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Message-ID: <c6eaf667-fd03-cdf4-b4c4-1b1e80cfa604@gmail.com>
Date:   Mon, 1 Mar 2021 17:50:33 +0100
From:   Eric Dumazet <eric.dumazet@...il.com>
To:     Stephen Hemminger <stephen@...workplumber.org>,
        netdev@...r.kernel.org, Pavel Emelyanov <xemul@...allels.com>
Subject: Re: Fw: [Bug 212005] New: WARNING: CPU: 1 PID: 356 at
 net/ipv4/tcp.c:2343 tcp_recvmsg_locked+0x90e/0x29a0



On 3/1/21 5:37 PM, Eric Dumazet wrote:
> 
> 
> On 3/1/21 4:58 PM, Stephen Hemminger wrote:
>>
>>
>> Begin forwarded message:
>>
>> Date: Mon, 01 Mar 2021 11:50:22 +0000
>> From: bugzilla-daemon@...zilla.kernel.org
>> To: stephen@...workplumber.org
>> Subject: [Bug 212005] New: WARNING: CPU: 1 PID: 356 at net/ipv4/tcp.c:2343 tcp_recvmsg_locked+0x90e/0x29a0
>>
>>
>> https://bugzilla.kernel.org/show_bug.cgi?id=212005
>>
>>             Bug ID: 212005
>>            Summary: WARNING: CPU: 1 PID: 356 at net/ipv4/tcp.c:2343
>>                     tcp_recvmsg_locked+0x90e/0x29a0
>>            Product: Networking
>>            Version: 2.5
>>     Kernel Version: 5.11.0-rc7+
>>           Hardware: Intel
>>                 OS: Linux
>>               Tree: Mainline
>>             Status: NEW
>>           Severity: normal
>>           Priority: P1
>>          Component: IPV4
>>           Assignee: stephen@...workplumber.org
>>           Reporter: ieatmuttonchuan@...il.com
>>         Regression: No
>>
>> Created attachment 295545
>>   --> https://bugzilla.kernel.org/attachment.cgi?id=295545&action=edit  
>> poc C file
>>
>> Hello,
>> I found a bug in kernel version 5.11.0-rc7+.
>> This is the POC.
>> 1.Git clone git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
>> 2.Build kernel with CONFIG_KASAN
>> 3.Run kernel with qemu
>> ```
>> qemu-system-x86_64 \
>>         -m 1G \
>>         -smp 2 \
>>         -kernel bzImage \
>>         -append "console=ttyS0 root=/dev/sda earlyprintk=serial net.ifnames=0"
>> \
>>         -drive file=stretch.img,format=raw \
>>         -net user,host=10.0.2.10,hostfwd=tcp:127.0.0.1:1569-:22 \
>>         -net nic,model=e1000 \
>>         -nographic \
>>         -enable-kvm
>> ```
>> 4.Compile POC and scp into qemu.
>> ```
>> gcc tcp_recvmsg_locked.c -static -lpthread
>> scp -P 1569 a.out root@...alhost:~
>> ```
>> 5.Run a.out you will see the dump log.
>> ```
>> root@...kaller:~# ./a.out 
>> [  111.196095] audit: type=1400 audit(1614585907.556:8): avc:  denied  {
>> execmem } for  pid=356 comm="a.out" scontext=system_u:system_r:kernel_t:s0
>> tcontext=system_u:system_r:kernel_t:s0 tclass=process permissive=1
>> [  111.203295] ------------[ cut here ]------------
>> [  111.205099] TCP recvmsg seq # bug 2: copied 80, seq 0, rcvnxt 80, fl 0
>> [  111.207894] WARNING: CPU: 1 PID: 356 at net/ipv4/tcp.c:2343
>> tcp_recvmsg_locked+0x90e/0x29a0
>> [  111.212756] Modules linked in:
>> [  111.214115] CPU: 1 PID: 356 Comm: a.out Not tainted 5.11.0-rc7+ #1
>> [  111.216911] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS
>> 1.10.2-1ubuntu1 04/01/2014
>> [  111.220464] RIP: 0010:tcp_recvmsg_locked+0x90e/0x29a0
>> [  111.222596] Code: 48 c1 e8 03 0f b6 04 18 84 c0 0f 85 18 01 00 00 8b 0a 48
>> c7 c7 60 04 d0 86 44 89 fe 89 ea 44 8b 44 24 2c 31 c0 e8 32 3d c3 fd <0f> 0b e9
>> 2e ff ff ff e8 76 f2 eb fd c6 05 29 7d bf 01 01 48 c7 c7
>> [  111.228525] RSP: 0018:ffff888001a4fab8 EFLAGS: 00010246
>> [  111.229905] RAX: f2b8163648339800 RBX: dffffc0000000000 RCX:
>> ffff8880035b9c00
>> [  111.232193] RDX: 0000000000000000 RSI: 0000000000000000 RDI:
>> 0000000000000000
>> [  111.234829] RBP: 0000000000000000 R08: ffffffff83928cd0 R09:
>> ffffed10061a5d1a
>> [  111.236645] R10: ffffed10061a5d1a R11: 0000000000000000 R12:
>> 00000000ffffff94
>> [  111.238287] R13: ffff888001ed0b68 R14: 1ffff110003da16d R15:
>> 0000000000000080
>> [  111.239721] FS:  00000000010da880(0000) GS:ffff888030d00000(0000)
>> knlGS:0000000000000000
>> [  111.241303] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
>> [  111.242461] CR2: 00000000004608dd CR3: 0000000003948000 CR4:
>> 00000000000006e0
>> [  111.243806] DR0: 0000000000000000 DR1: 0000000000000000 DR2:
>> 0000000000000000
>> [  111.245072] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7:
>> 0000000000000400
>> [  111.246337] Call Trace:
>> [  111.246775]  tcp_recvmsg+0x1c9/0xd50
>> [  111.247397]  ? memset+0x1f/0x40
>> [  111.247978]  ? selinux_socket_recvmsg+0xaf/0x240
>> [  111.248820]  ? tcp_v6_do_rcv+0x542/0x1280
>> [  111.249415]  ? tcp_mmap+0xc0/0xc0
>> [  111.249966]  inet6_recvmsg+0x107/0x480
>> [  111.250509]  ? inet6_sendmsg+0x120/0x120
>> [  111.251101]  __sys_recvfrom+0x34d/0x530
>> [  111.251695]  ? do_tcp_setsockopt+0x2381/0x33d0
>> [  111.252447]  ? tcp_setsockopt+0x3a/0xf0
>> [  111.253339]  ? __sys_setsockopt+0x1fd/0x270
>> [  111.254743]  ? sock_common_recvmsg+0x190/0x190
>> [  111.256106]  ? __sys_setsockopt+0x211/0x270
>> [  111.256693]  __x64_sys_recvfrom+0xda/0xf0
>> [  111.257430]  do_syscall_64+0x33/0x40
>> [  111.258145]  entry_SYSCALL_64_after_hwframe+0x44/0xa9
>> [  111.259133] RIP: 0033:0x449cb9
>> [  111.259646] Code: 00 b8 00 01 00 00 eb e1 e8 f4 19 00 00 0f 1f 40 00 48 89
>> f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01
>> f0 ff ff 73 01 c3 48 c7 c1 c0 ff ff ff f7 d8 64 89 01 48
>> [  111.262498] RSP: 002b:00007fffaa2b0328 EFLAGS: 00000212 ORIG_RAX:
>> 000000000000002d
>> [  111.263615] RAX: ffffffffffffffda RBX: 0000000020000050 RCX:
>> 0000000000449cb9
>> [  111.264686] RDX: 0000000000000014 RSI: 0000000000000000 RDI:
>> 0000000000000003
>> [  111.265573] RBP: 00007fffaa2b0360 R08: 0000000000000000 R09:
>> 0000000000000000
>> [  111.266342] R10: 0000000000000000 R11: 0000000000000212 R12:
>> 0000000000401cb0
>> [  111.267090] R13: 0000000000000000 R14: 00000000006b9018 R15:
>> 0000000000000000
>> [  111.267838] ---[ end trace 3bc6b032cf6c31f5 ]---
>> [  111.268332] ------------[ cut here ]------------
>> [  111.268873] cleanup rbuf bug: copied 80 seq 14 rcvnxt 80
>> [  111.269477] WARNING: CPU: 1 PID: 356 at net/ipv4/tcp.c:1555
>> tcp_cleanup_rbuf+0x3f4/0x5a0
>> [  111.270330] Modules linked in:
>> [  111.270655] CPU: 1 PID: 356 Comm: a.out Tainted: G        W        
>> 5.11.0-rc7+ #1
>> [  111.271445] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS
>> 1.10.2-1ubuntu1 04/01/2014
>> [  111.272370] RIP: 0010:tcp_cleanup_rbuf+0x3f4/0x5a0
>> [  111.272886] Code: b9 00 00 00 00 00 fc ff df 8a 04 08 84 c0 0f 85 9a 01 00
>> 00 41 8b 0c 24 48 c7 c7 60 ff cf 86 89 ee 89 da 31 c0 e8 0c 70 c3 fd <0f> 0b e9
>> a5 fc ff ff 44 89 e9 80 e1 07 38 c1 0f 8c bb fc ff ff 4c
>> [  111.274834] RSP: 0018:ffff888001a4fa78 EFLAGS: 00010246
>> [  111.275404] RAX: f2b8163648339800 RBX: 0000000000000014 RCX:
>> ffff8880035b9c00
>> [  111.276148] RDX: 0000000000000000 RSI: 0000000000000001 RDI:
>> 0000000000000000
>> [  111.276890] RBP: 0000000000000080 R08: ffffffff83a84a02 R09:
>> ffffed10061a3f23
>> [  111.277702] R10: ffffed10061a3f23 R11: 0000000000000000 R12:
>> ffff8880075e0570
>> [  111.278560] R13: ffff888001ed0b68 R14: 00000000ffffff98 R15:
>> ffff8880075e0000
>> [  111.279307] FS:  00000000010da880(0000) GS:ffff888030d00000(0000)
>> knlGS:0000000000000000
>> [  111.280261] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
>> [  111.280866] CR2: 00000000004608dd CR3: 0000000003948000 CR4:
>> 00000000000006e0
>> [  111.281594] DR0: 0000000000000000 DR1: 0000000000000000 DR2:
>> 0000000000000000
>> [  111.282495] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7:
>> 0000000000000400
>> [  111.283815] Call Trace:
>> [  111.284275]  tcp_recvmsg_locked+0x2206/0x29a0
>> [  111.285467]  tcp_recvmsg+0x1c9/0xd50
>> [  111.285979]  ? memset+0x1f/0x40
>> [  111.286394]  ? selinux_socket_recvmsg+0xaf/0x240
>> [  111.286996]  ? tcp_v6_do_rcv+0x542/0x1280
>> [  111.287431]  ? tcp_mmap+0xc0/0xc0
>> [  111.287895]  inet6_recvmsg+0x107/0x480
>> [  111.288313]  ? inet6_sendmsg+0x120/0x120
>> [  111.288888]  __sys_recvfrom+0x34d/0x530
>> [  111.289391]  ? do_tcp_setsockopt+0x2381/0x33d0
>> [  111.289954]  ? tcp_setsockopt+0x3a/0xf0
>> [  111.290429]  ? __sys_setsockopt+0x1fd/0x270
>> [  111.290942]  ? sock_common_recvmsg+0x190/0x190
>> [  111.291416]  ? __sys_setsockopt+0x211/0x270
>> [  111.291871]  __x64_sys_recvfrom+0xda/0xf0
>> [  111.292323]  do_syscall_64+0x33/0x40
>> [  111.292700]  entry_SYSCALL_64_after_hwframe+0x44/0xa9
>> [  111.293240] RIP: 0033:0x449cb9
>> [  111.293567] Code: 00 b8 00 01 00 00 eb e1 e8 f4 19 00 00 0f 1f 40 00 48 89
>> f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01
>> f0 ff ff 73 01 c3 48 c7 c1 c0 ff ff ff f7 d8 64 89 01 48
>> [  111.295468] RSP: 002b:00007fffaa2b0328 EFLAGS: 00000212 ORIG_RAX:
>> 000000000000002d
>> [  111.296323] RAX: ffffffffffffffda RBX: 0000000020000050 RCX:
>> 0000000000449cb9
>> [  111.297142] RDX: 0000000000000014 RSI: 0000000000000000 RDI:
>> 0000000000000003
>> [  111.298007] RBP: 00007fffaa2b0360 R08: 0000000000000000 R09:
>> 0000000000000000
>> [  111.298718] R10: 0000000000000000 R11: 0000000000000212 R12:
>> 0000000000401cb0
>> [  111.299475] R13: 0000000000000000 R14: 00000000006b9018 R15:
>> 0000000000000000
>> [  111.300202] ---[ end trace 3bc6b032cf6c31f6 ]---
>> ```
>>
> 
> 
> Well, another TCP_REPAIR bug.
> 

Repro is :
mprotect(0x4aa000, 12288, PROT_READ)    = 0
mmap(0x1ffff000, 4096, PROT_NONE, MAP_PRIVATE|MAP_FIXED|MAP_ANONYMOUS, -1, 0) = 0x1ffff000
mmap(0x20000000, 16777216, PROT_READ|PROT_WRITE|PROT_EXEC, MAP_PRIVATE|MAP_FIXED|MAP_ANONYMOUS, -1, 0) = 0x20000000
mmap(0x21000000, 4096, PROT_NONE, MAP_PRIVATE|MAP_FIXED|MAP_ANONYMOUS, -1, 0) = 0x21000000
socket(AF_INET6, SOCK_STREAM, IPPROTO_IP) = 3
setsockopt(3, SOL_TCP, TCP_REPAIR, [1], 4) = 0
connect(3, {sa_family=AF_INET6, sin6_port=htons(0), sin6_flowinfo=htonl(0), inet_pton(AF_INET6, "::1", &sin6_addr), sin6_scope_id=0}, 28) = 0
setsockopt(3, SOL_TCP, TCP_REPAIR_QUEUE, [1], 4) = 0
sendmsg(3, {msg_name=NULL, msg_namelen=0, msg_iov=[{iov_base="0x0000000000000003\0\0", iov_len=20}], msg_iovlen=1, msg_controllen=0, msg_flags=0}, 0) = 20
setsockopt(3, SOL_TCP, TCP_REPAIR, [0], 4) = 0
setsockopt(3, SOL_TCP, TCP_QUEUE_SEQ, [128], 4) = 0
recvfrom(3, NULL, 20, 0, NULL, NULL)    = -1 ECONNRESET (Connection reset by peer)


I guess the following patch would fix this specific report,
but we also have to look at the write queue side (TCP_SEND_QUEUE)

diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c
index a3422e42784edfedeecd7e9cfe6ed68990c90957..79759e2480bda0a9052316a6850c616edb90ab4c 100644
--- a/net/ipv4/tcp.c
+++ b/net/ipv4/tcp.c
@@ -3474,8 +3474,12 @@ static int do_tcp_setsockopt(struct sock *sk, int level, int optname,
                else if (tp->repair_queue == TCP_SEND_QUEUE)
                        WRITE_ONCE(tp->write_seq, val);
                else if (tp->repair_queue == TCP_RECV_QUEUE) {
-                       WRITE_ONCE(tp->rcv_nxt, val);
-                       WRITE_ONCE(tp->copied_seq, val);
+                       if (tp->rcv_nxt != tp->copied_seq) {
+                               err = -EINVAL;
+                       } else {
+                               WRITE_ONCE(tp->rcv_nxt, val);
+                               WRITE_ONCE(tp->copied_seq, val);
+                       }
                }
                else
                        err = -EINVAL;

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