From: Christian Brauner <christian.brauner@ubuntu.com>
To: syzbot <syzbot+dfac92a50024b54acaa4@syzkaller.appspotmail.com>
Cc: akpm@linux-foundation.org, cxfcosmos@gmail.com,
ebiederm@xmission.com, glider@google.com, legion@kernel.org,
linux-kernel@vger.kernel.org, serge@hallyn.com,
syzkaller-bugs@googlegroups.com
Subject: Re: [syzbot] KMSAN: uninit-value in from_kuid
Date: Mon, 29 Nov 2021 12:47:13 +0100 [thread overview]
Message-ID: <20211129114713.at2mo64hgnlmkx3x@wittgenstein> (raw)
In-Reply-To: <000000000000a0d53f05d1c72a4c@google.com>
On Sat, Nov 27, 2021 at 07:50:27AM -0800, syzbot wrote:
> Hello,
>
> syzbot found the following issue on:
>
> HEAD commit: 425295055ce6 kmsan: core: address comments to kmsan-checks.h
> git tree: https://github.com/google/kmsan.git master
> console output: https://syzkaller.appspot.com/x/log.txt?x=1640209ab00000
> kernel config: https://syzkaller.appspot.com/x/.config?x=2d142cdf4204061
> dashboard link: https://syzkaller.appspot.com/bug?extid=dfac92a50024b54acaa4
> compiler: clang version 14.0.0 (git@github.com:llvm/llvm-project.git 0996585c8e3b3d409494eb5f1cad714b9e1f7fb5), GNU ld (GNU Binutils for Debian) 2.35.2
> userspace arch: i386
>
> Unfortunately, I don't have any reproducer for this issue yet.
>
> IMPORTANT: if you fix the issue, please add the following tag to the commit:
> Reported-by: syzbot+dfac92a50024b54acaa4@syzkaller.appspotmail.com
>
> =====================================================
> BUG: KMSAN: uninit-value in map_id_up_base kernel/user_namespace.c:335 [inline]
> BUG: KMSAN: uninit-value in map_id_up kernel/user_namespace.c:365 [inline]
> BUG: KMSAN: uninit-value in from_kuid+0x51d/0xbd0 kernel/user_namespace.c:413
> map_id_up_base kernel/user_namespace.c:335 [inline]
> map_id_up kernel/user_namespace.c:365 [inline]
> from_kuid+0x51d/0xbd0 kernel/user_namespace.c:413
> p9pdu_vwritef+0x15ab/0x5120 net/9p/protocol.c:398
> p9pdu_writef+0x23a/0x280 net/9p/protocol.c:539
> p9pdu_vwritef+0x21f0/0x5120 net/9p/protocol.c:490
> p9_client_prepare_req+0xa4b/0xff0 net/9p/client.c:709
> p9_client_rpc+0x278/0x1410 net/9p/client.c:740
> p9_client_setattr+0x115/0x2c0 net/9p/client.c:1899
> v9fs_vfs_setattr_dotl+0x7e2/0xd70 fs/9p/vfs_inode_dotl.c:590
> notify_change+0x1fe3/0x2170 fs/attr.c:410
> vfs_utimes+0x8aa/0xc70 fs/utimes.c:65
> do_utimes_path fs/utimes.c:98 [inline]
> do_utimes fs/utimes.c:144 [inline]
> __do_sys_utime32 fs/utimes.c:247 [inline]
> __se_sys_utime32+0x386/0x520 fs/utimes.c:235
> __ia32_sys_utime32+0x91/0xc0 fs/utimes.c:235
> do_syscall_32_irqs_on arch/x86/entry/common.c:114 [inline]
> __do_fast_syscall_32+0x96/0xf0 arch/x86/entry/common.c:180
> do_fast_syscall_32+0x34/0x70 arch/x86/entry/common.c:205
> do_SYSENTER_32+0x1b/0x20 arch/x86/entry/common.c:248
> entry_SYSENTER_compat_after_hwframe+0x4d/0x5c
>
> Uninit was stored to memory at:
> v9fs_vfs_setattr_dotl+0x58a/0xd70 fs/9p/vfs_inode_dotl.c:567
That's a bug in the 9P2000.L implementation of .setattr.
It copies struct iattr values without checking ia_valid. That's causing
uninitalized memory to be copied. I sent a fix to 9p for this.
Christian
next prev parent reply other threads:[~2021-11-29 13:04 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-11-27 15:50 syzbot
2021-11-29 11:47 ` Christian Brauner [this message]
2021-11-29 12:03 ` Alexander Potapenko
2021-11-29 15:16 ` Alexander Potapenko
2021-11-29 15:52 ` Christian Brauner
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