fd7a8ed38 ("tcp: purge write queue upon RST")
Okay, I've queued this for 4.9 and 4.4, thank you.
-- Thanks, Sasha
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