kernel.git/fs/nilfs2/super.c, branch linux-6.3.y

nilfs2: fix buffer corruption due to concurrent device reads

2023-06-28T09:14:04Z

commit 679bd7ebdd315bf457a4740b306ae99f1d0a403d upstream. As a result of analysis of a syzbot report, it turned out that in three cases where nilfs2 allocates block device buffers directly via sb_getblk, concurrent reads to the device can corrupt the allocated buffers. Nilfs2 uses sb_getblk for segment summary blocks, that make up a log header, and the super root block, that is the trailer, and when moving and writing the second super block after fs resize. In any of these, since the uptodate flag is not set when storing metadata to be written in the allocated buffers, the stored metadata will be overwritten if a device read of the same block occurs concurrently before the write. This causes metadata corruption and misbehavior in the log write itself, causing warnings in nilfs_btree_assign() as reported. Fix these issues by setting an uptodate flag on the buffer head on the first or before modifying each buffer obtained with sb_getblk, and clearing the flag on failure. When setting the uptodate flag, the lock_buffer/unlock_buffer pair is used to perform necessary exclusive control, and the buffer is filled to ensure that uninitialized bytes are not mixed into the data read from others. As for buffers for segment summary blocks, they are filled incrementally, so if the uptodate flag was unset on their allocation, set the flag and zero fill the buffer once at that point. Also, regarding the superblock move routine, the starting point of the memset call to zerofill the block is incorrectly specified, which can cause a buffer overflow on file systems with block sizes greater than 4KiB. In addition, if the superblock is moved within a large block, it is necessary to assume the possibility that the data in the superblock will be destroyed by zero-filling before copying. So fix these potential issues as well. Link: https://lkml.kernel.org/r/20230609035732.20426-1-konishi.ryusuke@gmail.com Signed-off-by: Ryusuke Konishi Reported-by: syzbot+31837fe952932efc8fb9@syzkaller.appspotmail.com Closes: https://lkml.kernel.org/r/00000000000030000a05e981f475@google.com Tested-by: Ryusuke Konishi Cc: Signed-off-by: Andrew Morton Signed-off-by: Greg Kroah-Hartman

nilfs2: fix sysfs interface lifetime

2023-04-06T01:06:24Z

The current nilfs2 sysfs support has issues with the timing of creation and deletion of sysfs entries, potentially leading to null pointer dereferences, use-after-free, and lockdep warnings. Some of the sysfs attributes for nilfs2 per-filesystem instance refer to metadata file "cpfile", "sufile", or "dat", but nilfs_sysfs_create_device_group that creates those attributes is executed before the inodes for these metadata files are loaded, and nilfs_sysfs_delete_device_group which deletes these sysfs entries is called after releasing their metadata file inodes. Therefore, access to some of these sysfs attributes may occur outside of the lifetime of these metadata files, resulting in inode NULL pointer dereferences or use-after-free. In addition, the call to nilfs_sysfs_create_device_group() is made during the locking period of the semaphore "ns_sem" of nilfs object, so the shrinker call caused by the memory allocation for the sysfs entries, may derive lock dependencies "ns_sem" -> (shrinker) -> "locks acquired in nilfs_evict_inode()". Since nilfs2 may acquire "ns_sem" deep in the call stack holding other locks via its error handler __nilfs_error(), this causes lockdep to report circular locking. This is a false positive and no circular locking actually occurs as no inodes exist yet when nilfs_sysfs_create_device_group() is called. Fortunately, the lockdep warnings can be resolved by simply moving the call to nilfs_sysfs_create_device_group() out of "ns_sem". This fixes these sysfs issues by revising where the device's sysfs interface is created/deleted and keeping its lifetime within the lifetime of the metadata files above. Link: https://lkml.kernel.org/r/20230330205515.6167-1-konishi.ryusuke@gmail.com Fixes: dd70edbde262 ("nilfs2: integrate sysfs support into driver") Signed-off-by: Ryusuke Konishi Reported-by: syzbot+979fa7f9c0d086fdc282@syzkaller.appspotmail.com Link: https://lkml.kernel.org/r/0000000000003414b505f7885f7e@google.com Reported-by: syzbot+5b7d542076d9bddc3c6a@syzkaller.appspotmail.com Link: https://lkml.kernel.org/r/0000000000006ac86605f5f44eb9@google.com Cc: Viacheslav Dubeyko Cc: Signed-off-by: Andrew Morton

nilfs2: fix underflow in second superblock position calculations

2023-02-17T23:07:05Z

Macro NILFS_SB2_OFFSET_BYTES, which computes the position of the second superblock, underflows when the argument device size is less than 4096 bytes. Therefore, when using this macro, it is necessary to check in advance that the device size is not less than a lower limit, or at least that underflow does not occur. The current nilfs2 implementation lacks this check, causing out-of-bound block access when mounting devices smaller than 4096 bytes: I/O error, dev loop0, sector 36028797018963960 op 0x0:(READ) flags 0x0 phys_seg 1 prio class 2 NILFS (loop0): unable to read secondary superblock (blocksize = 1024) In addition, when trying to resize the filesystem to a size below 4096 bytes, this underflow occurs in nilfs_resize_fs(), passing a huge number of segments to nilfs_sufile_resize(), corrupting parameters such as the number of segments in superblocks. This causes excessive loop iterations in nilfs_sufile_resize() during a subsequent resize ioctl, causing semaphore ns_segctor_sem to block for a long time and hang the writer thread: INFO: task segctord:5067 blocked for more than 143 seconds. Not tainted 6.2.0-rc8-syzkaller-00015-gf6feea56f66d #0 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. task:segctord state:D stack:23456 pid:5067 ppid:2 flags:0x00004000 Call Trace: context_switch kernel/sched/core.c:5293 [inline] __schedule+0x1409/0x43f0 kernel/sched/core.c:6606 schedule+0xc3/0x190 kernel/sched/core.c:6682 rwsem_down_write_slowpath+0xfcf/0x14a0 kernel/locking/rwsem.c:1190 nilfs_transaction_lock+0x25c/0x4f0 fs/nilfs2/segment.c:357 nilfs_segctor_thread_construct fs/nilfs2/segment.c:2486 [inline] nilfs_segctor_thread+0x52f/0x1140 fs/nilfs2/segment.c:2570 kthread+0x270/0x300 kernel/kthread.c:376 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:308 ... Call Trace: folio_mark_accessed+0x51c/0xf00 mm/swap.c:515 __nilfs_get_page_block fs/nilfs2/page.c:42 [inline] nilfs_grab_buffer+0x3d3/0x540 fs/nilfs2/page.c:61 nilfs_mdt_submit_block+0xd7/0x8f0 fs/nilfs2/mdt.c:121 nilfs_mdt_read_block+0xeb/0x430 fs/nilfs2/mdt.c:176 nilfs_mdt_get_block+0x12d/0xbb0 fs/nilfs2/mdt.c:251 nilfs_sufile_get_segment_usage_block fs/nilfs2/sufile.c:92 [inline] nilfs_sufile_truncate_range fs/nilfs2/sufile.c:679 [inline] nilfs_sufile_resize+0x7a3/0x12b0 fs/nilfs2/sufile.c:777 nilfs_resize_fs+0x20c/0xed0 fs/nilfs2/super.c:422 nilfs_ioctl_resize fs/nilfs2/ioctl.c:1033 [inline] nilfs_ioctl+0x137c/0x2440 fs/nilfs2/ioctl.c:1301 ... This fixes these issues by inserting appropriate minimum device size checks or anti-underflow checks, depending on where the macro is used. Link: https://lkml.kernel.org/r/0000000000004e1dfa05f4a48e6b@google.com Link: https://lkml.kernel.org/r/20230214224043.24141-1-konishi.ryusuke@gmail.com Signed-off-by: Ryusuke Konishi Reported-by: Tested-by: Ryusuke Konishi Cc: Signed-off-by: Andrew Morton

nilfs2: fix use-after-free bug of ns_writer on remount

2022-11-08T23:57:24Z

If a nilfs2 filesystem is downgraded to read-only due to metadata corruption on disk and is remounted read/write, or if emergency read-only remount is performed, detaching a log writer and synchronizing the filesystem can be done at the same time. In these cases, use-after-free of the log writer (hereinafter nilfs->ns_writer) can happen as shown in the scenario below: Task1 Task2 -------------------------------- ------------------------------ nilfs_construct_segment nilfs_segctor_sync init_wait init_waitqueue_entry add_wait_queue schedule nilfs_remount (R/W remount case) nilfs_attach_log_writer nilfs_detach_log_writer nilfs_segctor_destroy kfree finish_wait _raw_spin_lock_irqsave __raw_spin_lock_irqsave do_raw_spin_lock debug_spin_lock_before <-- use-after-free While Task1 is sleeping, nilfs->ns_writer is freed by Task2. After Task1 waked up, Task1 accesses nilfs->ns_writer which is already freed. This scenario diagram is based on the Shigeru Yoshida's post [1]. This patch fixes the issue by not detaching nilfs->ns_writer on remount so that this UAF race doesn't happen. Along with this change, this patch also inserts a few necessary read-only checks with superblock instance where only the ns_writer pointer was used to check if the filesystem is read-only. Link: https://syzkaller.appspot.com/bug?id=79a4c002e960419ca173d55e863bd09e8112df8b Link: https://lkml.kernel.org/r/20221103141759.1836312-1-syoshida@redhat.com [1] Link: https://lkml.kernel.org/r/20221104142959.28296-1-konishi.ryusuke@gmail.com Signed-off-by: Ryusuke Konishi Reported-by: syzbot+f816fa82f8783f7a02bb@syzkaller.appspotmail.com Reported-by: Shigeru Yoshida Tested-by: Ryusuke Konishi Cc: Signed-off-by: Andrew Morton

nilfs2: fix lockdep warnings in page operations for btree nodes

2022-04-01T18:46:09Z

Patch series "nilfs2 lockdep warning fixes". The first two are to resolve the lockdep warning issue, and the last one is the accompanying cleanup and low priority. Based on your comment, this series solves the issue by separating inode object as needed. Since I was worried about the impact of the object composition changes, I tested the series carefully not to cause regressions especially for delicate functions such like disk space reclamation and snapshots. This patch (of 3): If CONFIG_LOCKDEP is enabled, nilfs2 hits lockdep warnings at inode_to_wb() during page/folio operations for btree nodes: WARNING: CPU: 0 PID: 6575 at include/linux/backing-dev.h:269 inode_to_wb include/linux/backing-dev.h:269 [inline] WARNING: CPU: 0 PID: 6575 at include/linux/backing-dev.h:269 folio_account_dirtied mm/page-writeback.c:2460 [inline] WARNING: CPU: 0 PID: 6575 at include/linux/backing-dev.h:269 __folio_mark_dirty+0xa7c/0xe30 mm/page-writeback.c:2509 Modules linked in: ... RIP: 0010:inode_to_wb include/linux/backing-dev.h:269 [inline] RIP: 0010:folio_account_dirtied mm/page-writeback.c:2460 [inline] RIP: 0010:__folio_mark_dirty+0xa7c/0xe30 mm/page-writeback.c:2509 ... Call Trace: __set_page_dirty include/linux/pagemap.h:834 [inline] mark_buffer_dirty+0x4e6/0x650 fs/buffer.c:1145 nilfs_btree_propagate_p fs/nilfs2/btree.c:1889 [inline] nilfs_btree_propagate+0x4ae/0xea0 fs/nilfs2/btree.c:2085 nilfs_bmap_propagate+0x73/0x170 fs/nilfs2/bmap.c:337 nilfs_collect_dat_data+0x45/0xd0 fs/nilfs2/segment.c:625 nilfs_segctor_apply_buffers+0x14a/0x470 fs/nilfs2/segment.c:1009 nilfs_segctor_scan_file+0x47a/0x700 fs/nilfs2/segment.c:1048 nilfs_segctor_collect_blocks fs/nilfs2/segment.c:1224 [inline] nilfs_segctor_collect fs/nilfs2/segment.c:1494 [inline] nilfs_segctor_do_construct+0x14f3/0x6c60 fs/nilfs2/segment.c:2036 nilfs_segctor_construct+0x7a7/0xb30 fs/nilfs2/segment.c:2372 nilfs_segctor_thread_construct fs/nilfs2/segment.c:2480 [inline] nilfs_segctor_thread+0x3c3/0xf90 fs/nilfs2/segment.c:2563 kthread+0x405/0x4f0 kernel/kthread.c:327 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295 This is because nilfs2 uses two page caches for each inode and inode->i_mapping never points to one of them, the btree node cache. This causes inode_to_wb(inode) to refer to a different page cache than the caller page/folio operations such like __folio_start_writeback(), __folio_end_writeback(), or __folio_mark_dirty() acquired the lock. This patch resolves the issue by allocating and using an additional inode to hold the page cache of btree nodes. The inode is attached one-to-one to the traditional nilfs2 inode if it requires a block mapping with b-tree. This setup change is in memory only and does not affect the disk format. Link: https://lkml.kernel.org/r/1647867427-30498-1-git-send-email-konishi.ryusuke@gmail.com Link: https://lkml.kernel.org/r/1647867427-30498-2-git-send-email-konishi.ryusuke@gmail.com Link: https://lore.kernel.org/r/YXrYvIo8YRnAOJCj@casper.infradead.org Link: https://lore.kernel.org/r/9a20b33d-b38f-b4a2-4742-c1eb5b8e4d6c@redhat.com Signed-off-by: Ryusuke Konishi Reported-by: syzbot+0d5b462a6f07447991b3@syzkaller.appspotmail.com Reported-by: syzbot+34ef28bb2aeb28724aa0@syzkaller.appspotmail.com Reported-by: Hao Sun Reported-by: David Hildenbrand Tested-by: Ryusuke Konishi Cc: Matthew Wilcox Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

fs: allocate inode by using alloc_inode_sb()

2022-03-22T22:57:03Z

The inode allocation is supposed to use alloc_inode_sb(), so convert kmem_cache_alloc() of all filesystems to alloc_inode_sb(). Link: https://lkml.kernel.org/r/20220228122126.37293-5-songmuchun@bytedance.com Signed-off-by: Muchun Song Acked-by: Theodore Ts'o [ext4] Acked-by: Roman Gushchin Cc: Alex Shi Cc: Anna Schumaker Cc: Chao Yu Cc: Dave Chinner Cc: Fam Zheng Cc: Jaegeuk Kim Cc: Johannes Weiner Cc: Kari Argillander Cc: Matthew Wilcox (Oracle) Cc: Michal Hocko Cc: Qi Zheng Cc: Shakeel Butt Cc: Trond Myklebust Cc: Vladimir Davydov Cc: Vlastimil Babka Cc: Wei Yang Cc: Xiongchun Duan Cc: Yang Shi Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

Merge branch 'akpm' (patches from Andrew)

2021-11-09T18:11:53Z

Merge more updates from Andrew Morton: "87 patches. Subsystems affected by this patch series: mm (pagecache and hugetlb), procfs, misc, MAINTAINERS, lib, checkpatch, binfmt, kallsyms, ramfs, init, codafs, nilfs2, hfs, crash_dump, signals, seq_file, fork, sysvfs, kcov, gdb, resource, selftests, and ipc" * emailed patches from Andrew Morton : (87 commits) ipc/ipc_sysctl.c: remove fallback for !CONFIG_PROC_SYSCTL ipc: check checkpoint_restore_ns_capable() to modify C/R proc files selftests/kselftest/runner/run_one(): allow running non-executable files virtio-mem: disallow mapping virtio-mem memory via /dev/mem kernel/resource: disallow access to exclusive system RAM regions kernel/resource: clean up and optimize iomem_is_exclusive() scripts/gdb: handle split debug for vmlinux kcov: replace local_irq_save() with a local_lock_t kcov: avoid enable+disable interrupts if !in_task() kcov: allocate per-CPU memory on the relevant node Documentation/kcov: define `ip' in the example Documentation/kcov: include types.h in the example sysv: use BUILD_BUG_ON instead of runtime check kernel/fork.c: unshare(): use swap() to make code cleaner seq_file: fix passing wrong private data seq_file: move seq_escape() to a header signal: remove duplicate include in signal.h crash_dump: remove duplicate include in crash_dump.h crash_dump: fix boolreturn.cocci warning hfs/hfsplus: use WARN_ON for sanity check ...

nilfs2: remove filenames from file comments

2021-11-09T18:02:52Z

Remove filenames that are not particularly useful in file comments, and suppress checkpatch warnings WARNING: It's generally not useful to have the filename in the file Link: https://lkml.kernel.org/r/1635151862-11547-3-git-send-email-konishi.ryusuke@gmail.com Signed-off-by: Ryusuke Konishi Cc: Qing Wang Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

nilfs2: use bdev_nr_bytes instead of open coding it

2021-10-18T20:43:23Z

Use the proper helper to read the block device size. Signed-off-by: Christoph Hellwig Reviewed-by: Kees Cook Acked-by: Ryusuke Konishi Link: https://lore.kernel.org/r/20211018101130.1838532-20-hch@lst.de Signed-off-by: Jens Axboe

block: remove the bd_bdi in struct block_device

2021-08-09T17:53:26Z

Just retrieve the bdi from the disk. Signed-off-by: Christoph Hellwig Reviewed-by: Jan Kara Reviewed-by: Johannes Thumshirn Link: https://lore.kernel.org/r/20210809141744.1203023-6-hch@lst.de Signed-off-by: Jens Axboe