Bug 2425163 (CVE-2022-50753)

Summary:	CVE-2022-50753 kernel: Linux kernel: F2FS use-after-free vulnerability leading to denial of service or arbitrary code execution
Product:	[Other] Security Response	Reporter:	OSIDB Bzimport <bzimport>
Component:	vulnerability	Assignee:	Product Security DevOps Team <prodsec-dev>
Status:	NEW ---	QA Contact:
Severity:	high	Docs Contact:
Priority:	high
Version:	unspecified	CC:	rhel-process-autobot, watson-tool-maintainers
Target Milestone:	---	Keywords:	Security
Target Release:	---
Hardware:	All
OS:	Linux
Whiteboard:
Fixed In Version:		Doc Type:	---
Doc Text:	A flaw was found in the Linux kernel's F2FS (Flash-Friendly File System) component. A local attacker could exploit a use-after-free vulnerability in the `recover_data` function by mounting a specially crafted F2FS image with a corrupted Summary Segment Area (SSA) table. This out-of-range access could lead to a system crash (denial of service) or potentially arbitrary code execution, compromising the system's integrity and confidentiality.	Story Points:	---
Clone Of:		Environment:
Last Closed:		Type:	---
Regression:	---	Mount Type:	---
Documentation:	---	CRM:
Verified Versions:		Category:	---
oVirt Team:	---	RHEL 7.3 requirements from Atomic Host:
Cloudforms Team:	---	Target Upstream Version:
Embargoed:

Description OSIDB Bzimport 2025-12-24 14:07:43 UTC

In the Linux kernel, the following vulnerability has been resolved:

f2fs: fix to do sanity check on summary info

As Wenqing Liu reported in bugzilla:

https://bugzilla.kernel.org/show_bug.cgi?id=216456

BUG: KASAN: use-after-free in recover_data+0x63ae/0x6ae0 [f2fs]
Read of size 4 at addr ffff8881464dcd80 by task mount/1013

CPU: 3 PID: 1013 Comm: mount Tainted: G        W          6.0.0-rc4 #1
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.15.0-1 04/01/2014
Call Trace:
 dump_stack_lvl+0x45/0x5e
 print_report.cold+0xf3/0x68d
 kasan_report+0xa8/0x130
 recover_data+0x63ae/0x6ae0 [f2fs]
 f2fs_recover_fsync_data+0x120d/0x1fc0 [f2fs]
 f2fs_fill_super+0x4665/0x61e0 [f2fs]
 mount_bdev+0x2cf/0x3b0
 legacy_get_tree+0xed/0x1d0
 vfs_get_tree+0x81/0x2b0
 path_mount+0x47e/0x19d0
 do_mount+0xce/0xf0
 __x64_sys_mount+0x12c/0x1a0
 do_syscall_64+0x38/0x90
 entry_SYSCALL_64_after_hwframe+0x63/0xcd

The root cause is: in fuzzed image, SSA table is corrupted: ofs_in_node
is larger than ADDRS_PER_PAGE(), result in out-of-range access on 4k-size
page.

- recover_data
 - do_recover_data
  - check_index_in_prev_nodes
   - f2fs_data_blkaddr

This patch adds sanity check on summary info in recovery and GC flow
in where the flows rely on them.

After patch:
[   29.310883] F2FS-fs (loop0): Inconsistent ofs_in_node:65286 in summary, ino:0, nid:6, max:1018

Comment 1 Alexander B 2025-12-24 21:58:05 UTC

Upstream advisory:
https://lore.kernel.org/linux-cve-announce/2025122452-CVE-2022-50753-6266@gregkh/T