From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx122.postini.com [74.125.245.122]) by kanga.kvack.org (Postfix) with SMTP id EE5F46B0002 for ; Mon, 18 Feb 2013 19:35:23 -0500 (EST) Date: Tue, 19 Feb 2013 00:35:22 +0000 From: Christoph Lameter Subject: Re: slab: odd BUG on kzalloc In-Reply-To: <5120FDA4.2060704@oracle.com> Message-ID: <0000013cefe056e0-daedd018-43cd-472f-9b20-27b2a897ae2a-000000@email.amazonses.com> References: <5120FDA4.2060704@oracle.com> MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: owner-linux-mm@kvack.org List-ID: To: Sasha Levin Cc: Pekka Enberg , mpm@selenic.com, linux-mm , "linux-kernel@vger.kernel.org" , Dave Jones Maybe the result of free pointer corruption due to writing to an object after free. Please run again with slub_debug specified on the commandline to get detailed reports on how this came about. On Sun, 17 Feb 2013, Sasha Levin wrote: > Hi all, > > I was fuzzing with trinity inside a KVM tools guest, running latest -next kernel, > and hit the following bug: > > [ 169.773688] BUG: unable to handle kernel NULL pointer dereference at 0000000000000001 > [ 169.774976] IP: [] memset+0x1f/0xb0 > [ 169.775989] PGD 93e02067 PUD ac1a2067 PMD 0 > [ 169.776898] Oops: 0002 [#1] PREEMPT SMP DEBUG_PAGEALLOC > [ 169.777923] Dumping ftrace buffer: > [ 169.778595] (ftrace buffer empty) > [ 169.779352] Modules linked in: > [ 169.779996] CPU 0 > [ 169.780031] Pid: 13438, comm: trinity Tainted: G W 3.8.0-rc7-next-20130215-sasha-00003-gea816fa #286 > [ 169.780031] RIP: 0010:[] [] memset+0x1f/0xb0 > [ 169.780031] RSP: 0018:ffff8800aef19e00 EFLAGS: 00010206 > [ 169.780031] RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000000000080 > [ 169.780031] RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000001 > [ 169.780031] RBP: ffff8800aef19e68 R08: 0000000000000000 R09: 0000000000000001 > [ 169.780031] R10: 0000000000000001 R11: 0000000000000000 R12: ffff8800bb001b00 > [ 169.780031] R13: ffff8800bb001b00 R14: 0000000000000001 R15: 0000000000537000 > [ 169.780031] FS: 00007fb73581b700(0000) GS:ffff8800bb600000(0000) knlGS:0000000000000000 > [ 169.780031] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 > [ 169.780031] CR2: 0000000000000001 CR3: 00000000aed31000 CR4: 00000000000406f0 > [ 169.780031] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 > [ 169.780031] DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400 > [ 169.780031] Process trinity (pid: 13438, threadinfo ffff8800aef18000, task ffff8800aed7b000) > [ 169.780031] Stack: > [ 169.780031] ffffffff81269586 ffff8800aef19e38 0000000000000280 ffffffff81291a2e > [ 169.780031] 000080d0aa39d9e8 ffff8800aef19e48 0000000000000000 ffff8800aa39d9e8 > [ 169.780031] ffff8800a65cc780 ffff8800aa39d960 00000000ffffffea 0000000000000000 > [ 169.780031] Call Trace: > [ 169.780031] [] ? kmem_cache_alloc_trace+0x176/0x330 > [ 169.780031] [] ? alloc_pipe_info+0x3e/0xa0 > [ 169.780031] [] alloc_pipe_info+0x3e/0xa0 > [ 169.780031] [] get_pipe_inode+0x36/0xe0 > [ 169.780031] [] create_pipe_files+0x23/0x140 > [ 169.780031] [] __do_pipe_flags+0x3d/0xe0 > [ 169.780031] [] sys_pipe2+0x1b/0xa0 > [ 169.780031] [] ? tracesys+0x7e/0xe6 > [ 169.780031] [] sys_pipe+0xb/0x10 > [ 169.780031] [] tracesys+0xe1/0xe6 > [ 169.780031] Code: 1e 44 88 1f c3 90 90 90 90 90 90 90 49 89 f9 48 89 d1 83 e2 07 48 c1 e9 03 40 0f b6 f6 48 b8 01 01 01 01 01 > 01 01 01 48 0f af c6 48 ab 89 d1 f3 aa 4c 89 c8 c3 66 66 66 90 66 66 66 90 66 66 > [ 169.780031] RIP [] memset+0x1f/0xb0 > [ 169.780031] RSP > [ 169.780031] CR2: 0000000000000001 > [ 169.930103] ---[ end trace 4d135f3def21b4bd ]--- > > The code translates to the following in fs/pipe.c:alloc_pipe_info : > > pipe = kzalloc(sizeof(struct pipe_inode_info), GFP_KERNEL); > if (pipe) { > pipe->bufs = kzalloc(sizeof(struct pipe_buffer) * PIPE_DEF_BUFFERS, GFP_KERNEL); <=== this > if (pipe->bufs) { > init_waitqueue_head(&pipe->wait); > > > Thanks, > Sasha > -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org