From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx153.postini.com [74.125.245.153]) by kanga.kvack.org (Postfix) with SMTP id 3E02F6B0069 for ; Thu, 18 Oct 2012 18:47:02 -0400 (EDT) Message-ID: <508086DA.3010600@oracle.com> Date: Thu, 18 Oct 2012 18:46:50 -0400 From: Sasha Levin MIME-Version: 1.0 Subject: mm: NULL ptr deref in anon_vma_interval_tree_verify Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: Michel Lespinasse , hughd@google.com, Andrew Morton Cc: linux-mm , "linux-kernel@vger.kernel.org" , Dave Jones Hi all, While fuzzing with trinity inside a KVM tools (lkvm) guest, on today's linux-next kernel, I saw the following: [ 1857.278176] BUG: unable to handle kernel NULL pointer dereference at 0000000000000090 [ 1857.283725] IP: [] anon_vma_interval_tree_verify+0xf/0xa0 [ 1857.283725] PGD 6e19e067 PUD 6e19f067 PMD 0 [ 1857.283725] Oops: 0000 [#1] PREEMPT SMP DEBUG_PAGEALLOC [ 1857.283725] Dumping ftrace buffer: [ 1857.283725] (ftrace buffer empty) [ 1857.283725] CPU 2 [ 1857.283725] Pid: 15637, comm: trinity-child18 Tainted: G W 3.7.0-rc1-next-20121018-sasha-00002-g60a870d-dirty #61 [ 1857.283725] RIP: 0010:[] [] anon_vma_interval_tree_verify+0xf/0xa0 [ 1857.283725] RSP: 0018:ffff88007df0fce8 EFLAGS: 00010296 [ 1857.283725] RAX: ffff880089db1000 RBX: ffff880089db0ff0 RCX: ffff8800869e6928 [ 1857.283725] RDX: 0000000000000000 RSI: ffff880089db1008 RDI: ffff880089db0ff0 [ 1857.283725] RBP: ffff88007df0fcf8 R08: ffff88006427d508 R09: ffff88012bb95f20 [ 1857.283725] R10: 0000000000000001 R11: ffff8800c8525c60 R12: ffff88006e199370 [ 1857.283725] R13: ffff88006e199300 R14: 0000000000000000 R15: ffff880089db1000 [ 1857.283725] FS: 00007f322fd4c700(0000) GS:ffff88004d600000(0000) knlGS:0000000000000000 [ 1857.283725] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 1857.283725] CR2: 0000000000000090 CR3: 000000006e19d000 CR4: 00000000000406e0 [ 1857.283725] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 [ 1857.283725] DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400 [ 1857.283725] Process trinity-child18 (pid: 15637, threadinfo ffff88007df0e000, task ffff88007ac80000) [ 1857.283725] Stack: [ 1857.283725] ffff88007df0fd38 ffff880089db0ff0 ffff88007df0fd48 ffffffff81233b58 [ 1857.283725] ffff88007df0fd38 ffff880089db1000 00000000000080d0 ffff880089db1000 [ 1857.283725] ffff88012bb95f20 ffff8800005d97c8 ffff8800005d97d8 ffff880089db1000 [ 1857.283725] Call Trace: [ 1857.283725] [] validate_mm+0x58/0x1e0 [ 1857.283725] [] vma_link+0x94/0xe0 [ 1857.283725] [] ? _raw_spin_unlock_irqrestore+0x84/0xb0 [ 1857.283725] [] mmap_region+0x3f5/0x5c0 [ 1857.283725] [] do_mmap_pgoff+0x2b7/0x330 [ 1857.283725] [] ? vm_mmap_pgoff+0x61/0xa0 [ 1857.283725] [] vm_mmap_pgoff+0x7a/0xa0 [ 1857.283725] [] sys_mmap_pgoff+0x182/0x1a0 [ 1857.283725] [] ? syscall_trace_enter+0x20/0x2e0 [ 1857.283725] [] sys_mmap+0x1d/0x20 [ 1857.283725] [] tracesys+0xe1/0xe6 [ 1857.283725] Code: 48 39 ce 77 9e f3 c3 0f 1f 44 00 00 31 c0 c3 66 66 66 66 2e 0f 1f 84 00 00 00 00 00 55 48 89 e5 53 48 89 fb 48 83 ec 08 48 8b 17 <48> 8b 8a 90 00 00 00 48 39 4f 40 74 34 80 3d a6 82 5b 04 00 75 [ 1857.283725] RIP [] anon_vma_interval_tree_verify+0xf/0xa0 [ 1857.283725] RSP [ 1857.283725] CR2: 0000000000000090 [ 1858.611277] ---[ end trace b51cc425e9b07fc0 ]--- The obvious part is that anon_vma_interval_tree_verify() got called with node == NULL, but when looking at the caller: list_for_each_entry(avc, &vma->anon_vma_chain, same_vma) anon_vma_interval_tree_verify(avc); How it got called with said NULL becomes less obvious. 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