From: Sasha Levin <sashal@kernel.org> To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Stefan Hajnoczi <stefanha@redhat.com>, Lance Digby <ldigby@redhat.com>, "Michael S . Tsirkin" <mst@redhat.com>, Stefano Garzarella <sgarzare@redhat.com>, Sasha Levin <sashal@kernel.org>, virtualization@lists.linux-foundation.org, linux-block@vger.kernel.org Subject: [PATCH AUTOSEL 4.19 22/31] virtio-blk: handle block_device_operations callbacks after hot unplug Date: Thu, 14 May 2020 14:54:04 -0400 [thread overview] Message-ID: <20200514185413.20755-22-sashal@kernel.org> (raw) In-Reply-To: <20200514185413.20755-1-sashal@kernel.org> From: Stefan Hajnoczi <stefanha@redhat.com> [ Upstream commit 90b5feb8c4bebc76c27fcaf3e1a0e5ca2d319e9e ] A userspace process holding a file descriptor to a virtio_blk device can still invoke block_device_operations after hot unplug. This leads to a use-after-free accessing vblk->vdev in virtblk_getgeo() when ioctl(HDIO_GETGEO) is invoked: BUG: unable to handle kernel NULL pointer dereference at 0000000000000090 IP: [<ffffffffc00e5450>] virtio_check_driver_offered_feature+0x10/0x90 [virtio] PGD 800000003a92f067 PUD 3a930067 PMD 0 Oops: 0000 [#1] SMP CPU: 0 PID: 1310 Comm: hdio-getgeo Tainted: G OE ------------ 3.10.0-1062.el7.x86_64 #1 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.13.0-0-gf21b5a4aeb02-prebuilt.qemu.org 04/01/2014 task: ffff9be5fbfb8000 ti: ffff9be5fa890000 task.ti: ffff9be5fa890000 RIP: 0010:[<ffffffffc00e5450>] [<ffffffffc00e5450>] virtio_check_driver_offered_feature+0x10/0x90 [virtio] RSP: 0018:ffff9be5fa893dc8 EFLAGS: 00010246 RAX: ffff9be5fc3f3400 RBX: ffff9be5fa893e30 RCX: 0000000000000000 RDX: 0000000000000000 RSI: 0000000000000004 RDI: ffff9be5fbc10b40 RBP: ffff9be5fa893dc8 R08: 0000000000000301 R09: 0000000000000301 R10: 0000000000000000 R11: 0000000000000000 R12: ffff9be5fdc24680 R13: ffff9be5fbc10b40 R14: ffff9be5fbc10480 R15: 0000000000000000 FS: 00007f1bfb968740(0000) GS:ffff9be5ffc00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000000000000090 CR3: 000000003a894000 CR4: 0000000000360ff0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: [<ffffffffc016ac37>] virtblk_getgeo+0x47/0x110 [virtio_blk] [<ffffffff8d3f200d>] ? handle_mm_fault+0x39d/0x9b0 [<ffffffff8d561265>] blkdev_ioctl+0x1f5/0xa20 [<ffffffff8d488771>] block_ioctl+0x41/0x50 [<ffffffff8d45d9e0>] do_vfs_ioctl+0x3a0/0x5a0 [<ffffffff8d45dc81>] SyS_ioctl+0xa1/0xc0 A related problem is that virtblk_remove() leaks the vd_index_ida index when something still holds a reference to vblk->disk during hot unplug. This causes virtio-blk device names to be lost (vda, vdb, etc). Fix these issues by protecting vblk->vdev with a mutex and reference counting vblk so the vd_index_ida index can be removed in all cases. Fixes: 48e4043d4529 ("virtio: add virtio disk geometry feature") Reported-by: Lance Digby <ldigby@redhat.com> Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com> Link: https://lore.kernel.org/r/20200430140442.171016-1-stefanha@redhat.com Signed-off-by: Michael S. Tsirkin <mst@redhat.com> Reviewed-by: Stefano Garzarella <sgarzare@redhat.com> Signed-off-by: Sasha Levin <sashal@kernel.org> --- drivers/block/virtio_blk.c | 86 ++++++++++++++++++++++++++++++++++---- 1 file changed, 78 insertions(+), 8 deletions(-) diff --git a/drivers/block/virtio_blk.c b/drivers/block/virtio_blk.c index 9a3c2b14ac378..9be54e5ef96ae 100644 --- a/drivers/block/virtio_blk.c +++ b/drivers/block/virtio_blk.c @@ -31,6 +31,15 @@ struct virtio_blk_vq { } ____cacheline_aligned_in_smp; struct virtio_blk { + /* + * This mutex must be held by anything that may run after + * virtblk_remove() sets vblk->vdev to NULL. + * + * blk-mq, virtqueue processing, and sysfs attribute code paths are + * shut down before vblk->vdev is set to NULL and therefore do not need + * to hold this mutex. + */ + struct mutex vdev_mutex; struct virtio_device *vdev; /* The disk structure for the kernel. */ @@ -42,6 +51,13 @@ struct virtio_blk { /* Process context for config space updates */ struct work_struct config_work; + /* + * Tracks references from block_device_operations open/release and + * virtio_driver probe/remove so this object can be freed once no + * longer in use. + */ + refcount_t refs; + /* What host tells us, plus 2 for header & tailer. */ unsigned int sg_elems; @@ -320,10 +336,55 @@ static int virtblk_get_id(struct gendisk *disk, char *id_str) return err; } +static void virtblk_get(struct virtio_blk *vblk) +{ + refcount_inc(&vblk->refs); +} + +static void virtblk_put(struct virtio_blk *vblk) +{ + if (refcount_dec_and_test(&vblk->refs)) { + ida_simple_remove(&vd_index_ida, vblk->index); + mutex_destroy(&vblk->vdev_mutex); + kfree(vblk); + } +} + +static int virtblk_open(struct block_device *bd, fmode_t mode) +{ + struct virtio_blk *vblk = bd->bd_disk->private_data; + int ret = 0; + + mutex_lock(&vblk->vdev_mutex); + + if (vblk->vdev) + virtblk_get(vblk); + else + ret = -ENXIO; + + mutex_unlock(&vblk->vdev_mutex); + return ret; +} + +static void virtblk_release(struct gendisk *disk, fmode_t mode) +{ + struct virtio_blk *vblk = disk->private_data; + + virtblk_put(vblk); +} + /* We provide getgeo only to please some old bootloader/partitioning tools */ static int virtblk_getgeo(struct block_device *bd, struct hd_geometry *geo) { struct virtio_blk *vblk = bd->bd_disk->private_data; + int ret = 0; + + mutex_lock(&vblk->vdev_mutex); + + if (!vblk->vdev) { + ret = -ENXIO; + goto out; + } /* see if the host passed in geometry config */ if (virtio_has_feature(vblk->vdev, VIRTIO_BLK_F_GEOMETRY)) { @@ -339,12 +400,16 @@ static int virtblk_getgeo(struct block_device *bd, struct hd_geometry *geo) geo->sectors = 1 << 5; geo->cylinders = get_capacity(bd->bd_disk) >> 11; } - return 0; +out: + mutex_unlock(&vblk->vdev_mutex); + return ret; } static const struct block_device_operations virtblk_fops = { .ioctl = virtblk_ioctl, .owner = THIS_MODULE, + .open = virtblk_open, + .release = virtblk_release, .getgeo = virtblk_getgeo, }; @@ -672,6 +737,10 @@ static int virtblk_probe(struct virtio_device *vdev) goto out_free_index; } + /* This reference is dropped in virtblk_remove(). */ + refcount_set(&vblk->refs, 1); + mutex_init(&vblk->vdev_mutex); + vblk->vdev = vdev; vblk->sg_elems = sg_elems; @@ -824,8 +893,6 @@ static int virtblk_probe(struct virtio_device *vdev) static void virtblk_remove(struct virtio_device *vdev) { struct virtio_blk *vblk = vdev->priv; - int index = vblk->index; - int refc; /* Make sure no work handler is accessing the device. */ flush_work(&vblk->config_work); @@ -835,18 +902,21 @@ static void virtblk_remove(struct virtio_device *vdev) blk_mq_free_tag_set(&vblk->tag_set); + mutex_lock(&vblk->vdev_mutex); + /* Stop all the virtqueues. */ vdev->config->reset(vdev); - refc = kref_read(&disk_to_dev(vblk->disk)->kobj.kref); + /* Virtqueues are stopped, nothing can use vblk->vdev anymore. */ + vblk->vdev = NULL; + put_disk(vblk->disk); vdev->config->del_vqs(vdev); kfree(vblk->vqs); - kfree(vblk); - /* Only free device id if we don't have any users */ - if (refc == 1) - ida_simple_remove(&vd_index_ida, index); + mutex_unlock(&vblk->vdev_mutex); + + virtblk_put(vblk); } #ifdef CONFIG_PM_SLEEP -- 2.20.1
WARNING: multiple messages have this Message-ID (diff)
From: Sasha Levin <sashal@kernel.org> To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Sasha Levin <sashal@kernel.org>, "Michael S . Tsirkin" <mst@redhat.com>, Lance Digby <ldigby@redhat.com>, virtualization@lists.linux-foundation.org, linux-block@vger.kernel.org, Stefan Hajnoczi <stefanha@redhat.com> Subject: [PATCH AUTOSEL 4.19 22/31] virtio-blk: handle block_device_operations callbacks after hot unplug Date: Thu, 14 May 2020 14:54:04 -0400 [thread overview] Message-ID: <20200514185413.20755-22-sashal@kernel.org> (raw) In-Reply-To: <20200514185413.20755-1-sashal@kernel.org> From: Stefan Hajnoczi <stefanha@redhat.com> [ Upstream commit 90b5feb8c4bebc76c27fcaf3e1a0e5ca2d319e9e ] A userspace process holding a file descriptor to a virtio_blk device can still invoke block_device_operations after hot unplug. This leads to a use-after-free accessing vblk->vdev in virtblk_getgeo() when ioctl(HDIO_GETGEO) is invoked: BUG: unable to handle kernel NULL pointer dereference at 0000000000000090 IP: [<ffffffffc00e5450>] virtio_check_driver_offered_feature+0x10/0x90 [virtio] PGD 800000003a92f067 PUD 3a930067 PMD 0 Oops: 0000 [#1] SMP CPU: 0 PID: 1310 Comm: hdio-getgeo Tainted: G OE ------------ 3.10.0-1062.el7.x86_64 #1 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.13.0-0-gf21b5a4aeb02-prebuilt.qemu.org 04/01/2014 task: ffff9be5fbfb8000 ti: ffff9be5fa890000 task.ti: ffff9be5fa890000 RIP: 0010:[<ffffffffc00e5450>] [<ffffffffc00e5450>] virtio_check_driver_offered_feature+0x10/0x90 [virtio] RSP: 0018:ffff9be5fa893dc8 EFLAGS: 00010246 RAX: ffff9be5fc3f3400 RBX: ffff9be5fa893e30 RCX: 0000000000000000 RDX: 0000000000000000 RSI: 0000000000000004 RDI: ffff9be5fbc10b40 RBP: ffff9be5fa893dc8 R08: 0000000000000301 R09: 0000000000000301 R10: 0000000000000000 R11: 0000000000000000 R12: ffff9be5fdc24680 R13: ffff9be5fbc10b40 R14: ffff9be5fbc10480 R15: 0000000000000000 FS: 00007f1bfb968740(0000) GS:ffff9be5ffc00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000000000000090 CR3: 000000003a894000 CR4: 0000000000360ff0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: [<ffffffffc016ac37>] virtblk_getgeo+0x47/0x110 [virtio_blk] [<ffffffff8d3f200d>] ? handle_mm_fault+0x39d/0x9b0 [<ffffffff8d561265>] blkdev_ioctl+0x1f5/0xa20 [<ffffffff8d488771>] block_ioctl+0x41/0x50 [<ffffffff8d45d9e0>] do_vfs_ioctl+0x3a0/0x5a0 [<ffffffff8d45dc81>] SyS_ioctl+0xa1/0xc0 A related problem is that virtblk_remove() leaks the vd_index_ida index when something still holds a reference to vblk->disk during hot unplug. This causes virtio-blk device names to be lost (vda, vdb, etc). Fix these issues by protecting vblk->vdev with a mutex and reference counting vblk so the vd_index_ida index can be removed in all cases. Fixes: 48e4043d4529 ("virtio: add virtio disk geometry feature") Reported-by: Lance Digby <ldigby@redhat.com> Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com> Link: https://lore.kernel.org/r/20200430140442.171016-1-stefanha@redhat.com Signed-off-by: Michael S. Tsirkin <mst@redhat.com> Reviewed-by: Stefano Garzarella <sgarzare@redhat.com> Signed-off-by: Sasha Levin <sashal@kernel.org> --- drivers/block/virtio_blk.c | 86 ++++++++++++++++++++++++++++++++++---- 1 file changed, 78 insertions(+), 8 deletions(-) diff --git a/drivers/block/virtio_blk.c b/drivers/block/virtio_blk.c index 9a3c2b14ac378..9be54e5ef96ae 100644 --- a/drivers/block/virtio_blk.c +++ b/drivers/block/virtio_blk.c @@ -31,6 +31,15 @@ struct virtio_blk_vq { } ____cacheline_aligned_in_smp; struct virtio_blk { + /* + * This mutex must be held by anything that may run after + * virtblk_remove() sets vblk->vdev to NULL. + * + * blk-mq, virtqueue processing, and sysfs attribute code paths are + * shut down before vblk->vdev is set to NULL and therefore do not need + * to hold this mutex. + */ + struct mutex vdev_mutex; struct virtio_device *vdev; /* The disk structure for the kernel. */ @@ -42,6 +51,13 @@ struct virtio_blk { /* Process context for config space updates */ struct work_struct config_work; + /* + * Tracks references from block_device_operations open/release and + * virtio_driver probe/remove so this object can be freed once no + * longer in use. + */ + refcount_t refs; + /* What host tells us, plus 2 for header & tailer. */ unsigned int sg_elems; @@ -320,10 +336,55 @@ static int virtblk_get_id(struct gendisk *disk, char *id_str) return err; } +static void virtblk_get(struct virtio_blk *vblk) +{ + refcount_inc(&vblk->refs); +} + +static void virtblk_put(struct virtio_blk *vblk) +{ + if (refcount_dec_and_test(&vblk->refs)) { + ida_simple_remove(&vd_index_ida, vblk->index); + mutex_destroy(&vblk->vdev_mutex); + kfree(vblk); + } +} + +static int virtblk_open(struct block_device *bd, fmode_t mode) +{ + struct virtio_blk *vblk = bd->bd_disk->private_data; + int ret = 0; + + mutex_lock(&vblk->vdev_mutex); + + if (vblk->vdev) + virtblk_get(vblk); + else + ret = -ENXIO; + + mutex_unlock(&vblk->vdev_mutex); + return ret; +} + +static void virtblk_release(struct gendisk *disk, fmode_t mode) +{ + struct virtio_blk *vblk = disk->private_data; + + virtblk_put(vblk); +} + /* We provide getgeo only to please some old bootloader/partitioning tools */ static int virtblk_getgeo(struct block_device *bd, struct hd_geometry *geo) { struct virtio_blk *vblk = bd->bd_disk->private_data; + int ret = 0; + + mutex_lock(&vblk->vdev_mutex); + + if (!vblk->vdev) { + ret = -ENXIO; + goto out; + } /* see if the host passed in geometry config */ if (virtio_has_feature(vblk->vdev, VIRTIO_BLK_F_GEOMETRY)) { @@ -339,12 +400,16 @@ static int virtblk_getgeo(struct block_device *bd, struct hd_geometry *geo) geo->sectors = 1 << 5; geo->cylinders = get_capacity(bd->bd_disk) >> 11; } - return 0; +out: + mutex_unlock(&vblk->vdev_mutex); + return ret; } static const struct block_device_operations virtblk_fops = { .ioctl = virtblk_ioctl, .owner = THIS_MODULE, + .open = virtblk_open, + .release = virtblk_release, .getgeo = virtblk_getgeo, }; @@ -672,6 +737,10 @@ static int virtblk_probe(struct virtio_device *vdev) goto out_free_index; } + /* This reference is dropped in virtblk_remove(). */ + refcount_set(&vblk->refs, 1); + mutex_init(&vblk->vdev_mutex); + vblk->vdev = vdev; vblk->sg_elems = sg_elems; @@ -824,8 +893,6 @@ static int virtblk_probe(struct virtio_device *vdev) static void virtblk_remove(struct virtio_device *vdev) { struct virtio_blk *vblk = vdev->priv; - int index = vblk->index; - int refc; /* Make sure no work handler is accessing the device. */ flush_work(&vblk->config_work); @@ -835,18 +902,21 @@ static void virtblk_remove(struct virtio_device *vdev) blk_mq_free_tag_set(&vblk->tag_set); + mutex_lock(&vblk->vdev_mutex); + /* Stop all the virtqueues. */ vdev->config->reset(vdev); - refc = kref_read(&disk_to_dev(vblk->disk)->kobj.kref); + /* Virtqueues are stopped, nothing can use vblk->vdev anymore. */ + vblk->vdev = NULL; + put_disk(vblk->disk); vdev->config->del_vqs(vdev); kfree(vblk->vqs); - kfree(vblk); - /* Only free device id if we don't have any users */ - if (refc == 1) - ida_simple_remove(&vd_index_ida, index); + mutex_unlock(&vblk->vdev_mutex); + + virtblk_put(vblk); } #ifdef CONFIG_PM_SLEEP -- 2.20.1
next prev parent reply other threads:[~2020-05-14 19:03 UTC|newest] Thread overview: 37+ messages / expand[flat|nested] mbox.gz Atom feed top 2020-05-14 18:53 [PATCH AUTOSEL 4.19 01/31] Makefile: disallow data races on gcc-10 as well Sasha Levin 2020-05-14 18:53 ` [PATCH AUTOSEL 4.19 02/31] gcc-common.h: Update for GCC 10 Sasha Levin 2020-05-14 18:53 ` [PATCH AUTOSEL 4.19 03/31] HID: multitouch: add eGalaxTouch P80H84 support Sasha Levin 2020-05-14 18:53 ` [PATCH AUTOSEL 4.19 04/31] HID: alps: Add AUI1657 device ID Sasha Levin 2020-05-14 18:53 ` [PATCH AUTOSEL 4.19 05/31] HID: alps: ALPS_1657 is too specific; use U1_UNICORN_LEGACY instead Sasha Levin 2020-05-14 18:53 ` [PATCH AUTOSEL 4.19 06/31] phy: tegra: Select USB_COMMON for usb_get_maximum_speed() Sasha Levin 2020-05-14 18:53 ` [PATCH AUTOSEL 4.19 07/31] scsi: qla2xxx: Fix hang when issuing nvme disconnect-all in NPIV Sasha Levin 2020-05-14 18:53 ` [PATCH AUTOSEL 4.19 08/31] scsi: qla2xxx: Delete all sessions before unregister local nvme port Sasha Levin 2020-05-14 18:53 ` [PATCH AUTOSEL 4.19 09/31] configfs: fix config_item refcnt leak in configfs_rmdir() Sasha Levin 2020-05-14 18:53 ` [PATCH AUTOSEL 4.19 10/31] vhost/vsock: fix packet delivery order to monitoring devices Sasha Levin 2020-05-14 18:53 ` Sasha Levin 2020-05-14 18:53 ` [PATCH AUTOSEL 4.19 11/31] aquantia: Fix the media type of AQC100 ethernet controller in the driver Sasha Levin 2020-05-14 18:53 ` [PATCH AUTOSEL 4.19 12/31] net/sonic: Fix a resource leak in an error handling path in 'jazz_sonic_probe()' Sasha Levin 2020-05-14 18:53 ` [PATCH AUTOSEL 4.19 13/31] most: core: use function subsys_initcall() Sasha Levin 2020-05-14 18:53 ` Sasha Levin 2020-05-14 18:53 ` [PATCH AUTOSEL 4.19 14/31] component: Silence bind error on -EPROBE_DEFER Sasha Levin 2020-05-14 18:53 ` [PATCH AUTOSEL 4.19 15/31] scsi: ibmvscsi: Fix WARN_ON during event pool release Sasha Levin 2020-05-14 18:53 ` Sasha Levin 2020-05-14 18:53 ` [PATCH AUTOSEL 4.19 16/31] HID: i2c-hid: reset Synaptics SYNA2393 on resume Sasha Levin 2020-05-14 18:53 ` [PATCH AUTOSEL 4.19 17/31] soc: qcom: ipa: IPA endpoints Sasha Levin 2020-05-14 18:54 ` [PATCH AUTOSEL 4.19 18/31] net: ipa: fix a bug in ipa_endpoint_stop() Sasha Levin 2020-05-14 18:54 ` [PATCH AUTOSEL 4.19 19/31] net: moxa: Fix a potential double 'free_irq()' Sasha Levin 2020-05-14 18:54 ` [PATCH AUTOSEL 4.19 20/31] x86/apic: Move TSC deadline timer debug printk Sasha Levin 2020-05-14 18:54 ` [PATCH AUTOSEL 4.19 21/31] gtp: set NLM_F_MULTI flag in gtp_genl_dump_pdp() Sasha Levin 2020-05-14 18:54 ` Sasha Levin [this message] 2020-05-14 18:54 ` [PATCH AUTOSEL 4.19 22/31] virtio-blk: handle block_device_operations callbacks after hot unplug Sasha Levin 2020-05-14 18:54 ` [PATCH AUTOSEL 4.19 23/31] HID: quirks: Add HID_QUIRK_NO_INIT_REPORTS quirk for Dell K12A keyboard-dock Sasha Levin 2020-05-14 18:54 ` [PATCH AUTOSEL 4.19 24/31] ceph: fix double unlock in handle_cap_export() Sasha Levin 2020-05-14 18:54 ` [PATCH AUTOSEL 4.19 25/31] stmmac: fix pointer check after utilization in stmmac_interrupt Sasha Levin 2020-05-14 18:54 ` Sasha Levin 2020-05-14 18:54 ` [PATCH AUTOSEL 4.19 26/31] USB: core: Fix misleading driver bug report Sasha Levin 2020-05-14 18:54 ` [PATCH AUTOSEL 4.19 27/31] platform/x86: asus-nb-wmi: Do not load on Asus T100TA and T200TA Sasha Levin 2020-05-14 18:54 ` [PATCH AUTOSEL 4.19 28/31] ARM: futex: Address build warning Sasha Levin 2020-05-14 18:54 ` Sasha Levin 2020-05-14 18:54 ` [PATCH AUTOSEL 4.19 29/31] crypto: lrw - simplify error handling in create() Sasha Levin 2020-05-14 18:54 ` [PATCH AUTOSEL 4.19 30/31] crypto: xts - simplify error handling in ->create() Sasha Levin 2020-05-14 18:54 ` [PATCH AUTOSEL 4.19 31/31] gcc-10: avoid shadowing standard library 'free()' in crypto Sasha Levin
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