KCSAN: data-race in __alloc_file / __alloc

KCSAN: data-race in __alloc_file / __alloc_file
Status: auto-closed as invalid on 2020/01/19 03:08
Reported-by: syzbot+3ef049d50587836c0606@syzkaller.appspotmail.com
First crash: 458d, last: 441d

Sample crash report:

==================================================================
BUG: KCSAN: data-race in __alloc_file / __alloc_file

write to 0xffff8880b609cd58 of 4 bytes by task 23698 on cpu 0:
 get_cred include/linux/cred.h:253 [inline]
 __alloc_file+0x74/0x210 fs/file_table.c:105
 alloc_empty_file+0x8f/0x180 fs/file_table.c:151
 alloc_file+0x4e/0x2b0 fs/file_table.c:193
 alloc_file_pseudo+0x11c/0x1b0 fs/file_table.c:232
 create_pipe_files+0x22a/0x380 fs/pipe.c:776
 __do_pipe_flags+0x51/0x180 fs/pipe.c:807
 do_pipe2+0x3f/0x150 fs/pipe.c:855
 __do_sys_pipe fs/pipe.c:878 [inline]
 __se_sys_pipe fs/pipe.c:876 [inline]
 __x64_sys_pipe+0x2a/0x40 fs/pipe.c:876
 do_syscall_64+0xcc/0x370 arch/x86/entry/common.c:290
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

write to 0xffff8880b609cd58 of 4 bytes by task 23692 on cpu 1:
 get_cred include/linux/cred.h:253 [inline]
 __alloc_file+0x74/0x210 fs/file_table.c:105
 alloc_empty_file+0x8f/0x180 fs/file_table.c:151
 alloc_file+0x4e/0x2b0 fs/file_table.c:193
 alloc_file_pseudo+0x11c/0x1b0 fs/file_table.c:232
 sock_alloc_file+0x65/0x120 net/socket.c:397
 sock_map_fd net/socket.c:420 [inline]
 __sys_socket+0xe8/0x170 net/socket.c:1515
 __do_sys_socket net/socket.c:1520 [inline]
 __se_sys_socket net/socket.c:1518 [inline]
 __x64_sys_socket+0x4c/0x60 net/socket.c:1518
 do_syscall_64+0xcc/0x370 arch/x86/entry/common.c:290
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 23692 Comm: syz-executor.3 Not tainted 5.4.0-rc6+ #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
==================================================================

Crashes (12):
Manager	Time	Kernel	Commit	Syzkaller	Config	Log	Report	Maintainers
ci2-upstream-kcsan-gce	2019/11/10 03:07	https://github.com/google/ktsan.git kcsan	94c00660	dc438b91	.config	log	report	linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, viro@zeniv.linux.org.uk
ci2-upstream-kcsan-gce	2019/11/07 17:22	https://github.com/google/ktsan.git kcsan	94c00660	f39aff9e	.config	log	report	linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, viro@zeniv.linux.org.uk
ci2-upstream-kcsan-gce	2019/11/07 05:16	https://github.com/google/ktsan.git kcsan	94c00660	d797d201	.config	log	report	linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, viro@zeniv.linux.org.uk
ci2-upstream-kcsan-gce	2019/11/05 18:09	https://github.com/google/ktsan.git kcsan	94c00660	af5c522d	.config	log	report	linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, viro@zeniv.linux.org.uk
ci2-upstream-kcsan-gce	2019/11/04 23:04	https://github.com/google/ktsan.git kcsan	94c00660	18e12644	.config	log	report	linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, viro@zeniv.linux.org.uk
ci2-upstream-kcsan-gce	2019/11/02 23:23	https://github.com/google/ktsan.git kcsan	05f22368	d603afc9	.config	log	report	linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, viro@zeniv.linux.org.uk
ci2-upstream-kcsan-gce	2019/11/01 21:21	https://github.com/google/ktsan.git kcsan	05f22368	997ccc67	.config	log	report	linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, viro@zeniv.linux.org.uk
ci2-upstream-kcsan-gce	2019/10/30 21:54	https://github.com/google/ktsan.git kcsan	05f22368	a41ca8fa	.config	log	report	linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, viro@zeniv.linux.org.uk
ci2-upstream-kcsan-gce	2019/10/28 19:14	https://github.com/google/ktsan.git kcsan	05f22368	439d7b14	.config	log	report	linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, viro@zeniv.linux.org.uk
ci2-upstream-kcsan-gce	2019/10/26 13:45	https://github.com/google/ktsan.git kcsan	05f22368	25bb509e	.config	log	report	linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, viro@zeniv.linux.org.uk
ci2-upstream-kcsan-gce	2019/10/26 07:29	https://github.com/google/ktsan.git kcsan	05f22368	413926c5	.config	log	report	linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, viro@zeniv.linux.org.uk
ci2-upstream-kcsan-gce	2019/10/24 08:17	https://github.com/google/ktsan.git kcsan	05f22368	d01bb02a	.config	log	report	linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, viro@zeniv.linux.org.uk