From nobody Sat Feb 7 05:52:29 2026 Received: from exchange.fintech.ru (exchange.fintech.ru [195.54.195.159]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id B475584A2B for ; Mon, 8 Apr 2024 14:11:27 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=195.54.195.159 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1712585491; cv=none; b=q+PGlRNMniLGqYHpW6Pecp7pP/5IY02MAaL4ERJ7V84HMGrRnzwuMuNjSLfmveWuqFGA5CuUzW8O+G+OhUBk1nAbWVvSKGKKoNdcrZlsC6ohNPJRPfK1W/fkBmfUYvm6FGH3+BsbmhWjZS4+06UGeEALZJNy3eIdOFNnaff2Sn8= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1712585491; c=relaxed/simple; bh=eLXvdEPZ7Cv9E/VbzgBBf1ggcn+8mLUZyZt/b335WQ0=; h=From:To:CC:Subject:Date:Message-ID:MIME-Version:Content-Type; b=PAUTUVl0/MXrIuC6zLSgr3qJ5Vb5WDcOMi/nHIRIwYIr5Ywad81yZDvfHFLafbfGJD2fth6nSJAA1He39C8uB4f7S0gzj7BIc+4emhs9vQiBV9LU3CmHUPEI2b66rsiRRYiyIpgzte8SVGOU6FrrMWa87wee/n2tpqY71lWPbhg= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=fintech.ru; spf=pass smtp.mailfrom=fintech.ru; arc=none smtp.client-ip=195.54.195.159 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=fintech.ru Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=fintech.ru Received: from Ex16-01.fintech.ru (10.0.10.18) by exchange.fintech.ru (195.54.195.169) with Microsoft SMTP Server (TLS) id 14.3.498.0; Mon, 8 Apr 2024 17:11:19 +0300 Received: from localhost (10.0.253.138) by Ex16-01.fintech.ru (10.0.10.18) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2242.4; Mon, 8 Apr 2024 17:11:19 +0300 From: Nikita Zhandarovich To: Eric Van Hensbergen CC: Nikita Zhandarovich , Latchesar Ionkov , Dominique Martinet , "Christian Schoenebeck" , , , , Subject: [PATCH net v2] net/9p: fix uninit-value in p9_client_rpc() Date: Mon, 8 Apr 2024 07:10:39 -0700 Message-ID: <20240408141039.30428-1-n.zhandarovich@fintech.ru> X-Mailer: git-send-email 2.25.1 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-ClientProxiedBy: Ex16-02.fintech.ru (10.0.10.19) To Ex16-01.fintech.ru (10.0.10.18) Content-Type: text/plain; charset="utf-8" Syzbot with the help of KMSAN reported the following error: BUG: KMSAN: uninit-value in trace_9p_client_res include/trace/events/9p.h:1= 46 [inline] BUG: KMSAN: uninit-value in p9_client_rpc+0x1314/0x1340 net/9p/client.c:754 trace_9p_client_res include/trace/events/9p.h:146 [inline] p9_client_rpc+0x1314/0x1340 net/9p/client.c:754 p9_client_create+0x1551/0x1ff0 net/9p/client.c:1031 v9fs_session_init+0x1b9/0x28e0 fs/9p/v9fs.c:410 v9fs_mount+0xe2/0x12b0 fs/9p/vfs_super.c:122 legacy_get_tree+0x114/0x290 fs/fs_context.c:662 vfs_get_tree+0xa7/0x570 fs/super.c:1797 do_new_mount+0x71f/0x15e0 fs/namespace.c:3352 path_mount+0x742/0x1f20 fs/namespace.c:3679 do_mount fs/namespace.c:3692 [inline] __do_sys_mount fs/namespace.c:3898 [inline] __se_sys_mount+0x725/0x810 fs/namespace.c:3875 __x64_sys_mount+0xe4/0x150 fs/namespace.c:3875 do_syscall_64+0xd5/0x1f0 entry_SYSCALL_64_after_hwframe+0x6d/0x75 Uninit was created at: __alloc_pages+0x9d6/0xe70 mm/page_alloc.c:4598 __alloc_pages_node include/linux/gfp.h:238 [inline] alloc_pages_node include/linux/gfp.h:261 [inline] alloc_slab_page mm/slub.c:2175 [inline] allocate_slab mm/slub.c:2338 [inline] new_slab+0x2de/0x1400 mm/slub.c:2391 ___slab_alloc+0x1184/0x33d0 mm/slub.c:3525 __slab_alloc mm/slub.c:3610 [inline] __slab_alloc_node mm/slub.c:3663 [inline] slab_alloc_node mm/slub.c:3835 [inline] kmem_cache_alloc+0x6d3/0xbe0 mm/slub.c:3852 p9_tag_alloc net/9p/client.c:278 [inline] p9_client_prepare_req+0x20a/0x1770 net/9p/client.c:641 p9_client_rpc+0x27e/0x1340 net/9p/client.c:688 p9_client_create+0x1551/0x1ff0 net/9p/client.c:1031 v9fs_session_init+0x1b9/0x28e0 fs/9p/v9fs.c:410 v9fs_mount+0xe2/0x12b0 fs/9p/vfs_super.c:122 legacy_get_tree+0x114/0x290 fs/fs_context.c:662 vfs_get_tree+0xa7/0x570 fs/super.c:1797 do_new_mount+0x71f/0x15e0 fs/namespace.c:3352 path_mount+0x742/0x1f20 fs/namespace.c:3679 do_mount fs/namespace.c:3692 [inline] __do_sys_mount fs/namespace.c:3898 [inline] __se_sys_mount+0x725/0x810 fs/namespace.c:3875 __x64_sys_mount+0xe4/0x150 fs/namespace.c:3875 do_syscall_64+0xd5/0x1f0 entry_SYSCALL_64_after_hwframe+0x6d/0x75 If p9_check_errors() fails early in p9_client_rpc(), req->rc.tag will not be properly initialized. However, trace_9p_client_res() ends up trying to print it out anyway before p9_client_rpc() finishes. Fix this issue by assigning default values to p9_fcall fields such as 'tag' and (just in case KMSAN unearths something new) 'id' during the tag allocation stage. Reported-and-tested-by: syzbot+ff14db38f56329ef68df@syzkaller.appspotmail.c= om Fixes: 348b59012e5c ("net/9p: Convert net/9p protocol dumps to tracepoints") Signed-off-by: Nikita Zhandarovich Reviewed-by: Christian Schoenebeck --- v2: change fc->tag init value from 0 to P9_NOTAG per Dominique Martinet's helpful suggestion. Link: https://lore.kernel.org/all/ZhNVMivKCCq6wir0@codewreck.org/ net/9p/client.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/net/9p/client.c b/net/9p/client.c index f7e90b4769bb..b05f73c291b4 100644 --- a/net/9p/client.c +++ b/net/9p/client.c @@ -235,6 +235,8 @@ static int p9_fcall_init(struct p9_client *c, struct p9= _fcall *fc, if (!fc->sdata) return -ENOMEM; fc->capacity =3D alloc_msize; + fc->id =3D 0; + fc->tag =3D P9_NOTAG; return 0; }