kernel/linux.git/fs/f2fs/data.c, branch v5.15.219

f2fs: fix UAF issue in f2fs_merge_page_bio()

2026-08-23T12:17:14+00:00

commit edf7e9040fc52c922db947f9c6c36f07377c52ea upstream. As JY reported in bugzilla [1], Unable to handle kernel NULL pointer dereference at virtual address 0000000000000000 pc : [0xffffffe51d249484] f2fs_is_cp_guaranteed+0x70/0x98 lr : [0xffffffe51d24adbc] f2fs_merge_page_bio+0x520/0x6d4 CPU: 3 UID: 0 PID: 6790 Comm: kworker/u16:3 Tainted: P B W OE 6.12.30-android16-5-maybe-dirty-4k #1 5f7701c9cbf727d1eebe77c89bbbeb3371e895e5 Tainted: [P]=PROPRIETARY_MODULE, [B]=BAD_PAGE, [W]=WARN, [O]=OOT_MODULE, [E]=UNSIGNED_MODULE Workqueue: writeback wb_workfn (flush-254:49) Call trace: f2fs_is_cp_guaranteed+0x70/0x98 f2fs_inplace_write_data+0x174/0x2f4 f2fs_do_write_data_page+0x214/0x81c f2fs_write_single_data_page+0x28c/0x764 f2fs_write_data_pages+0x78c/0xce4 do_writepages+0xe8/0x2fc __writeback_single_inode+0x4c/0x4b4 writeback_sb_inodes+0x314/0x540 __writeback_inodes_wb+0xa4/0xf4 wb_writeback+0x160/0x448 wb_workfn+0x2f0/0x5dc process_scheduled_works+0x1c8/0x458 worker_thread+0x334/0x3f0 kthread+0x118/0x1ac ret_from_fork+0x10/0x20 [1] https://bugzilla.kernel.org/show_bug.cgi?id=220575 The panic was caused by UAF issue w/ below race condition: kworker - writepages - f2fs_write_cache_pages - f2fs_write_single_data_page - f2fs_do_write_data_page - f2fs_inplace_write_data - f2fs_merge_page_bio - add_inu_page : cache page #1 into bio & cache bio in io->bio_list - f2fs_write_single_data_page - f2fs_do_write_data_page - f2fs_inplace_write_data - f2fs_merge_page_bio - add_inu_page : cache page #2 into bio which is linked in io->bio_list write - f2fs_write_begin : write page #1 - f2fs_folio_wait_writeback - f2fs_submit_merged_ipu_write - f2fs_submit_write_bio : submit bio which inclues page #1 and #2 software IRQ - f2fs_write_end_io - fscrypt_free_bounce_page : freed bounced page which belongs to page #2 - inc_page_count( , WB_DATA_TYPE(data_folio), false) : data_folio points to fio->encrypted_page the bounced page can be freed before accessing it in f2fs_is_cp_guarantee() It can reproduce w/ below testcase: Run below script in shell #1: for ((i=1;i>0;i++)) do xfs_io -f /mnt/f2fs/enc/file \ -c "pwrite 0 32k" -c "fdatasync" Run below script in shell #2: for ((i=1;i>0;i++)) do xfs_io -f /mnt/f2fs/enc/file \ -c "pwrite 0 32k" -c "fdatasync" So, in f2fs_merge_page_bio(), let's avoid using fio->encrypted_page after commit page into internal ipu cache. Fixes: 0b20fcec8651 ("f2fs: cache global IPU bio") Reported-by: JY Signed-off-by: Chao Yu Signed-off-by: Jaegeuk Kim [Jiucheng Xu: backport to 5.15.y] Signed-off-by: Jiucheng Xu Signed-off-by: Sasha Levin

f2fs: fix potential deadlock in f2fs_balance_fs()

2026-07-24T13:51:17+00:00

[ Upstream commit dd3114870771562036fdcf5abe813956f36d224d ] When the f2fs filesystem space is nearly exhausted, we encounter deadlock issues as below: INFO: task A:1890 blocked for more than 120 seconds. Tainted: G O 6.12.41-g3fe07ddf05ab #1 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. task:A state:D stack:0 pid:1890 tgid:1626 ppid:1153 flags:0x00000204 Call trace: __switch_to+0xf4/0x158 __schedule+0x27c/0x908 schedule+0x3c/0x118 io_schedule+0x44/0x68 folio_wait_bit_common+0x174/0x370 folio_wait_bit+0x20/0x38 folio_wait_writeback+0x54/0xc8 truncate_inode_partial_folio+0x70/0x1e0 truncate_inode_pages_range+0x1b0/0x450 truncate_pagecache+0x54/0x88 f2fs_file_write_iter+0x3e8/0xb80 do_iter_readv_writev+0xf0/0x1e0 vfs_writev+0x138/0x2c8 do_writev+0x88/0x130 __arm64_sys_writev+0x28/0x40 invoke_syscall+0x50/0x120 el0_svc_common.constprop.0+0xc8/0xf0 do_el0_svc+0x24/0x38 el0_svc+0x30/0xf8 el0t_64_sync_handler+0x120/0x130 el0t_64_sync+0x190/0x198 INFO: task kworker/u8:11:2680853 blocked for more than 120 seconds. Tainted: G O 6.12.41-g3fe07ddf05ab #1 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. task:kworker/u8:11 state:D stack:0 pid:2680853 tgid:2680853 ppid:2 flags:0x00000208 Workqueue: writeback wb_workfn (flush-254:0) Call trace: __switch_to+0xf4/0x158 __schedule+0x27c/0x908 schedule+0x3c/0x118 io_schedule+0x44/0x68 folio_wait_bit_common+0x174/0x370 __filemap_get_folio+0x214/0x348 pagecache_get_page+0x20/0x70 f2fs_get_read_data_page+0x150/0x3e8 f2fs_get_lock_data_page+0x2c/0x160 move_data_page+0x50/0x478 do_garbage_collect+0xd38/0x1528 f2fs_gc+0x240/0x7e0 f2fs_balance_fs+0x1a0/0x208 f2fs_write_single_data_page+0x6e4/0x730 f2fs_write_cache_pages+0x378/0x9b0 f2fs_write_data_pages+0x2e4/0x388 do_writepages+0x8c/0x2c8 __writeback_single_inode+0x4c/0x498 writeback_sb_inodes+0x234/0x4a8 __writeback_inodes_wb+0x58/0x118 wb_writeback+0x2f8/0x3c0 wb_workfn+0x2c4/0x508 process_one_work+0x180/0x408 worker_thread+0x258/0x368 kthread+0x118/0x128 ret_from_fork+0x10/0x200 INFO: task kworker/u8:8:2641297 blocked for more than 120 seconds. Tainted: G O 6.12.41-g3fe07ddf05ab #1 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. task:kworker/u8:8 state:D stack:0 pid:2641297 tgid:2641297 ppid:2 flags:0x00000208 Workqueue: writeback wb_workfn (flush-254:0) Call trace: __switch_to+0xf4/0x158 __schedule+0x27c/0x908 rt_mutex_schedule+0x30/0x60 __rt_mutex_slowlock_locked.constprop.0+0x460/0x8a8 rwbase_write_lock+0x24c/0x378 down_write+0x1c/0x30 f2fs_balance_fs+0x184/0x208 f2fs_write_inode+0xf4/0x328 __writeback_single_inode+0x370/0x498 writeback_sb_inodes+0x234/0x4a8 __writeback_inodes_wb+0x58/0x118 wb_writeback+0x2f8/0x3c0 wb_workfn+0x2c4/0x508 process_one_work+0x180/0x408 worker_thread+0x258/0x368 kthread+0x118/0x128 ret_from_fork+0x10/0x20 INFO: task B:1902 blocked for more than 120 seconds. Tainted: G O 6.12.41-g3fe07ddf05ab #1 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. task:B state:D stack:0 pid:1902 tgid:1626 ppid:1153 flags:0x0000020c Call trace: __switch_to+0xf4/0x158 __schedule+0x27c/0x908 rt_mutex_schedule+0x30/0x60 __rt_mutex_slowlock_locked.constprop.0+0x460/0x8a8 rwbase_write_lock+0x24c/0x378 down_write+0x1c/0x30 f2fs_balance_fs+0x184/0x208 f2fs_map_blocks+0x94c/0x1110 f2fs_file_write_iter+0x228/0xb80 do_iter_readv_writev+0xf0/0x1e0 vfs_writev+0x138/0x2c8 do_writev+0x88/0x130 __arm64_sys_writev+0x28/0x40 invoke_syscall+0x50/0x120 el0_svc_common.constprop.0+0xc8/0xf0 do_el0_svc+0x24/0x38 el0_svc+0x30/0xf8 el0t_64_sync_handler+0x120/0x130 el0t_64_sync+0x190/0x198 INFO: task sync:2769849 blocked for more than 120 seconds. Tainted: G O 6.12.41-g3fe07ddf05ab #1 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. task:sync state:D stack:0 pid:2769849 tgid:2769849 ppid:736 flags:0x0000020c Call trace: __switch_to+0xf4/0x158 __schedule+0x27c/0x908 schedule+0x3c/0x118 wb_wait_for_completion+0xb0/0xe8 sync_inodes_sb+0xc8/0x2b0 sync_inodes_one_sb+0x24/0x38 iterate_supers+0xa8/0x138 ksys_sync+0x54/0xc8 __arm64_sys_sync+0x18/0x30 invoke_syscall+0x50/0x120 el0_svc_common.constprop.0+0xc8/0xf0 do_el0_svc+0x24/0x38 el0_svc+0x30/0xf8 el0t_64_sync_handler+0x120/0x130 el0t_64_sync+0x190/0x198 The root cause is a potential deadlock between the following tasks: kworker/u8:11 Thread A - f2fs_write_single_data_page - f2fs_do_write_data_page - folio_start_writeback(X) - f2fs_outplace_write_data - bio_add_folio(X) - folio_unlock(X) - truncate_inode_pages_range - __filemap_get_folio(X, FGP_LOCK) - truncate_inode_partial_folio(X) - folio_wait_writeback(X) - f2fs_balance_fs - f2fs_gc - do_garbage_collect - move_data_page - f2fs_get_lock_data_page - __filemap_get_folio(X, FGP_LOCK) Both threads try to access folio X. Thread A holds the lock but waits for writeback, while kworker waits for the lock. This causes a deadlock. Other threads also enter D state, waiting for locks such as gc_lock and writepages. OPU/IPU DATA folio are all affected by this issue. To avoid such potential deadlocks, always commit these cached folios before triggering f2fs_gc() in f2fs_balance_fs(). Suggested-by: Chao Yu Reviewed-by: Chao Yu Signed-off-by: Ruipeng Qi Signed-off-by: Jaegeuk Kim Stable-dep-of: 8b4468ec023d ("f2fs: fix potential deadlock in gc_merge path of f2fs_balance_fs()") Signed-off-by: Sasha Levin Signed-off-by: Greg Kroah-Hartman

f2fs: fix UAF caused by decrementing sbi->nr_pages[] in f2fs_write_end_io()

2026-06-19T11:33:40+00:00

[ Upstream commit 2d9c4a4ed4eef1f82c5b16b037aee8bad819fd53 ] The xfstests case "generic/107" and syzbot have both reported a NULL pointer dereference. The concurrent scenario that triggers the panic is as follows: F2FS_WB_CP_DATA write callback umount - f2fs_write_checkpoint - f2fs_wait_on_all_pages(sbi, F2FS_WB_CP_DATA) - blk_mq_end_request - bio_endio - f2fs_write_end_io : dec_page_count(sbi, F2FS_WB_CP_DATA) : wake_up(&sbi->cp_wait) - kill_f2fs_super - kill_block_super - f2fs_put_super : iput(sbi->node_inode) : sbi->node_inode = NULL : f2fs_in_warm_node_list - is_node_folio // sbi->node_inode is NULL and panic The root cause is that f2fs_put_super() calls iput(sbi->node_inode) and sets sbi->node_inode to NULL after sbi->nr_pages[F2FS_WB_CP_DATA] is decremented to zero. As a result, f2fs_in_warm_node_list() may dereference a NULL node_inode when checking whether a folio belongs to the node inode, leading to a panic. This patch fixes the issue by calling f2fs_in_warm_node_list() before decrementing sbi->nr_pages[F2FS_WB_CP_DATA], thus preventing the use-after-free condition. Cc: stable@kernel.org Fixes: 50fa53eccf9f ("f2fs: fix to avoid broken of dnode block list") Reported-by: syzbot+6e4cb1cac5efc96ea0ca@syzkaller.appspotmail.com Signed-off-by: Yongpeng Yang Reviewed-by: Chao Yu Signed-off-by: Jaegeuk Kim [ folio => page ] Signed-off-by: Sasha Levin Signed-off-by: Greg Kroah-Hartman

f2fs: fix to trigger foreground gc during f2fs_map_blocks() in lfs mode

2026-06-01T15:35:11+00:00

[ Upstream commit 1005a3ca28e90c7a64fa43023f866b960a60f791 ] w/ "mode=lfs" mount option, generic/299 will cause system panic as below: ------------[ cut here ]------------ kernel BUG at fs/f2fs/segment.c:2835! Call Trace: f2fs_allocate_data_block+0x6f4/0xc50 f2fs_map_blocks+0x970/0x1550 f2fs_iomap_begin+0xb2/0x1e0 iomap_iter+0x1d6/0x430 __iomap_dio_rw+0x208/0x9a0 f2fs_file_write_iter+0x6b3/0xfa0 aio_write+0x15d/0x2e0 io_submit_one+0x55e/0xab0 __x64_sys_io_submit+0xa5/0x230 do_syscall_64+0x84/0x2f0 entry_SYSCALL_64_after_hwframe+0x76/0x7e RIP: 0010:new_curseg+0x70f/0x720 The root cause of we run out-of-space is: in f2fs_map_blocks(), f2fs may trigger foreground gc only if it allocates any physical block, it will be a little bit later when there is multiple threads writing data w/ aio/dio/bufio method in parallel, since we always use OPU in lfs mode, so f2fs_map_blocks() does block allocations aggressively. In order to fix this issue, let's give a chance to trigger foreground gc in prior to block allocation in f2fs_map_blocks(). Fixes: 36abef4e796d ("f2fs: introduce mode=lfs mount option") Cc: Daeho Jeong Signed-off-by: Chao Yu Signed-off-by: Jaegeuk Kim [ The context change is due to the commit 2f51ade9524c ("f2fs: f2fs_do_map_lock") in v6.3 which is irrelevant to the logic of this patch. ] Signed-off-by: Rahul Sharma Signed-off-by: Greg Kroah-Hartman

f2fs: fix to wait on block writeback for post_read case

2026-06-01T15:35:10+00:00

[ Upstream commit 55fdc1c24a1d6229fe0ecf31335fb9a2eceaaa00 ] If inode is compressed, but not encrypted, it missed to call f2fs_wait_on_block_writeback() to wait for GCed page writeback in IPU write path. Thread A GC-Thread - f2fs_gc - do_garbage_collect - gc_data_segment - move_data_block - f2fs_submit_page_write migrate normal cluster's block via meta_inode's page cache - f2fs_write_single_data_page - f2fs_do_write_data_page - f2fs_inplace_write_data - f2fs_submit_page_bio IRQ - f2fs_read_end_io IRQ old data overrides new data due to out-of-order GC and common IO. - f2fs_read_end_io Fixes: 4c8ff7095bef ("f2fs: support data compression") Signed-off-by: Chao Yu Signed-off-by: Jaegeuk Kim [ Minor context change fixed. ] Signed-off-by: Robert Garcia Signed-off-by: Greg Kroah-Hartman

f2fs: fix to avoid UAF in f2fs_write_end_io()

2026-02-19T15:21:47+00:00

[ Upstream commit ce2739e482bce8d2c014d76c4531c877f382aa54 ] As syzbot reported an use-after-free issue in f2fs_write_end_io(). It is caused by below race condition: loop device umount - worker_thread - loop_process_work - do_req_filebacked - lo_rw_aio - lo_rw_aio_complete - blk_mq_end_request - blk_update_request - f2fs_write_end_io - dec_page_count - folio_end_writeback - kill_f2fs_super - kill_block_super - f2fs_put_super : free(sbi) : get_pages(, F2FS_WB_CP_DATA) accessed sbi which is freed In kill_f2fs_super(), we will drop all page caches of f2fs inodes before call free(sbi), it guarantee that all folios should end its writeback, so it should be safe to access sbi before last folio_end_writeback(). Let's relocate ckpt thread wakeup flow before folio_end_writeback() to resolve this issue. Cc: stable@kernel.org Fixes: e234088758fc ("f2fs: avoid wait if IO end up when do_checkpoint for better performance") Reported-by: syzbot+b4444e3c972a7a124187@syzkaller.appspotmail.com Closes: https://syzkaller.appspot.com/bug?extid=b4444e3c972a7a124187 Signed-off-by: Chao Yu Signed-off-by: Jaegeuk Kim [ folio => page ] Signed-off-by: Sasha Levin Signed-off-by: Greg Kroah-Hartman

f2fs: fix wrong block mapping for multi-devices

2025-10-29T13:03:15+00:00

[ Upstream commit 9d5c4f5c7a2c7677e1b3942772122b032c265aae ] Assuming the disk layout as below, disk0: 0 --- 0x00035abfff disk1: 0x00035ac000 --- 0x00037abfff disk2: 0x00037ac000 --- 0x00037ebfff and we want to read data from offset=13568 having len=128 across the block devices, we can illustrate the block addresses like below. 0 .. 0x00037ac000 ------------------- 0x00037ebfff, 0x00037ec000 ------- | ^ ^ ^ | fofs 0 13568 13568+128 | ------------------------------------------------------ | LBA 0x37e8aa9 0x37ebfa9 0x37ec029 --- map 0x3caa9 0x3ffa9 In this example, we should give the relative map of the target block device ranging from 0x3caa9 to 0x3ffa9 where the length should be calculated by 0x37ebfff + 1 - 0x37ebfa9. In the below equation, however, map->m_pblk was supposed to be the original address instead of the one from the target block address. - map->m_len = min(map->m_len, dev->end_blk + 1 - map->m_pblk); Cc: stable@vger.kernel.org Fixes: 71f2c8206202 ("f2fs: multidevice: support direct IO") Reviewed-by: Chao Yu Signed-off-by: Jaegeuk Kim [ applied fix to f2fs_map_blocks() instead of f2fs_map_blocks_cached() ] Signed-off-by: Sasha Levin Signed-off-by: Greg Kroah-Hartman

f2fs: fix to detect gcing page in f2fs_is_cp_guaranteed()

2025-06-27T10:05:12+00:00

[ Upstream commit aa1be8dd64163eca4dde7fd2557eb19927a06a47 ] Jan Prusakowski reported a f2fs bug as below: f2fs/007 will hang kernel during testing w/ below configs: kernel 6.12.18 (from pixel-kernel/android16-6.12) export MKFS_OPTIONS="-O encrypt -O extra_attr -O project_quota -O quota" export F2FS_MOUNT_OPTIONS="test_dummy_encryption,discard,fsync_mode=nobarrier,reserve_root=32768,checkpoint_merge,atgc" cat /proc//stack f2fs_wait_on_all_pages+0xa3/0x130 do_checkpoint+0x40c/0x5d0 f2fs_write_checkpoint+0x258/0x550 kill_f2fs_super+0x14f/0x190 deactivate_locked_super+0x30/0xb0 cleanup_mnt+0xba/0x150 task_work_run+0x59/0xa0 syscall_exit_to_user_mode+0x12d/0x130 do_syscall_64+0x57/0x110 entry_SYSCALL_64_after_hwframe+0x76/0x7e cat /sys/kernel/debug/f2fs/status - IO_W (CP: -256, Data: 256, Flush: ( 0 0 1), Discard: ( 0 0)) cmd: 0 undiscard: 0 CP IOs reference count becomes negative. The root cause is: After 4961acdd65c9 ("f2fs: fix to tag gcing flag on page during block migration"), we will tag page w/ gcing flag for raw page of cluster during its migration. However, if the inode is both encrypted and compressed, during ioc_decompress(), it will tag page w/ gcing flag, and it increase F2FS_WB_DATA reference count: - f2fs_write_multi_page - f2fs_write_raw_page - f2fs_write_single_page - do_write_page - f2fs_submit_page_write - WB_DATA_TYPE(bio_page, fio->compressed_page) : bio_page is encrypted, so mapping is NULL, and fio->compressed_page is NULL, it returns F2FS_WB_DATA - inc_page_count(.., F2FS_WB_DATA) Then, during end_io(), it decrease F2FS_WB_CP_DATA reference count: - f2fs_write_end_io - f2fs_compress_write_end_io - fscrypt_pagecache_folio : get raw page from encrypted page - WB_DATA_TYPE(&folio->page, false) : raw page has gcing flag, it returns F2FS_WB_CP_DATA - dec_page_count(.., F2FS_WB_CP_DATA) In order to fix this issue, we need to detect gcing flag in raw page in f2fs_is_cp_guaranteed(). Fixes: 4961acdd65c9 ("f2fs: fix to tag gcing flag on page during block migration") Reported-by: Jan Prusakowski Signed-off-by: Chao Yu Signed-off-by: Jaegeuk Kim Signed-off-by: Sasha Levin

f2fs: clean up w/ fscrypt_is_bounce_page()

2025-06-27T10:05:12+00:00

[ Upstream commit 0c708e35cf26449ca317fcbfc274704660b6d269 ] Just cleanup, no logic changes. Signed-off-by: Chao Yu Signed-off-by: Jaegeuk Kim Signed-off-by: Sasha Levin

f2fs: introduce F2FS_IPU_HONOR_OPU_WRITE ipu policy

2024-10-17T13:11:05+00:00

[ Upstream commit 1018a5463a063715365784704c4e8cdf2eec4b04 ] Once F2FS_IPU_FORCE policy is enabled in some cases: a) f2fs forces to use F2FS_IPU_FORCE in a small-sized volume b) user sets F2FS_IPU_FORCE policy via sysfs Then we may fail to defragment file due to IPU policy check, it doesn't make sense, let's introduce a new IPU policy to allow OPU during file defragmentation. In small-sized volume, let's enable F2FS_IPU_HONOR_OPU_WRITE policy by default. Signed-off-by: Chao Yu Signed-off-by: Jaegeuk Kim Stable-dep-of: 884ee6dc85b9 ("f2fs: get rid of online repaire on corrupted directory") Signed-off-by: Sasha Levin