From: Dominique Martinet <asmadeus@codewreck.org>
To: syzbot <syzbot+e441aeeb422763cc5511@syzkaller.appspotmail.com>
Cc: davem@davemloft.net, edumazet@google.com, ericvh@kernel.org,
kuba@kernel.org, linux-fsdevel@vger.kernel.org,
linux-kernel@vger.kernel.org, linux_oss@crudebyte.com,
lucho@ionkov.net, netdev@vger.kernel.org, pabeni@redhat.com,
syzkaller-bugs@googlegroups.com, v9fs@lists.linux.dev
Subject: Re: [syzbot] [net?] [v9fs?] KCSAN: data-race in p9_fd_create / p9_fd_create (2)
Date: Tue, 29 Aug 2023 19:57:24 +0900 [thread overview]
Message-ID: <ZO3PFO_OpNfBW7bd@codewreck.org> (raw)
In-Reply-To: <000000000000d26ff606040c9719@google.com>
syzbot wrote on Tue, Aug 29, 2023 at 02:39:53AM -0700:
> ==================================================================
> BUG: KCSAN: data-race in p9_fd_create / p9_fd_create
>
> read-write to 0xffff888130fb3d48 of 4 bytes by task 15599 on cpu 0:
> p9_fd_open net/9p/trans_fd.c:842 [inline]
> p9_fd_create+0x210/0x250 net/9p/trans_fd.c:1092
> p9_client_create+0x595/0xa70 net/9p/client.c:1010
> v9fs_session_init+0xf9/0xd90 fs/9p/v9fs.c:410
> v9fs_mount+0x69/0x630 fs/9p/vfs_super.c:123
> legacy_get_tree+0x74/0xd0 fs/fs_context.c:611
> vfs_get_tree+0x51/0x190 fs/super.c:1519
> do_new_mount+0x203/0x660 fs/namespace.c:3335
> path_mount+0x496/0xb30 fs/namespace.c:3662
> do_mount fs/namespace.c:3675 [inline]
> __do_sys_mount fs/namespace.c:3884 [inline]
> __se_sys_mount+0x27f/0x2d0 fs/namespace.c:3861
> __x64_sys_mount+0x67/0x80 fs/namespace.c:3861
> 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-write to 0xffff888130fb3d48 of 4 bytes by task 15563 on cpu 1:
> p9_fd_open net/9p/trans_fd.c:842 [inline]
> p9_fd_create+0x210/0x250 net/9p/trans_fd.c:1092
> p9_client_create+0x595/0xa70 net/9p/client.c:1010
> v9fs_session_init+0xf9/0xd90 fs/9p/v9fs.c:410
> v9fs_mount+0x69/0x630 fs/9p/vfs_super.c:123
> legacy_get_tree+0x74/0xd0 fs/fs_context.c:611
> vfs_get_tree+0x51/0x190 fs/super.c:1519
> do_new_mount+0x203/0x660 fs/namespace.c:3335
> path_mount+0x496/0xb30 fs/namespace.c:3662
> do_mount fs/namespace.c:3675 [inline]
> __do_sys_mount fs/namespace.c:3884 [inline]
> __se_sys_mount+0x27f/0x2d0 fs/namespace.c:3861
> __x64_sys_mount+0x67/0x80 fs/namespace.c:3861
> 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: 0x00008002 -> 0x00008802
Yes well that doesn't seem too hard to hit, both threads are just
setting O_NONBLOCK to the same fd in parallel (0x800 is 04000,
O_NONBLOCK)
I'm not quite sure why that'd be a problem; and I'm also pretty sure
that wouldn't work anyway (9p has no muxing or anything that'd allow
sharing the same fd between multiple mounts)
Can this be flagged "don't care" ?
--
Dominique Martinet | Asmadeus
next prev parent reply other threads:[~2023-08-29 11:05 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-08-29 9:39 [syzbot] [net?] [v9fs?] KCSAN: data-race in p9_fd_create / p9_fd_create (2) syzbot
2023-08-29 10:57 ` Dominique Martinet [this message]
2023-08-29 14:11 ` Marco Elver
2023-08-29 23:05 ` Dominique Martinet
2023-08-30 7:59 ` Marco Elver
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