# CVE-2022-50009: f2fs: fix null-ptr-deref in f2fs_get_dnode_of_data

CVE-2022-50009 is fixed in linux on 1 platform, first by DEBIAN-CVE-2022-50009, released June 18, 2025. It is not reported as exploited. Patch Radar priority: Routine.

- Web page: https://patchblox.com/security/cve/CVE-2022-50009
- Priority: Routine
- CVSS: 5.5 (Moderate)
- EPSS: 0.0019
- CISA KEV: not listed
- Exploited (vendor report): no
- Publicly disclosed: no
- Published: Jun 18, 2025
- Weakness: NULL Pointer Dereference
- Vendor advisory: https://msrc.microsoft.com/update-guide/vulnerability/CVE-2022-50009

## Description

In the Linux kernel, the following vulnerability has been resolved:  f2fs: fix null-ptr-deref in f2fs_get_dnode_of_data  There is issue as follows when test f2fs atomic write: F2FS-fs (loop0): Can't find valid F2FS filesystem in 2th superblock F2FS-fs (loop0): invalid crc_offset: 0 F2FS-fs (loop0): f2fs_check_nid_range: out-of-range nid=1, run fsck to fix. F2FS-fs (loop0): f2fs_check_nid_range: out-of-range nid=2, run fsck to fix. ================================================================== BUG: KASAN: null-ptr-deref in f2fs_get_dnode_of_data+0xac/0x16d0 Read of size 8 at addr 0000000000000028 by task rep/1990  CPU: 4 PID: 1990 Comm: rep Not tainted 5.19.0-rc6-next-20220715 #266 Call Trace:  <TASK>  dump_stack_lvl+0x6e/0x91  print_report.cold+0x49a/0x6bb  kasan_report+0xa8/0x130  f2fs_get_dnode_of_data+0xac/0x16d0  f2fs_do_write_data_page+0x2a5/0x1030  move_data_page+0x3c5/0xdf0  do_garbage_collect+0x2015/0x36c0  f2fs_gc+0x554/0x1d30  f2fs_balance_fs+0x7f5/0xda0  f2fs_write_single_data_page+0xb66/0xdc0  f2fs_write_cache_pages+0x716/0x1420  f2fs_write_data_pages+0x84f/0x9a0  do_writepages+0x130/0x3a0  filemap_fdatawrite_wbc+0x87/0xa0  file_write_and_wait_range+0x157/0x1c0  f2fs_do_sync_file+0x206/0x12d0  f2fs_sync_file+0x99/0xc0  vfs_fsync_range+0x75/0x140  f2fs_file_write_iter+0xd7b/0x1850  vfs_write+0x645/0x780  ksys_write+0xf1/0x1e0  do_syscall_64+0x3b/0x90  entry_SYSCALL_64_after_hwframe+0x63/0xcd  As 3db1de0e582c commit changed atomic write way which new a cow_inode for atomic write file, and also mark cow_inode as FI_ATOMIC_FILE. When f2fs_do_write_data_page write cow_inode will use cow_inode's cow_inode which is NULL. Then will trigger null-ptr-deref. To solve above issue, introduce FI_COW_FILE flag for COW inode.  Fiexes: 3db1de0e582c("f2fs: change the current atomic write way")

## Where it's fixed

| Platform | Product | Fixed in | Fix | Released |
|---|---|---|---|---|
| Linux | linux Debian 12.15 (bookworm) | 5.19.6-1 | [DEBIAN-CVE-2022-50009](https://patchblox.com/security/data/fix/linux/debian-cve-2022-50009.md) | Jun 18, 2025 |
| Linux | linux Debian 13.5 (trixie) | 5.19.6-1 | [DEBIAN-CVE-2022-50009](https://patchblox.com/security/data/fix/linux/debian-cve-2022-50009.md) | Jun 18, 2025 |
| Linux | linux Debian 14 | 5.19.6-1 | [DEBIAN-CVE-2022-50009](https://patchblox.com/security/data/fix/linux/debian-cve-2022-50009.md) | Jun 18, 2025 |

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