Messages in this thread | | | Subject | Re: [PATCH v2 add prerequisite-patch-id] btrfs: fix devid 0 without a replace item by failing the mount | From | Anand Jain <> | Date | Mon, 12 Oct 2020 13:36:27 +0800 |
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Accidentally this patch went to the stable. Pls, ignore. Sorry for the noise. Thanks.
On 12/10/20 1:26 pm, Anand Jain wrote: > If there is a BTRFS_DEV_REPLACE_DEVID without a replace item, then > it means some device is trying to attack or may be corrupted. Fail the > mount so that the user can remove the attacking or fix the corrupted > device. > > As of now if BTRFS_DEV_REPLACE_DEVID is present without the replace > item, in __btrfs_free_extra_devids() we determine that there is an > extra device, and free those extra devices but continue to mount the > device. > However, we were wrong in keeping tack of the rw_devices so the syzbot > testcase failed as below [1]. > > [1] > WARNING: CPU: 1 PID: 3612 at fs/btrfs/volumes.c:1166 close_fs_devices.part.0+0x607/0x800 fs/btrfs/volumes.c:1166 > Kernel panic - not syncing: panic_on_warn set ... > CPU: 1 PID: 3612 Comm: syz-executor.2 Not tainted 5.9.0-rc4-syzkaller #0 > Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 > Call Trace: > __dump_stack lib/dump_stack.c:77 [inline] > dump_stack+0x198/0x1fd lib/dump_stack.c:118 > panic+0x347/0x7c0 kernel/panic.c:231 > __warn.cold+0x20/0x46 kernel/panic.c:600 > report_bug+0x1bd/0x210 lib/bug.c:198 > handle_bug+0x38/0x90 arch/x86/kernel/traps.c:234 > exc_invalid_op+0x14/0x40 arch/x86/kernel/traps.c:254 > asm_exc_invalid_op+0x12/0x20 arch/x86/include/asm/idtentry.h:536 > RIP: 0010:close_fs_devices.part.0+0x607/0x800 fs/btrfs/volumes.c:1166 > Code: 0f b6 04 02 84 c0 74 02 7e 33 48 8b 44 24 18 c6 80 30 01 00 00 00 48 83 c4 30 5b 5d 41 5c 41 5d 41 5e 41 5f c3 e8 99 ce 6a fe <0f> 0b e9 71 ff ff ff e8 8d ce 6a fe 0f 0b e9 20 ff ff ff e8 d1 d5 > RSP: 0018:ffffc900091777e0 EFLAGS: 00010246 > RAX: 0000000000040000 RBX: ffffffffffffffff RCX: ffffc9000c8b7000 > RDX: 0000000000040000 RSI: ffffffff83097f47 RDI: 0000000000000007 > RBP: dffffc0000000000 R08: 0000000000000001 R09: ffff8880988a187f > R10: 0000000000000000 R11: 0000000000000001 R12: ffff88809593a130 > R13: ffff88809593a1ec R14: ffff8880988a1908 R15: ffff88809593a050 > close_fs_devices fs/btrfs/volumes.c:1193 [inline] > btrfs_close_devices+0x95/0x1f0 fs/btrfs/volumes.c:1179 > open_ctree+0x4984/0x4a2d fs/btrfs/disk-io.c:3434 > btrfs_fill_super fs/btrfs/super.c:1316 [inline] > btrfs_mount_root.cold+0x14/0x165 fs/btrfs/super.c:1672 > > The fix here is, when we determine that there isn't a replace item > then fail the mount if there is a replace target device (devid 0). > > Reported-by: syzbot+4cfe71a4da060be47502@syzkaller.appspotmail.com > Signed-off-by: Anand Jain <anand.jain@oracle.com> > --- > Depends on the patches > btrfs: drop never met condition of disk_total_bytes == 0 > btrfs: fix btrfs_find_device unused arg seed > If these patches aren't integrated yet, then please add the last arg in > the function btrfs_find_device(). Any value is fine as it doesn't care. > > fstest case will follow. > > v2: changed title > old: btrfs: fix rw_devices count in __btrfs_free_extra_devids > > In btrfs_init_dev_replace() try to match the presence of replace_item > to the BTRFS_DEV_REPLACE_DEVID device. If fails then fail the > mount. So drop the similar check in __btrfs_free_extra_devids(). > > fs/btrfs/dev-replace.c | 26 ++++++++++++++++++++++++-- > fs/btrfs/volumes.c | 26 +++++++------------------- > 2 files changed, 31 insertions(+), 21 deletions(-) > > diff --git a/fs/btrfs/dev-replace.c b/fs/btrfs/dev-replace.c > index 9340d03661cd..e2b7ae386224 100644 > --- a/fs/btrfs/dev-replace.c > +++ b/fs/btrfs/dev-replace.c > @@ -91,6 +91,17 @@ int btrfs_init_dev_replace(struct btrfs_fs_info *fs_info) > ret = btrfs_search_slot(NULL, dev_root, &key, path, 0, 0); > if (ret) { > no_valid_dev_replace_entry_found: > + /* > + * We don't have a replace item or it's corrupted. > + * If there is a replace target, fail the mount. > + */ > + if (btrfs_find_device(fs_info->fs_devices, > + BTRFS_DEV_REPLACE_DEVID, NULL, NULL)) { > + btrfs_err(fs_info, > + "found replace target device without a replace item"); > + ret = -EIO; > + goto out; > + } > ret = 0; > dev_replace->replace_state = > BTRFS_IOCTL_DEV_REPLACE_STATE_NEVER_STARTED; > @@ -143,8 +154,19 @@ int btrfs_init_dev_replace(struct btrfs_fs_info *fs_info) > case BTRFS_IOCTL_DEV_REPLACE_STATE_NEVER_STARTED: > case BTRFS_IOCTL_DEV_REPLACE_STATE_FINISHED: > case BTRFS_IOCTL_DEV_REPLACE_STATE_CANCELED: > - dev_replace->srcdev = NULL; > - dev_replace->tgtdev = NULL; > + /* > + * We don't have an active replace item but if there is a > + * replace target, fail the mount. > + */ > + if (btrfs_find_device(fs_info->fs_devices, > + BTRFS_DEV_REPLACE_DEVID, NULL, NULL)) { > + btrfs_err(fs_info, > + "replace devid present without an active replace item"); > + ret = -EIO; > + } else { > + dev_replace->srcdev = NULL; > + dev_replace->tgtdev = NULL; > + } > break; > case BTRFS_IOCTL_DEV_REPLACE_STATE_STARTED: > case BTRFS_IOCTL_DEV_REPLACE_STATE_SUSPENDED: > diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c > index a88655d60a94..0c6049f9ace3 100644 > --- a/fs/btrfs/volumes.c > +++ b/fs/btrfs/volumes.c > @@ -1056,22 +1056,13 @@ static void __btrfs_free_extra_devids(struct btrfs_fs_devices *fs_devices, > continue; > } > > - if (device->devid == BTRFS_DEV_REPLACE_DEVID) { > - /* > - * In the first step, keep the device which has > - * the correct fsid and the devid that is used > - * for the dev_replace procedure. > - * In the second step, the dev_replace state is > - * read from the device tree and it is known > - * whether the procedure is really active or > - * not, which means whether this device is > - * used or whether it should be removed. > - */ > - if (step == 0 || test_bit(BTRFS_DEV_STATE_REPLACE_TGT, > - &device->dev_state)) { > - continue; > - } > - } > + /* > + * We have already validated the presence of BTRFS_DEV_REPLACE_DEVID, > + * in btrfs_init_dev_replace() so just continue. > + */ > + if (device->devid == BTRFS_DEV_REPLACE_DEVID) > + continue; > + > if (device->bdev) { > blkdev_put(device->bdev, device->mode); > device->bdev = NULL; > @@ -1080,9 +1071,6 @@ static void __btrfs_free_extra_devids(struct btrfs_fs_devices *fs_devices, > if (test_bit(BTRFS_DEV_STATE_WRITEABLE, &device->dev_state)) { > list_del_init(&device->dev_alloc_list); > clear_bit(BTRFS_DEV_STATE_WRITEABLE, &device->dev_state); > - if (!test_bit(BTRFS_DEV_STATE_REPLACE_TGT, > - &device->dev_state)) > - fs_devices->rw_devices--; > } > list_del_init(&device->dev_list); > fs_devices->num_devices--; > > base-commit: 1fd4033dd011a3525bacddf37ab9eac425d25c4f > prerequisite-patch-id: 0d3416ab45d924135a9095c3d9c68646f7c5e476 > prerequisite-patch-id: 51a2e9b4b78bf808279307d03436a33063d42130 >
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