kernel.git/fs/ubifs, branch linux-5.16.y

ubifs: rename_whiteout: correct old_dir size computing

2022-04-08T12:06:48Z

commit 705757274599e2e064dd3054aabc74e8af31a095 upstream. When renaming the whiteout file, the old whiteout file is not deleted. Therefore, we add the old dentry size to the old dir like XFS. Otherwise, an error may be reported due to `fscki->calc_sz != fscki->size` in check_indes. Fixes: 9e0a1fff8db56ea ("ubifs: Implement RENAME_WHITEOUT") Reported-by: Zhihao Cheng Signed-off-by: Baokun Li Signed-off-by: Richard Weinberger Signed-off-by: Greg Kroah-Hartman

ubifs: Fix to add refcount once page is set private

2022-04-08T12:06:48Z

commit 3b67db8a6ca83e6ff90b756d3da0c966f61cd37b upstream. MM defined the rule [1] very clearly that once page was set with PG_private flag, we should increment the refcount in that page, also main flows like pageout(), migrate_page() will assume there is one additional page reference count if page_has_private() returns true. Otherwise, we may get a BUG in page migration: page:0000000080d05b9d refcount:-1 mapcount:0 mapping:000000005f4d82a8 index:0xe2 pfn:0x14c12 aops:ubifs_file_address_operations [ubifs] ino:8f1 dentry name:"f30e" flags: 0x1fffff80002405(locked|uptodate|owner_priv_1|private|node=0| zone=1|lastcpupid=0x1fffff) page dumped because: VM_BUG_ON_PAGE(page_count(page) != 0) ------------[ cut here ]------------ kernel BUG at include/linux/page_ref.h:184! invalid opcode: 0000 [#1] SMP CPU: 3 PID: 38 Comm: kcompactd0 Not tainted 5.15.0-rc5 RIP: 0010:migrate_page_move_mapping+0xac3/0xe70 Call Trace: ubifs_migrate_page+0x22/0xc0 [ubifs] move_to_new_page+0xb4/0x600 migrate_pages+0x1523/0x1cc0 compact_zone+0x8c5/0x14b0 kcompactd+0x2bc/0x560 kthread+0x18c/0x1e0 ret_from_fork+0x1f/0x30 Before the time, we should make clean a concept, what does refcount means in page gotten from grab_cache_page_write_begin(). There are 2 situations: Situation 1: refcount is 3, page is created by __page_cache_alloc. TYPE_A - the write process is using this page TYPE_B - page is assigned to one certain mapping by calling __add_to_page_cache_locked() TYPE_C - page is added into pagevec list corresponding current cpu by calling lru_cache_add() Situation 2: refcount is 2, page is gotten from the mapping's tree TYPE_B - page has been assigned to one certain mapping TYPE_A - the write process is using this page (by calling page_cache_get_speculative()) Filesystem releases one refcount by calling put_page() in xxx_write_end(), the released refcount corresponds to TYPE_A (write task is using it). If there are any processes using a page, page migration process will skip the page by judging whether expected_page_refs() equals to page refcount. The BUG is caused by following process: PA(cpu 0) kcompactd(cpu 1) compact_zone ubifs_write_begin page_a = grab_cache_page_write_begin add_to_page_cache_lru lru_cache_add pagevec_add // put page into cpu 0's pagevec (refcnf = 3, for page creation process) ubifs_write_end SetPagePrivate(page_a) // doesn't increase page count ! unlock_page(page_a) put_page(page_a) // refcnt = 2 [...] PB(cpu 0) filemap_read filemap_get_pages add_to_page_cache_lru lru_cache_add __pagevec_lru_add // traverse all pages in cpu 0's pagevec __pagevec_lru_add_fn SetPageLRU(page_a) isolate_migratepages isolate_migratepages_block get_page_unless_zero(page_a) // refcnt = 3 list_add(page_a, from_list) migrate_pages(from_list) __unmap_and_move move_to_new_page ubifs_migrate_page(page_a) migrate_page_move_mapping expected_page_refs get 3 (migration[1] + mapping[1] + private[1]) release_pages put_page_testzero(page_a) // refcnt = 3 page_ref_freeze // refcnt = 0 page_ref_dec_and_test(0 - 1 = -1) page_ref_unfreeze VM_BUG_ON_PAGE(-1 != 0, page) UBIFS doesn't increase the page refcount after setting private flag, which leads to page migration task believes the page is not used by any other processes, so the page is migrated. This causes concurrent accessing on page refcount between put_page() called by other process(eg. read process calls lru_cache_add) and page_ref_unfreeze() called by migration task. Actually zhangjun has tried to fix this problem [2] by recalculating page refcnt in ubifs_migrate_page(). It's better to follow MM rules [1], because just like Kirill suggested in [2], we need to check all users of page_has_private() helper. Like f2fs does in [3], fix it by adding/deleting refcount when setting/clearing private for a page. BTW, according to [4], we set 'page->private' as 1 because ubifs just simply SetPagePrivate(). And, [5] provided a common helper to set/clear page private, ubifs can use this helper following the example of iomap, afs, btrfs, etc. Jump [6] to find a reproducer. [1] https://lore.kernel.org/lkml/2b19b3c4-2bc4-15fa-15cc-27a13e5c7af1@aol.com [2] https://www.spinics.net/lists/linux-mtd/msg04018.html [3] http://lkml.iu.edu/hypermail/linux/kernel/1903.0/03313.html [4] https://lore.kernel.org/linux-f2fs-devel/20210422154705.GO3596236@casper.infradead.org [5] https://lore.kernel.org/all/20200517214718.468-1-guoqing.jiang@cloud.ionos.com [6] https://bugzilla.kernel.org/show_bug.cgi?id=214961 Fixes: 1e51764a3c2ac0 ("UBIFS: add new flash file system") Signed-off-by: Zhihao Cheng Signed-off-by: Richard Weinberger Signed-off-by: Greg Kroah-Hartman

ubifs: Fix read out-of-bounds in ubifs_wbuf_write_nolock()

2022-04-08T12:06:48Z

commit 4f2262a334641e05f645364d5ade1f565c85f20b upstream. Function ubifs_wbuf_write_nolock() may access buf out of bounds in following process: ubifs_wbuf_write_nolock(): aligned_len = ALIGN(len, 8); // Assume len = 4089, aligned_len = 4096 if (aligned_len <= wbuf->avail) ... // Not satisfy if (wbuf->used) { ubifs_leb_write() // Fill some data in avail wbuf len -= wbuf->avail; // len is still not 8-bytes aligned aligned_len -= wbuf->avail; } n = aligned_len >> c->max_write_shift; if (n) { n <<= c->max_write_shift; err = ubifs_leb_write(c, wbuf->lnum, buf + written, wbuf->offs, n); // n > len, read out of bounds less than 8(n-len) bytes } , which can be catched by KASAN: ========================================================= BUG: KASAN: slab-out-of-bounds in ecc_sw_hamming_calculate+0x1dc/0x7d0 Read of size 4 at addr ffff888105594ff8 by task kworker/u8:4/128 Workqueue: writeback wb_workfn (flush-ubifs_0_0) Call Trace: kasan_report.cold+0x81/0x165 nand_write_page_swecc+0xa9/0x160 ubifs_leb_write+0xf2/0x1b0 [ubifs] ubifs_wbuf_write_nolock+0x421/0x12c0 [ubifs] write_head+0xdc/0x1c0 [ubifs] ubifs_jnl_write_inode+0x627/0x960 [ubifs] wb_workfn+0x8af/0xb80 Function ubifs_wbuf_write_nolock() accepts that parameter 'len' is not 8 bytes aligned, the 'len' represents the true length of buf (which is allocated in 'ubifs_jnl_xxx', eg. ubifs_jnl_write_inode), so ubifs_wbuf_write_nolock() must handle the length read from 'buf' carefully to write leb safely. Fetch a reproducer in [Link]. Fixes: 1e51764a3c2ac0 ("UBIFS: add new flash file system") Link: https://bugzilla.kernel.org/show_bug.cgi?id=214785 Reported-by: Chengsong Ke Signed-off-by: Zhihao Cheng Signed-off-by: Richard Weinberger Signed-off-by: Greg Kroah-Hartman

ubifs: setflags: Make dirtied_ino_d 8 bytes aligned

2022-04-08T12:06:48Z

commit 1b83ec057db16b4d0697dc21ef7a9743b6041f72 upstream. Make 'ui->data_len' aligned with 8 bytes before it is assigned to dirtied_ino_d. Since 8871d84c8f8b0c6b("ubifs: convert to fileattr") applied, 'setflags()' only affects regular files and directories, only xattr inode, symlink inode and special inode(pipe/char_dev/block_dev) have none- zero 'ui->data_len' field, so assertion '!(req->dirtied_ino_d & 7)' cannot fail in ubifs_budget_space(). To avoid assertion fails in future evolution(eg. setflags can operate special inodes), it's better to make dirtied_ino_d 8 bytes aligned, after all aligned size is still zero for regular files. Fixes: 1e51764a3c2ac05a ("UBIFS: add new flash file system") Signed-off-by: Zhihao Cheng Signed-off-by: Richard Weinberger Signed-off-by: Greg Kroah-Hartman

ubifs: Rectify space amount budget for mkdir/tmpfile operations

2022-04-08T12:06:48Z

commit a6dab6607d4681d227905d5198710b575dbdb519 upstream. UBIFS should make sure the flash has enough space to store dirty (Data that is newer than disk) data (in memory), space budget is exactly designed to do that. If space budget calculates less data than we need, 'make_reservation()' will do more work(return -ENOSPC if no free space lelf, sometimes we can see "cannot reserve xxx bytes in jhead xxx, error -28" in ubifs error messages) with ubifs inodes locked, which may effect other syscalls. A simple way to decide how much space do we need when make a budget: See how much space is needed by 'make_reservation()' in ubifs_jnl_xxx() function according to corresponding operation. It's better to report ENOSPC in ubifs_budget_space(), as early as we can. Fixes: 474b93704f32163 ("ubifs: Implement O_TMPFILE") Fixes: 1e51764a3c2ac05 ("UBIFS: add new flash file system") Signed-off-by: Zhihao Cheng Signed-off-by: Richard Weinberger Signed-off-by: Greg Kroah-Hartman

ubifs: Fix 'ui->dirty' race between do_tmpfile() and writeback work

2022-04-08T12:06:47Z

commit 60eb3b9c9f11206996f57cb89521824304b305ad upstream. 'ui->dirty' is not protected by 'ui_mutex' in function do_tmpfile() which may race with ubifs_write_inode[wb_workfn] to access/update 'ui->dirty', finally dirty space is released twice. open(O_TMPFILE) wb_workfn do_tmpfile ubifs_budget_space(ino_req = { .dirtied_ino = 1}) d_tmpfile // mark inode(tmpfile) dirty ubifs_jnl_update // without holding tmpfile's ui_mutex mark_inode_clean(ui) if (ui->dirty) ubifs_release_dirty_inode_budget(ui) // release first time ubifs_write_inode mutex_lock(&ui->ui_mutex) ubifs_release_dirty_inode_budget(ui) // release second time mutex_unlock(&ui->ui_mutex) ui->dirty = 0 Run generic/476 can reproduce following message easily (See reproducer in [Link]): UBIFS error (ubi0:0 pid 2578): ubifs_assert_failed [ubifs]: UBIFS assert failed: c->bi.dd_growth >= 0, in fs/ubifs/budget.c:554 UBIFS warning (ubi0:0 pid 2578): ubifs_ro_mode [ubifs]: switched to read-only mode, error -22 Workqueue: writeback wb_workfn (flush-ubifs_0_0) Call Trace: ubifs_ro_mode+0x54/0x60 [ubifs] ubifs_assert_failed+0x4b/0x80 [ubifs] ubifs_release_budget+0x468/0x5a0 [ubifs] ubifs_release_dirty_inode_budget+0x53/0x80 [ubifs] ubifs_write_inode+0x121/0x1f0 [ubifs] ... wb_workfn+0x283/0x7b0 Fix it by holding tmpfile ubifs inode lock during ubifs_jnl_update(). Similar problem exists in whiteout renaming, but previous fix("ubifs: Rename whiteout atomically") has solved the problem. Fixes: 474b93704f32163 ("ubifs: Implement O_TMPFILE") Link: https://bugzilla.kernel.org/show_bug.cgi?id=214765 Signed-off-by: Zhihao Cheng Signed-off-by: Richard Weinberger Signed-off-by: Greg Kroah-Hartman

ubifs: Rename whiteout atomically

2022-04-08T12:06:47Z

commit 278d9a243635f26c05ad95dcf9c5a593b9e04dc6 upstream. Currently, rename whiteout has 3 steps: 1. create tmpfile(which associates old dentry to tmpfile inode) for whiteout, and store tmpfile to disk 2. link whiteout, associate whiteout inode to old dentry agagin and store old dentry, old inode, new dentry on disk 3. writeback dirty whiteout inode to disk Suddenly power-cut or error occurring(eg. ENOSPC returned by budget, memory allocation failure) during above steps may cause kinds of problems: Problem 1: ENOSPC returned by whiteout space budget (before step 2), old dentry will disappear after rename syscall, whiteout file cannot be found either. ls dir // we get file, whiteout rename(dir/file, dir/whiteout, REANME_WHITEOUT) ENOSPC = ubifs_budget_space(&wht_req) // return ls dir // empty (no file, no whiteout) Problem 2: Power-cut happens before step 3, whiteout inode with 'nlink=1' is not stored on disk, whiteout dentry(old dentry) is written on disk, whiteout file is lost on next mount (We get "dead directory entry" after executing 'ls -l' on whiteout file). Now, we use following 3 steps to finish rename whiteout: 1. create an in-mem inode with 'nlink = 1' as whiteout 2. ubifs_jnl_rename (Write on disk to finish associating old dentry to whiteout inode, associating new dentry with old inode) 3. iput(whiteout) Rely writing in-mem inode on disk by ubifs_jnl_rename() to finish rename whiteout, which avoids middle disk state caused by suddenly power-cut and error occurring. Fixes: 9e0a1fff8db56ea ("ubifs: Implement RENAME_WHITEOUT") Signed-off-by: Zhihao Cheng Signed-off-by: Richard Weinberger Signed-off-by: Greg Kroah-Hartman

ubifs: Add missing iput if do_tmpfile() failed in rename whiteout

2022-04-08T12:06:47Z

commit 716b4573026bcbfa7b58ed19fe15554bac66b082 upstream. whiteout inode should be put when do_tmpfile() failed if inode has been initialized. Otherwise we will get following warning during umount: UBIFS error (ubi0:0 pid 1494): ubifs_assert_failed [ubifs]: UBIFS assert failed: c->bi.dd_growth == 0, in fs/ubifs/super.c:1930 VFS: Busy inodes after unmount of ubifs. Self-destruct in 5 seconds. Fixes: 9e0a1fff8db56ea ("ubifs: Implement RENAME_WHITEOUT") Signed-off-by: Zhihao Cheng Suggested-by: Sascha Hauer Signed-off-by: Richard Weinberger Signed-off-by: Greg Kroah-Hartman

ubifs: Fix deadlock in concurrent rename whiteout and inode writeback

2022-04-08T12:06:47Z

commit afd427048047e8efdedab30e8888044e2be5aa9c upstream. Following hung tasks: [ 77.028764] task:kworker/u8:4 state:D stack: 0 pid: 132 [ 77.028820] Call Trace: [ 77.029027] schedule+0x8c/0x1b0 [ 77.029067] mutex_lock+0x50/0x60 [ 77.029074] ubifs_write_inode+0x68/0x1f0 [ubifs] [ 77.029117] __writeback_single_inode+0x43c/0x570 [ 77.029128] writeback_sb_inodes+0x259/0x740 [ 77.029148] wb_writeback+0x107/0x4d0 [ 77.029163] wb_workfn+0x162/0x7b0 [ 92.390442] task:aa state:D stack: 0 pid: 1506 [ 92.390448] Call Trace: [ 92.390458] schedule+0x8c/0x1b0 [ 92.390461] wb_wait_for_completion+0x82/0xd0 [ 92.390469] __writeback_inodes_sb_nr+0xb2/0x110 [ 92.390472] writeback_inodes_sb_nr+0x14/0x20 [ 92.390476] ubifs_budget_space+0x705/0xdd0 [ubifs] [ 92.390503] do_rename.cold+0x7f/0x187 [ubifs] [ 92.390549] ubifs_rename+0x8b/0x180 [ubifs] [ 92.390571] vfs_rename+0xdb2/0x1170 [ 92.390580] do_renameat2+0x554/0x770 , are caused by concurrent rename whiteout and inode writeback processes: rename_whiteout(Thread 1) wb_workfn(Thread2) ubifs_rename do_rename lock_4_inodes (Hold ui_mutex) ubifs_budget_space make_free_space shrink_liability __writeback_inodes_sb_nr bdi_split_work_to_wbs (Queue new wb work) wb_do_writeback(wb work) __writeback_single_inode ubifs_write_inode LOCK(ui_mutex) ↑ wb_wait_for_completion (Wait wb work) <-- deadlock! Reproducer (Detail program in [Link]): 1. SYS_renameat2("/mp/dir/file", "/mp/dir/whiteout", RENAME_WHITEOUT) 2. Consume out of space before kernel(mdelay) doing budget for whiteout Fix it by doing whiteout space budget before locking ubifs inodes. BTW, it also fixes wrong goto tag 'out_release' in whiteout budget error handling path(It should at least recover dir i_size and unlock 4 ubifs inodes). Fixes: 9e0a1fff8db56ea ("ubifs: Implement RENAME_WHITEOUT") Link: https://bugzilla.kernel.org/show_bug.cgi?id=214733 Signed-off-by: Zhihao Cheng Signed-off-by: Richard Weinberger Signed-off-by: Greg Kroah-Hartman

ubifs: rename_whiteout: Fix double free for whiteout_ui->data

2022-04-08T12:06:47Z

commit 40a8f0d5e7b3999f096570edab71c345da812e3e upstream. 'whiteout_ui->data' will be freed twice if space budget fail for rename whiteout operation as following process: rename_whiteout dev = kmalloc whiteout_ui->data = dev kfree(whiteout_ui->data) // Free first time iput(whiteout) ubifs_free_inode kfree(ui->data) // Double free! KASAN reports: ================================================================== BUG: KASAN: double-free or invalid-free in ubifs_free_inode+0x4f/0x70 Call Trace: kfree+0x117/0x490 ubifs_free_inode+0x4f/0x70 [ubifs] i_callback+0x30/0x60 rcu_do_batch+0x366/0xac0 __do_softirq+0x133/0x57f Allocated by task 1506: kmem_cache_alloc_trace+0x3c2/0x7a0 do_rename+0x9b7/0x1150 [ubifs] ubifs_rename+0x106/0x1f0 [ubifs] do_syscall_64+0x35/0x80 Freed by task 1506: kfree+0x117/0x490 do_rename.cold+0x53/0x8a [ubifs] ubifs_rename+0x106/0x1f0 [ubifs] do_syscall_64+0x35/0x80 The buggy address belongs to the object at ffff88810238bed8 which belongs to the cache kmalloc-8 of size 8 ================================================================== Let ubifs_free_inode() free 'whiteout_ui->data'. BTW, delete unused assignment 'whiteout_ui->data_len = 0', process 'ubifs_evict_inode() -> ubifs_jnl_delete_inode() -> ubifs_jnl_write_inode()' doesn't need it (because 'inc_nlink(whiteout)' won't be excuted by 'goto out_release', and the nlink of whiteout inode is 0). Fixes: 9e0a1fff8db56ea ("ubifs: Implement RENAME_WHITEOUT") Signed-off-by: Zhihao Cheng Signed-off-by: Richard Weinberger Signed-off-by: Greg Kroah-Hartman