kernel/linux.git/fs/inode.c, branch v6.6.132

fs/inode: Prevent dump_mapping() accessing invalid dentry.d_name.name

2024-12-09T09:31:41+00:00

[ Upstream commit 7f7b850689ac06a62befe26e1fd1806799e7f152 ] It's observed that a crash occurs during hot-remove a memory device, in which user is accessing the hugetlb. See calltrace as following: ------------[ cut here ]------------ WARNING: CPU: 1 PID: 14045 at arch/x86/mm/fault.c:1278 do_user_addr_fault+0x2a0/0x790 Modules linked in: kmem device_dax cxl_mem cxl_pmem cxl_port cxl_pci dax_hmem dax_pmem nd_pmem cxl_acpi nd_btt cxl_core crc32c_intel nvme virtiofs fuse nvme_core nfit libnvdimm dm_multipath scsi_dh_rdac scsi_dh_emc s mirror dm_region_hash dm_log dm_mod CPU: 1 PID: 14045 Comm: daxctl Not tainted 6.10.0-rc2-lizhijian+ #492 Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS rel-1.16.3-0-ga6ed6b701f0a-prebuilt.qemu.org 04/01/2014 RIP: 0010:do_user_addr_fault+0x2a0/0x790 Code: 48 8b 00 a8 04 0f 84 b5 fe ff ff e9 1c ff ff ff 4c 89 e9 4c 89 e2 be 01 00 00 00 bf 02 00 00 00 e8 b5 ef 24 00 e9 42 fe ff ff <0f> 0b 48 83 c4 08 4c 89 ea 48 89 ee 4c 89 e7 5b 5d 41 5c 41 5d 41 RSP: 0000:ffffc90000a575f0 EFLAGS: 00010046 RAX: ffff88800c303600 RBX: 0000000000000000 RCX: 0000000000000000 RDX: 0000000000001000 RSI: ffffffff82504162 RDI: ffffffff824b2c36 RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000000 R12: ffffc90000a57658 R13: 0000000000001000 R14: ffff88800bc2e040 R15: 0000000000000000 FS: 00007f51cb57d880(0000) GS:ffff88807fd00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000000000001000 CR3: 00000000072e2004 CR4: 00000000001706f0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: ? __warn+0x8d/0x190 ? do_user_addr_fault+0x2a0/0x790 ? report_bug+0x1c3/0x1d0 ? handle_bug+0x3c/0x70 ? exc_invalid_op+0x14/0x70 ? asm_exc_invalid_op+0x16/0x20 ? do_user_addr_fault+0x2a0/0x790 ? exc_page_fault+0x31/0x200 exc_page_fault+0x68/0x200 <...snip...> BUG: unable to handle page fault for address: 0000000000001000 #PF: supervisor read access in kernel mode #PF: error_code(0x0000) - not-present page PGD 800000000ad92067 P4D 800000000ad92067 PUD 7677067 PMD 0 Oops: Oops: 0000 [#1] PREEMPT SMP PTI ---[ end trace 0000000000000000 ]--- BUG: unable to handle page fault for address: 0000000000001000 #PF: supervisor read access in kernel mode #PF: error_code(0x0000) - not-present page PGD 800000000ad92067 P4D 800000000ad92067 PUD 7677067 PMD 0 Oops: Oops: 0000 [#1] PREEMPT SMP PTI CPU: 1 PID: 14045 Comm: daxctl Kdump: loaded Tainted: G W 6.10.0-rc2-lizhijian+ #492 Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS rel-1.16.3-0-ga6ed6b701f0a-prebuilt.qemu.org 04/01/2014 RIP: 0010:dentry_name+0x1f4/0x440 <...snip...> ? dentry_name+0x2fa/0x440 vsnprintf+0x1f3/0x4f0 vprintk_store+0x23a/0x540 vprintk_emit+0x6d/0x330 _printk+0x58/0x80 dump_mapping+0x10b/0x1a0 ? __pfx_free_object_rcu+0x10/0x10 __dump_page+0x26b/0x3e0 ? vprintk_emit+0xe0/0x330 ? _printk+0x58/0x80 ? dump_page+0x17/0x50 dump_page+0x17/0x50 do_migrate_range+0x2f7/0x7f0 ? do_migrate_range+0x42/0x7f0 ? offline_pages+0x2f4/0x8c0 offline_pages+0x60a/0x8c0 memory_subsys_offline+0x9f/0x1c0 ? lockdep_hardirqs_on+0x77/0x100 ? _raw_spin_unlock_irqrestore+0x38/0x60 device_offline+0xe3/0x110 state_store+0x6e/0xc0 kernfs_fop_write_iter+0x143/0x200 vfs_write+0x39f/0x560 ksys_write+0x65/0xf0 do_syscall_64+0x62/0x130 Previously, some sanity check have been done in dump_mapping() before the print facility parsing '%pd' though, it's still possible to run into an invalid dentry.d_name.name. Since dump_mapping() only needs to dump the filename only, retrieve it by itself in a safer way to prevent an unnecessary crash. Note that either retrieving the filename with '%pd' or strncpy_from_kernel_nofault(), the filename could be unreliable. Signed-off-by: Li Zhijian Link: https://lore.kernel.org/r/20240826055503.1522320-1-lizhijian@fujitsu.com Reviewed-by: Jan Kara Signed-off-by: Christian Brauner Signed-off-by: Sasha Levin [Xiangyu: Bp to fix CVE: CVE-2024-49934, modified strscpy step due to 6.1/6.6 need pass the max len to strscpy] Signed-off-by: Xiangyu Chen Signed-off-by: Sasha Levin

vfs: fix race between evice_inodes() and find_inode()&iput()

2024-10-04T14:29:56+00:00

commit 88b1afbf0f6b221f6c5bb66cc80cd3b38d696687 upstream. Hi, all Recently I noticed a bug[1] in btrfs, after digged it into and I believe it'a race in vfs. Let's assume there's a inode (ie ino 261) with i_count 1 is called by iput(), and there's a concurrent thread calling generic_shutdown_super(). cpu0: cpu1: iput() // i_count is 1 ->spin_lock(inode) ->dec i_count to 0 ->iput_final() generic_shutdown_super() ->__inode_add_lru() ->evict_inodes() // cause some reason[2] ->if (atomic_read(inode->i_count)) continue; // return before // inode 261 passed the above check // list_lru_add_obj() // and then schedule out ->spin_unlock() // note here: the inode 261 // was still at sb list and hash list, // and I_FREEING|I_WILL_FREE was not been set btrfs_iget() // after some function calls ->find_inode() // found the above inode 261 ->spin_lock(inode) // check I_FREEING|I_WILL_FREE // and passed ->__iget() ->spin_unlock(inode) // schedule back ->spin_lock(inode) // check (I_NEW|I_FREEING|I_WILL_FREE) flags, // passed and set I_FREEING iput() ->spin_unlock(inode) ->spin_lock(inode) ->evict() // dec i_count to 0 ->iput_final() ->spin_unlock() ->evict() Now, we have two threads simultaneously evicting the same inode, which may trigger the BUG(inode->i_state & I_CLEAR) statement both within clear_inode() and iput(). To fix the bug, recheck the inode->i_count after holding i_lock. Because in the most scenarios, the first check is valid, and the overhead of spin_lock() can be reduced. If there is any misunderstanding, please let me know, thanks. [1]: https://lore.kernel.org/linux-btrfs/000000000000eabe1d0619c48986@google.com/ [2]: The reason might be 1. SB_ACTIVE was removed or 2. mapping_shrinkable() return false when I reproduced the bug. Reported-by: syzbot+67ba3c42bcbb4665d3ad@syzkaller.appspotmail.com Closes: https://syzkaller.appspot.com/bug?extid=67ba3c42bcbb4665d3ad CC: stable@vger.kernel.org Fixes: 63997e98a3be ("split invalidate_inodes()") Signed-off-by: Julian Sun Link: https://lore.kernel.org/r/20240823130730.658881-1-sunjunchao2870@gmail.com Reviewed-by: Jan Kara Signed-off-by: Christian Brauner Signed-off-by: Greg Kroah-Hartman

vfs: Don't evict inode under the inode lru traversing context

2024-08-29T15:33:13+00:00

commit 2a0629834cd82f05d424bbc193374f9a43d1f87d upstream. The inode reclaiming process(See function prune_icache_sb) collects all reclaimable inodes and mark them with I_FREEING flag at first, at that time, other processes will be stuck if they try getting these inodes (See function find_inode_fast), then the reclaiming process destroy the inodes by function dispose_list(). Some filesystems(eg. ext4 with ea_inode feature, ubifs with xattr) may do inode lookup in the inode evicting callback function, if the inode lookup is operated under the inode lru traversing context, deadlock problems may happen. Case 1: In function ext4_evict_inode(), the ea inode lookup could happen if ea_inode feature is enabled, the lookup process will be stuck under the evicting context like this: 1. File A has inode i_reg and an ea inode i_ea 2. getfattr(A, xattr_buf) // i_ea is added into lru // lru->i_ea 3. Then, following three processes running like this: PA PB echo 2 > /proc/sys/vm/drop_caches shrink_slab prune_dcache_sb // i_reg is added into lru, lru->i_ea->i_reg prune_icache_sb list_lru_walk_one inode_lru_isolate i_ea->i_state |= I_FREEING // set inode state inode_lru_isolate __iget(i_reg) spin_unlock(&i_reg->i_lock) spin_unlock(lru_lock) rm file A i_reg->nlink = 0 iput(i_reg) // i_reg->nlink is 0, do evict ext4_evict_inode ext4_xattr_delete_inode ext4_xattr_inode_dec_ref_all ext4_xattr_inode_iget ext4_iget(i_ea->i_ino) iget_locked find_inode_fast __wait_on_freeing_inode(i_ea) ----→ AA deadlock dispose_list // cannot be executed by prune_icache_sb wake_up_bit(&i_ea->i_state) Case 2: In deleted inode writing function ubifs_jnl_write_inode(), file deleting process holds BASEHD's wbuf->io_mutex while getting the xattr inode, which could race with inode reclaiming process(The reclaiming process could try locking BASEHD's wbuf->io_mutex in inode evicting function), then an ABBA deadlock problem would happen as following: 1. File A has inode ia and a xattr(with inode ixa), regular file B has inode ib and a xattr. 2. getfattr(A, xattr_buf) // ixa is added into lru // lru->ixa 3. Then, following three processes running like this: PA PB PC echo 2 > /proc/sys/vm/drop_caches shrink_slab prune_dcache_sb // ib and ia are added into lru, lru->ixa->ib->ia prune_icache_sb list_lru_walk_one inode_lru_isolate ixa->i_state |= I_FREEING // set inode state inode_lru_isolate __iget(ib) spin_unlock(&ib->i_lock) spin_unlock(lru_lock) rm file B ib->nlink = 0 rm file A iput(ia) ubifs_evict_inode(ia) ubifs_jnl_delete_inode(ia) ubifs_jnl_write_inode(ia) make_reservation(BASEHD) // Lock wbuf->io_mutex ubifs_iget(ixa->i_ino) iget_locked find_inode_fast __wait_on_freeing_inode(ixa) | iput(ib) // ib->nlink is 0, do evict | ubifs_evict_inode | ubifs_jnl_delete_inode(ib) ↓ ubifs_jnl_write_inode ABBA deadlock ←-----make_reservation(BASEHD) dispose_list // cannot be executed by prune_icache_sb wake_up_bit(&ixa->i_state) Fix the possible deadlock by using new inode state flag I_LRU_ISOLATING to pin the inode in memory while inode_lru_isolate() reclaims its pages instead of using ordinary inode reference. This way inode deletion cannot be triggered from inode_lru_isolate() thus avoiding the deadlock. evict() is made to wait for I_LRU_ISOLATING to be cleared before proceeding with inode cleanup. Link: https://lore.kernel.org/all/37c29c42-7685-d1f0-067d-63582ffac405@huaweicloud.com/ Link: https://bugzilla.kernel.org/show_bug.cgi?id=219022 Fixes: e50e5129f384 ("ext4: xattr-in-inode support") Fixes: 7959cf3a7506 ("ubifs: journal: Handle xattrs like files") Cc: stable@vger.kernel.org Signed-off-by: Zhihao Cheng Link: https://lore.kernel.org/r/20240809031628.1069873-1-chengzhihao@huaweicloud.com Reviewed-by: Jan Kara Suggested-by: Jan Kara Suggested-by: Mateusz Guzik Signed-off-by: Christian Brauner Signed-off-by: Greg Kroah-Hartman

filemap: add a per-mapping stable writes flag

2023-12-03T06:33:03+00:00

[ Upstream commit 762321dab9a72760bf9aec48362f932717c9424d ] folio_wait_stable waits for writeback to finish before modifying the contents of a folio again, e.g. to support check summing of the data in the block integrity code. Currently this behavior is controlled by the SB_I_STABLE_WRITES flag on the super_block, which means it is uniform for the entire file system. This is wrong for the block device pseudofs which is shared by all block devices, or file systems that can use multiple devices like XFS witht the RT subvolume or btrfs (although btrfs currently reimplements folio_wait_stable anyway). Add a per-address_space AS_STABLE_WRITES flag to control the behavior in a more fine grained way. The existing SB_I_STABLE_WRITES is kept to initialize AS_STABLE_WRITES to the existing default which covers most cases. Signed-off-by: Christoph Hellwig Link: https://lore.kernel.org/r/20231025141020.192413-2-hch@lst.de Tested-by: Ilya Dryomov Reviewed-by: Matthew Wilcox (Oracle) Reviewed-by: Darrick J. Wong Signed-off-by: Christian Brauner Stable-dep-of: 1898efcdbed3 ("block: update the stable_writes flag in bdev_add") Signed-off-by: Sasha Levin

Revert "fs: add infrastructure for multigrain timestamps"

2023-09-20T16:05:31+00:00

This reverts commit ffb6cf19e06334062744b7e3493f71e500964f8e. Users reported regressions due to enabling multi-grained timestamps unconditionally. As no clear consensus on a solution has come up and the discussion has gone back to the drawing board revert the infrastructure changes for. If it isn't code that's here to stay, make it go away. Message-ID: <20230920-keine-eile-c9755b5825db@brauner> Acked-by: Jan Kara Acked-by: Jeff Layton Signed-off-by: Christian Brauner

Merge tag 'v6.6-vfs.super' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs

2023-08-28T18:04:18+00:00

Pull superblock updates from Christian Brauner: "This contains the super rework that was ready for this cycle. The first part changes the order of how we open block devices and allocate superblocks, contains various cleanups, simplifications, and a new mechanism to wait on superblock state changes. This unblocks work to ultimately limit the number of writers to a block device. Jan has already scheduled follow-up work that will be ready for v6.7 and allows us to restrict the number of writers to a given block device. That series builds on this work right here. The second part contains filesystem freezing updates. Overview: The generic superblock changes are rougly organized as follows (ignoring additional minor cleanups): (1) Removal of the bd_super member from struct block_device. This was a very odd back pointer to struct super_block with unclear rules. For all relevant places we have other means to get the same information so just get rid of this. (2) Simplify rules for superblock cleanup. Roughly, everything that is allocated during fs_context initialization and that's stored in fs_context->s_fs_info needs to be cleaned up by the fs_context->free() implementation before the superblock allocation function has been called successfully. After sget_fc() returned fs_context->s_fs_info has been transferred to sb->s_fs_info at which point sb->kill_sb() if fully responsible for cleanup. Adhering to these rules means that cleanup of sb->s_fs_info in fill_super() is to be avoided as it's brittle and inconsistent. Cleanup shouldn't be duplicated between sb->put_super() as sb->put_super() is only called if sb->s_root has been set aka when the filesystem has been successfully born (SB_BORN). That complexity should be avoided. This also means that block devices are to be closed in sb->kill_sb() instead of sb->put_super(). More details in the lower section. (3) Make it possible to lookup or create a superblock before opening block devices There's a subtle dependency on (2) as some filesystems did rely on fill_super() to be called in order to correctly clean up sb->s_fs_info. All these filesystems have been fixed. (4) Switch most filesystem to follow the same logic as the generic mount code now does as outlined in (3). (5) Use the superblock as the holder of the block device. We can now easily go back from block device to owning superblock. (6) Export and extend the generic fs_holder_ops and use them as holder ops everywhere and remove the filesystem specific holder ops. (7) Call from the block layer up into the filesystem layer when the block device is removed, allowing to shut down the filesystem without risk of deadlocks. (8) Get rid of get_super(). We can now easily go back from the block device to owning superblock and can call up from the block layer into the filesystem layer when the device is removed. So no need to wade through all registered superblock to find the owning superblock anymore" Link: https://lore.kernel.org/lkml/20230824-prall-intakt-95dbffdee4a0@brauner/ * tag 'v6.6-vfs.super' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs: (47 commits) super: use higher-level helper for {freeze,thaw} super: wait until we passed kill super super: wait for nascent superblocks super: make locking naming consistent super: use locking helpers fs: simplify invalidate_inodes fs: remove get_super block: call into the file system for ioctl BLKFLSBUF block: call into the file system for bdev_mark_dead block: consolidate __invalidate_device and fsync_bdev block: drop the "busy inodes on changed media" log message dasd: also call __invalidate_device when setting the device offline amiflop: don't call fsync_bdev in FDFMTBEG floppy: call disk_force_media_change when changing the format block: simplify the disk_force_media_change interface nbd: call blk_mark_disk_dead in nbd_clear_sock_ioctl xfs use fs_holder_ops for the log and RT devices xfs: drop s_umount over opening the log and RT devices ext4: use fs_holder_ops for the log device ext4: drop s_umount over opening the log device ...

Merge tag 'v6.6-vfs.ctime' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs

2023-08-28T16:31:32+00:00

Pull vfs timestamp updates from Christian Brauner: "This adds VFS support for multi-grain timestamps and converts tmpfs, xfs, ext4, and btrfs to use them. This carries acks from all relevant filesystems. The VFS always uses coarse-grained timestamps when updating the ctime and mtime after a change. This has the benefit of allowing filesystems to optimize away a lot of metadata updates, down to around 1 per jiffy, even when a file is under heavy writes. Unfortunately, this has always been an issue when we're exporting via NFSv3, which relies on timestamps to validate caches. A lot of changes can happen in a jiffy, so timestamps aren't sufficient to help the client decide to invalidate the cache. Even with NFSv4, a lot of exported filesystems don't properly support a change attribute and are subject to the same problems with timestamp granularity. Other applications have similar issues with timestamps (e.g., backup applications). If we were to always use fine-grained timestamps, that would improve the situation, but that becomes rather expensive, as the underlying filesystem would have to log a lot more metadata updates. This introduces fine-grained timestamps that are used when they are actively queried. This uses the 31st bit of the ctime tv_nsec field to indicate that something has queried the inode for the mtime or ctime. When this flag is set, on the next mtime or ctime update, the kernel will fetch a fine-grained timestamp instead of the usual coarse-grained one. As POSIX generally mandates that when the mtime changes, the ctime must also change the kernel always stores normalized ctime values, so only the first 30 bits of the tv_nsec field are ever used. Filesytems can opt into this behavior by setting the FS_MGTIME flag in the fstype. Filesystems that don't set this flag will continue to use coarse-grained timestamps. Various preparatory changes, fixes and cleanups are included: - Fixup all relevant places where POSIX requires updating ctime together with mtime. This is a wide-range of places and all maintainers provided necessary Acks. - Add new accessors for inode->i_ctime directly and change all callers to rely on them. Plain accesses to inode->i_ctime are now gone and it is accordingly rename to inode->__i_ctime and commented as requiring accessors. - Extend generic_fillattr() to pass in a request mask mirroring in a sense the statx() uapi. This allows callers to pass in a request mask to only get a subset of attributes filled in. - Rework timestamp updates so it's possible to drop the @now parameter the update_time() inode operation and associated helpers. - Add inode_update_timestamps() and convert all filesystems to it removing a bunch of open-coding" * tag 'v6.6-vfs.ctime' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs: (107 commits) btrfs: convert to multigrain timestamps ext4: switch to multigrain timestamps xfs: switch to multigrain timestamps tmpfs: add support for multigrain timestamps fs: add infrastructure for multigrain timestamps fs: drop the timespec64 argument from update_time xfs: have xfs_vn_update_time gets its own timestamp fat: make fat_update_time get its own timestamp fat: remove i_version handling from fat_update_time ubifs: have ubifs_update_time use inode_update_timestamps btrfs: have it use inode_update_timestamps fs: drop the timespec64 arg from generic_update_time fs: pass the request_mask to generic_fillattr fs: remove silly warning from current_time gfs2: fix timestamp handling on quota inodes fs: rename i_ctime field to __i_ctime selinux: convert to ctime accessor functions security: convert to ctime accessor functions apparmor: convert to ctime accessor functions sunrpc: convert to ctime accessor functions ...

fs: simplify invalidate_inodes

2023-08-21T12:35:32+00:00

kill_dirty has always been true for a long time, so hard code it and remove the unused return value. Signed-off-by: Christoph Hellwig Reviewed-by: Christian Brauner Reviewed-by: Josef Bacik Message-Id: <20230811100828.1897174-18-hch@lst.de> Signed-off-by: Christian Brauner

locking: remove spin_lock_prefetch

2023-08-12T16:18:47+00:00

The only remaining consumer is new_inode, where it showed up in 2001 as commit c37fa164f793 ("v2.4.9.9 -> v2.4.9.10") in a historical repo [1] with a changelog which does not mention it. Since then the line got only touched up to keep compiling. While it may have been of benefit back in the day, it is guaranteed to at best not get in the way in the multicore setting -- as the code performs *a lot* of work between the prefetch and actual lock acquire, any contention means the cacheline is already invalid by the time the routine calls spin_lock(). It adds spurious traffic, for short. On top of it prefetch is notoriously tricky to use for single-threaded purposes, making it questionable from the get go. As such, remove it. I admit upfront I did not see value in benchmarking this change, but I can do it if that is deemed appropriate. Removal from new_inode and of the entire thing are in the same patch as requested by Linus, so whatever weird looks can be directed at that guy. Link: https://git.kernel.org/pub/scm/linux/kernel/git/tglx/history.git/commit/fs/inode.c?id=c37fa164f793735b32aa3f53154ff1a7659e6442 [1] Signed-off-by: Mateusz Guzik Signed-off-by: Linus Torvalds

fs: add infrastructure for multigrain timestamps

2023-08-11T07:04:57+00:00

The VFS always uses coarse-grained timestamps when updating the ctime and mtime after a change. This has the benefit of allowing filesystems to optimize away a lot metadata updates, down to around 1 per jiffy, even when a file is under heavy writes. Unfortunately, this has always been an issue when we're exporting via NFSv3, which relies on timestamps to validate caches. A lot of changes can happen in a jiffy, so timestamps aren't sufficient to help the client decide to invalidate the cache. Even with NFSv4, a lot of exported filesystems don't properly support a change attribute and are subject to the same problems with timestamp granularity. Other applications have similar issues with timestamps (e.g backup applications). If we were to always use fine-grained timestamps, that would improve the situation, but that becomes rather expensive, as the underlying filesystem would have to log a lot more metadata updates. What we need is a way to only use fine-grained timestamps when they are being actively queried. POSIX generally mandates that when the the mtime changes, the ctime must also change. The kernel always stores normalized ctime values, so only the first 30 bits of the tv_nsec field are ever used. Use the 31st bit of the ctime tv_nsec field to indicate that something has queried the inode for the mtime or ctime. When this flag is set, on the next mtime or ctime update, the kernel will fetch a fine-grained timestamp instead of the usual coarse-grained one. Filesytems can opt into this behavior by setting the FS_MGTIME flag in the fstype. Filesystems that don't set this flag will continue to use coarse-grained timestamps. Later patches will convert individual filesystems to use the new infrastructure. Signed-off-by: Jeff Layton Reviewed-by: Jan Kara Message-Id: <20230807-mgctime-v7-9-d1dec143a704@kernel.org> Signed-off-by: Christian Brauner