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KCSAN: data-race in dccp_connect / dccp_sendmsg (3)

Status: fixed on 2023/10/12 12:48
Subsystems: dccp
[Documentation on labels]
Fix commit: a47e598fbd86 dccp: fix data-race around dp->dccps_mss_cache
First crash: 316d, last: 316d
Similar bugs (2)
Kernel Title Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream KCSAN: data-race in dccp_connect / dccp_sendmsg (2) dccp 1 930d 930d 0/27 auto-closed as invalid on 2022/01/01 06:39
upstream KCSAN: data-race in dccp_connect / dccp_sendmsg dccp 1 1328d 1328d 0/27 auto-closed as invalid on 2020/11/29 18:07

Sample crash report:
==================================================================
BUG: KCSAN: data-race in dccp_connect / dccp_sendmsg

write to 0xffff88814c2d05d4 of 4 bytes by task 7495 on cpu 1:
 dccp_sync_mss net/dccp/output.c:190 [inline]
 dccp_connect+0x17e/0x3d0 net/dccp/output.c:551
 dccp_v4_connect+0x738/0x7c0 net/dccp/ipv4.c:135
 __inet_stream_connect+0x15d/0x720 net/ipv4/af_inet.c:666
 inet_stream_connect+0x48/0x70 net/ipv4/af_inet.c:730
 __sys_connect_file net/socket.c:1992 [inline]
 __sys_connect+0x1a1/0x1b0 net/socket.c:2009
 __do_sys_connect net/socket.c:2019 [inline]
 __se_sys_connect net/socket.c:2016 [inline]
 __x64_sys_connect+0x41/0x50 net/socket.c:2016
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x41/0xc0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x63/0xcd

read to 0xffff88814c2d05d4 of 4 bytes by task 7497 on cpu 0:
 dccp_sendmsg+0x63/0x4b0 net/dccp/proto.c:742
 inet_sendmsg+0x63/0x80 net/ipv4/af_inet.c:830
 sock_sendmsg_nosec net/socket.c:725 [inline]
 sock_sendmsg net/socket.c:748 [inline]
 __sys_sendto+0x257/0x310 net/socket.c:2134
 __do_sys_sendto net/socket.c:2146 [inline]
 __se_sys_sendto net/socket.c:2142 [inline]
 __x64_sys_sendto+0x78/0x90 net/socket.c:2142
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x41/0xc0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x63/0xcd

value changed: 0x00000218 -> 0x0000ffc3

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 7497 Comm: syz-executor.3 Not tainted 6.5.0-rc4-syzkaller-00041-gec351c8f2e62 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/12/2023
==================================================================

Crashes (1):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2023/08/03 07:51 upstream ec351c8f2e62 39a91c18 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in dccp_connect / dccp_sendmsg
* Struck through repros no longer work on HEAD.