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linux/net/dccp
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Wang Liang c3d052cae5 net: fix data-races around sk->sk_forward_alloc 
commit 073d89808c upstream.

Syzkaller reported this warning:
 ------------[ cut here ]------------
 WARNING: CPU: 0 PID: 16 at net/ipv4/af_inet.c:156 inet_sock_destruct+0x1c5/0x1e0
 Modules linked in:
 CPU: 0 UID: 0 PID: 16 Comm: ksoftirqd/0 Not tainted 6.12.0-rc5 #26
 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.15.0-1 04/01/2014
 RIP: 0010:inet_sock_destruct+0x1c5/0x1e0
 Code: 24 12 4c 89 e2 5b 48 c7 c7 98 ec bb 82 41 5c e9 d1 18 17 ff 4c 89 e6 5b 48 c7 c7 d0 ec bb 82 41 5c e9 bf 18 17 ff 0f 0b eb 83 <0f> 0b eb 97 0f 0b eb 87 0f 0b e9 68 ff ff ff 66 66 2e 0f 1f 84 00
 RSP: 0018:ffffc9000008bd90 EFLAGS: 00010206
 RAX: 0000000000000300 RBX: ffff88810b172a90 RCX: 0000000000000007
 RDX: 0000000000000002 RSI: 0000000000000300 RDI: ffff88810b172a00
 RBP: ffff88810b172a00 R08: ffff888104273c00 R09: 0000000000100007
 R10: 0000000000020000 R11: 0000000000000006 R12: ffff88810b172a00
 R13: 0000000000000004 R14: 0000000000000000 R15: ffff888237c31f78
 FS:  0000000000000000(0000) GS:ffff888237c00000(0000) knlGS:0000000000000000
 CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
 CR2: 00007ffc63fecac8 CR3: 000000000342e000 CR4: 00000000000006f0
 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
 Call Trace:
  <TASK>
  ? __warn+0x88/0x130
  ? inet_sock_destruct+0x1c5/0x1e0
  ? report_bug+0x18e/0x1a0
  ? handle_bug+0x53/0x90
  ? exc_invalid_op+0x18/0x70
  ? asm_exc_invalid_op+0x1a/0x20
  ? inet_sock_destruct+0x1c5/0x1e0
  __sk_destruct+0x2a/0x200
  rcu_do_batch+0x1aa/0x530
  ? rcu_do_batch+0x13b/0x530
  rcu_core+0x159/0x2f0
  handle_softirqs+0xd3/0x2b0
  ? __pfx_smpboot_thread_fn+0x10/0x10
  run_ksoftirqd+0x25/0x30
  smpboot_thread_fn+0xdd/0x1d0
  kthread+0xd3/0x100
  ? __pfx_kthread+0x10/0x10
  ret_from_fork+0x34/0x50
  ? __pfx_kthread+0x10/0x10
  ret_from_fork_asm+0x1a/0x30
  </TASK>
 ---[ end trace 0000000000000000 ]---

Its possible that two threads call tcp_v6_do_rcv()/sk_forward_alloc_add()
concurrently when sk->sk_state == TCP_LISTEN with sk->sk_lock unlocked,
which triggers a data-race around sk->sk_forward_alloc:
tcp_v6_rcv
    tcp_v6_do_rcv
        skb_clone_and_charge_r
            sk_rmem_schedule
                __sk_mem_schedule
                    sk_forward_alloc_add()
            skb_set_owner_r
                sk_mem_charge
                    sk_forward_alloc_add()
        __kfree_skb
            skb_release_all
                skb_release_head_state
                    sock_rfree
                        sk_mem_uncharge
                            sk_forward_alloc_add()
                            sk_mem_reclaim
                                // set local var reclaimable
                                __sk_mem_reclaim
                                    sk_forward_alloc_add()

In this syzkaller testcase, two threads call
tcp_v6_do_rcv() with skb->truesize=768, the sk_forward_alloc changes like
this:
 (cpu 1)             | (cpu 2)             | sk_forward_alloc
 ...                 | ...                 | 0
 __sk_mem_schedule() |                     | +4096 = 4096
                     | __sk_mem_schedule() | +4096 = 8192
 sk_mem_charge()     |                     | -768  = 7424
                     | sk_mem_charge()     | -768  = 6656
 ...                 |    ...              |
 sk_mem_uncharge()   |                     | +768  = 7424
 reclaimable=7424    |                     |
                     | sk_mem_uncharge()   | +768  = 8192
                     | reclaimable=8192    |
 __sk_mem_reclaim()  |                     | -4096 = 4096
                     | __sk_mem_reclaim()  | -8192 = -4096 != 0

The skb_clone_and_charge_r() should not be called in tcp_v6_do_rcv() when
sk->sk_state is TCP_LISTEN, it happens later in tcp_v6_syn_recv_sock().
Fix the same issue in dccp_v6_do_rcv().

Suggested-by: Eric Dumazet <edumazet@google.com>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Fixes: e994b2f0fb ("tcp: do not lock listener to process SYN packets")
Signed-off-by: Wang Liang <wangliang74@huawei.com>
Link: https://patch.msgid.link/20241107023405.889239-1-wangliang74@huawei.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Alva Lan <alvalan9@foxmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
History 2025-01-23 17:16:04 +01:00
..
ccids dccp: tfrc: fix doc warnings in tfrc_equation.c 2021-06-10 14:08:49 -07:00
ackvec.c net: dccp: Fix most of the kerneldoc warnings 2020-10-30 12:08:54 -07:00
ackvec.h treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 500 2019-06-19 17:09:55 +02:00
ccid.c net: dccp: Add __printf() markup to fix -Wsuggest-attribute=format 2020-10-30 11:31:46 -07:00
ccid.h net: dccp: Replace zero-length array with flexible-array member 2020-02-28 12:08:37 -08:00
dccp.h dccp: Call inet6_destroy_sock() via sk->sk_destruct(). 2023-04-26 13:51:54 +02:00
diag.c inet_diag: Move the INET_DIAG_REQ_BYTECODE nlattr to cb->data 2020-02-27 18:50:19 -08:00
feat.c dccp: Fix memory leak in dccp_feat_change_recv 2024-12-14 19:51:27 +01:00
feat.h treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 500 2019-06-19 17:09:55 +02:00
input.c net: dccp: Convert to use the preferred fallthrough macro 2020-08-22 12:38:34 -07:00
ipv4.c Fix race for duplicate reqsk on identical SYN 2024-07-05 09:14:41 +02:00
ipv6.c net: fix data-races around sk->sk_forward_alloc 2025-01-23 17:16:04 +01:00
ipv6.h treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 500 2019-06-19 17:09:55 +02:00
Kconfig dccp: Replace HTTP links with HTTPS ones 2020-07-13 11:54:07 -07:00
Makefile net: dccp: Remove dccpprobe module 2018-01-02 14:27:30 -05:00
minisocks.c dccp: don't duplicate ccid when cloning dccp sock 2021-09-08 11:28:35 +01:00
options.c net: dccp: Convert to use the preferred fallthrough macro 2020-08-22 12:38:34 -07:00
output.c dccp: fix data-race around dp->dccps_mss_cache 2023-08-16 18:22:01 +02:00
proto.c net: inet: Retire port only listening_hash 2023-11-28 16:56:22 +00:00
qpolicy.c net: dccp: Fix most of the kerneldoc warnings 2020-10-30 12:08:54 -07:00
sysctl.c proc/sysctl: add shared variables for range check 2019-07-18 17:08:07 -07:00
timer.c net: sock: introduce sk_error_report 2021-06-29 11:28:21 -07:00
trace.h net: dccp: Add DCCP sendmsg trace event 2018-01-02 14:27:30 -05:00