From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756976Ab3K0A4w (ORCPT ); Tue, 26 Nov 2013 19:56:52 -0500 Received: from mail.linuxfoundation.org ([140.211.169.12]:38779 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756645Ab3K0A4o (ORCPT ); Tue, 26 Nov 2013 19:56:44 -0500 From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Mikulas Patocka , Tejun Heo , Jens Axboe Subject: [PATCH 3.4 31/39] block: fix a probe argument to blk_register_region Date: Tue, 26 Nov 2013 16:56:55 -0800 Message-Id: <20131127005621.229796789@linuxfoundation.org> X-Mailer: git-send-email 1.8.5.rc3 In-Reply-To: <20131127005619.011763867@linuxfoundation.org> References: <20131127005619.011763867@linuxfoundation.org> User-Agent: quilt/0.60-1 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 3.4-stable review patch. If anyone has any objections, please let me know. ------------------ From: Mikulas Patocka commit a207f5937630dd35bd2550620bef416937a1365e upstream. The probe function is supposed to return NULL on failure (as we can see in kobj_lookup: kobj = probe(dev, index, data); ... if (kobj) return kobj; However, in loop and brd, it returns negative error from ERR_PTR. This causes a crash if we simulate disk allocation failure and run less -f /dev/loop0 because the negative number is interpreted as a pointer: BUG: unable to handle kernel NULL pointer dereference at 00000000000002b4 IP: [] __blkdev_get+0x28/0x450 PGD 23c677067 PUD 23d6d1067 PMD 0 Oops: 0000 [#1] PREEMPT SMP Modules linked in: loop hpfs nvidia(PO) ip6table_filter ip6_tables uvesafb cfbcopyarea cfbimgblt cfbfillrect fbcon font bitblit fbcon_rotate fbcon_cw fbcon_ud fbcon_ccw softcursor fb fbdev msr ipt_MASQUERADE iptable_nat nf_nat_ipv4 nf_conntrack_ipv4 nf_defrag_ipv4 xt_state ipt_REJECT xt_tcpudp iptable_filter ip_tables x_tables bridge stp llc tun ipv6 cpufreq_stats cpufreq_ondemand cpufreq_userspace cpufreq_powersave cpufreq_conservative hid_generic spadfs usbhid hid fuse raid0 snd_usb_audio snd_pcm_oss snd_mixer_oss md_mod snd_pcm snd_timer snd_page_alloc snd_hwdep snd_usbmidi_lib dmi_sysfs snd_rawmidi nf_nat_ftp nf_nat nf_conntrack_ftp nf_conntrack snd soundcore lm85 hwmon_vid ohci_hcd ehci_pci ehci_hcd serverworks sata_svw libata acpi_cpufreq freq_table mperf ide_core usbcore kvm_amd kvm tg3 i2c_piix4 libphy microcode e100 usb_common ptp skge i2c_core pcspkr k10temp evdev floppy hwmon pps_core mii rtc_cmos button processor unix [last unloaded: nvidia] CPU: 1 PID: 6831 Comm: less Tainted: P W O 3.10.15-devel #18 Hardware name: empty empty/S3992-E, BIOS 'V1.06 ' 06/09/2009 task: ffff880203cc6bc0 ti: ffff88023e47c000 task.ti: ffff88023e47c000 RIP: 0010:[] [] __blkdev_get+0x28/0x450 RSP: 0018:ffff88023e47dbd8 EFLAGS: 00010286 RAX: ffffffffffffff74 RBX: ffffffffffffff74 RCX: 0000000000000000 RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000001 RBP: ffff88023e47dc18 R08: 0000000000000002 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000000 R12: ffff88023f519658 R13: ffffffff8118c300 R14: 0000000000000000 R15: ffff88023f519640 FS: 00007f2070bf7700(0000) GS:ffff880247400000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00000000000002b4 CR3: 000000023da1d000 CR4: 00000000000007e0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400 Stack: 0000000000000002 0000001d00000000 000000003e47dc50 ffff88023f519640 ffff88043d5bb668 ffffffff8118c300 ffff88023d683550 ffff88023e47de60 ffff88023e47dc98 ffffffff8118c10d 0000001d81605698 0000000000000292 Call Trace: [] ? blkdev_get_by_dev+0x60/0x60 [] blkdev_get+0x1dd/0x370 [] ? blkdev_get_by_dev+0x60/0x60 [] ? _raw_spin_unlock+0x2c/0x50 [] ? blkdev_get_by_dev+0x60/0x60 [] blkdev_open+0x65/0x80 [] do_dentry_open.isra.18+0x23e/0x2f0 [] finish_open+0x34/0x50 [] do_last.isra.62+0x2d2/0xc50 [] path_openat.isra.63+0xb8/0x4d0 [] ? might_fault+0x4e/0xa0 [] do_filp_open+0x40/0x90 [] ? _raw_spin_unlock+0x2c/0x50 [] ? __alloc_fd+0xa5/0x1f0 [] do_sys_open+0xef/0x1d0 [] SyS_open+0x19/0x20 [] system_call_fastpath+0x1a/0x1f Code: 44 00 00 55 48 89 e5 41 57 49 89 ff 41 56 41 89 d6 41 55 41 54 4c 8d 67 18 53 48 83 ec 18 89 75 cc e9 f2 00 00 00 0f 1f 44 00 00 <48> 8b 80 40 03 00 00 48 89 df 4c 8b 68 58 e8 d5 a4 07 00 44 89 RIP [] __blkdev_get+0x28/0x450 RSP CR2: 00000000000002b4 ---[ end trace bb7f32dbf02398dc ]--- The brd change should be backported to stable kernels starting with 2.6.25. The loop change should be backported to stable kernels starting with 2.6.22. Signed-off-by: Mikulas Patocka Acked-by: Tejun Heo Signed-off-by: Jens Axboe Signed-off-by: Greg Kroah-Hartman --- drivers/block/brd.c | 2 +- drivers/block/loop.c | 2 +- 2 files changed, 2 insertions(+), 2 deletions(-) --- a/drivers/block/brd.c +++ b/drivers/block/brd.c @@ -546,7 +546,7 @@ static struct kobject *brd_probe(dev_t d mutex_lock(&brd_devices_mutex); brd = brd_init_one(MINOR(dev) >> part_shift); - kobj = brd ? get_disk(brd->brd_disk) : ERR_PTR(-ENOMEM); + kobj = brd ? get_disk(brd->brd_disk) : NULL; mutex_unlock(&brd_devices_mutex); *part = 0; --- a/drivers/block/loop.c +++ b/drivers/block/loop.c @@ -1743,7 +1743,7 @@ static struct kobject *loop_probe(dev_t if (err < 0) err = loop_add(&lo, MINOR(dev) >> part_shift); if (err < 0) - kobj = ERR_PTR(err); + kobj = NULL; else kobj = get_disk(lo->lo_disk); mutex_unlock(&loop_index_mutex);