From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mx0b-001b2d01.pphosted.com ([148.163.158.5]:59535 "EHLO mx0a-001b2d01.pphosted.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1751006AbcFJRHq (ORCPT ); Fri, 10 Jun 2016 13:07:46 -0400 Received: from pps.filterd (m0098416.ppops.net [127.0.0.1]) by mx0b-001b2d01.pphosted.com (8.16.0.11/8.16.0.11) with SMTP id u5AH4GAQ071824 for ; Fri, 10 Jun 2016 13:07:46 -0400 Received: from e06smtp06.uk.ibm.com (e06smtp06.uk.ibm.com [195.75.94.102]) by mx0b-001b2d01.pphosted.com with ESMTP id 23g1e7rbk6-1 (version=TLSv1.2 cipher=AES256-SHA bits=256 verify=NOT) for ; Fri, 10 Jun 2016 13:07:46 -0400 Received: from localhost by e06smtp06.uk.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Fri, 10 Jun 2016 18:07:44 +0100 From: Laurent Dufour To: autofs@vger.kernel.org Cc: Ian Kent , linux-kernel@vger.kernel.org, stable@vger.kernel.org Subject: [PATCH] autofs4: Fix endless loop in autofs4_write Date: Fri, 10 Jun 2016 19:07:39 +0200 Message-Id: <1465578459-8624-1-git-send-email-ldufour@linux.vnet.ibm.com> Sender: stable-owner@vger.kernel.org List-ID: The 'commit e9a7c2f1a548 ("autofs4: coding style fixes")' removed the check done on the __vfs_write()'s returned value in autofs4_write(). This may lead to a spinning process which can't catch any signal. Call stack showed in xmon could be : [c0000003a76c7500] c00000000030df74 __vfs_write+0x134/0x1c0 (unreliable) [c0000003a76c75a0] d0000000052a35d4 autofs4_notify_daemon+0x174/0x3f0 [autofs4] [c0000003a76c7780] d0000000052a3fa0 autofs4_wait+0x750/0xa10 [autofs4] [c0000003a76c78b0] d0000000052a24d8 autofs4_mount_wait+0x78/0x140 [autofs4] [c0000003a76c7930] d0000000052a2f48 autofs4_d_automount+0x1d8/0x370 [autofs4] [c0000003a76c79c0] c0000000003221e4 follow_managed+0x204/0x3a0 [c0000003a76c7a20] c000000000322c10 lookup_fast+0x220/0x420 [c0000003a76c7a90] c00000000032324c walk_component+0x5c/0x3e0 [c0000003a76c7b00] c000000000323794 link_path_walk+0x1c4/0x5f0 [c0000003a76c7b90] c000000000324b00 path_openat+0xf0/0x1620 [c0000003a76c7c90] c000000000327f6c do_filp_open+0xfc/0x170 [c0000003a76c7dc0] c00000000030d06c do_sys_open+0x1bc/0x2e0 [c0000003a76c7e30] c000000000009260 system_call+0x38/0x108 --- Exception: c01 (System Call) at 00003fffa38a0988 Cc: Ian Kent Cc: autofs@vger.kernel.org Cc: linux-kernel@vger.kernel.org Cc: stable@vger.kernel.org Reviewed-by: Greg Kurz Signed-off-by: Laurent Dufour Fixes: e9a7c2f1a548 ("autofs4: coding style fixes") --- fs/autofs4/waitq.c | 7 ++++--- 1 file changed, 4 insertions(+), 3 deletions(-) diff --git a/fs/autofs4/waitq.c b/fs/autofs4/waitq.c index 0146d911f468..106d94139281 100644 --- a/fs/autofs4/waitq.c +++ b/fs/autofs4/waitq.c @@ -66,11 +66,12 @@ static int autofs4_write(struct autofs_sb_info *sbi, set_fs(KERNEL_DS); mutex_lock(&sbi->pipe_mutex); - wr = __vfs_write(file, data, bytes, &file->f_pos); - while (bytes && wr) { + while (bytes) { + wr = __vfs_write(file, data, bytes, &file->f_pos); + if (wr < 0) + break; data += wr; bytes -= wr; - wr = __vfs_write(file, data, bytes, &file->f_pos); } mutex_unlock(&sbi->pipe_mutex); -- 1.9.1