Bug 2401562 (CVE-2023-53537)

Summary:	CVE-2023-53537 kernel: f2fs: fix to avoid use-after-free for cached IPU bio
Product:	[Other] Security Response	Reporter:	OSIDB Bzimport <bzimport>
Component:	vulnerability	Assignee:	Product Security DevOps Team <prodsec-dev>
Status:	NEW ---	QA Contact:
Severity:	medium	Docs Contact:
Priority:	medium
Version:	unspecified	Keywords:	Security
Target Milestone:	---
Target Release:	---
Hardware:	All
OS:	Linux
Whiteboard:
Fixed In Version:		Doc Type:	---
Doc Text:	A use-after-free flaw was found in the Linux kernel's F2FS filesystem in the cached IPU (In-Place Update) bio handling. A local user can trigger this issue when checkpoint errors occur during writeback, causing f2fs_submit_merged_ipu_write to submit a stale cached bio pointer that belongs to a different IO context. This results in using freed memory, triggering kernel bugs in page writeback completion, and causing denial of service through kernel crashes.	Story Points:	---
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oVirt Team:	---	RHEL 7.3 requirements from Atomic Host:
Cloudforms Team:	---	Target Upstream Version:
Embargoed:

Description OSIDB Bzimport 2025-10-04 16:07:35 UTC

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

f2fs: fix to avoid use-after-free for cached IPU bio

xfstest generic/019 reports a bug:

kernel BUG at mm/filemap.c:1619!
RIP: 0010:folio_end_writeback+0x8a/0x90
Call Trace:
 end_page_writeback+0x1c/0x60
 f2fs_write_end_io+0x199/0x420
 bio_endio+0x104/0x180
 submit_bio_noacct+0xa5/0x510
 submit_bio+0x48/0x80
 f2fs_submit_write_bio+0x35/0x300
 f2fs_submit_merged_ipu_write+0x2a0/0x2b0
 f2fs_write_single_data_page+0x838/0x8b0
 f2fs_write_cache_pages+0x379/0xa30
 f2fs_write_data_pages+0x30c/0x340
 do_writepages+0xd8/0x1b0
 __writeback_single_inode+0x44/0x370
 writeback_sb_inodes+0x233/0x4d0
 __writeback_inodes_wb+0x56/0xf0
 wb_writeback+0x1dd/0x2d0
 wb_workfn+0x367/0x4a0
 process_one_work+0x21d/0x430
 worker_thread+0x4e/0x3c0
 kthread+0x103/0x130
 ret_from_fork+0x2c/0x50

The root cause is: after cp_error is set, f2fs_submit_merged_ipu_write()
in f2fs_write_single_data_page() tries to flush IPU bio in cache, however
f2fs_submit_merged_ipu_write() missed to check validity of @bio parameter,
result in submitting random cached bio which belong to other IO context,
then it will cause use-after-free issue, fix it by adding additional
validity check.

Comment 1 Alexander B 2025-10-06 11:47:21 UTC

Upstream advisory:
https://lore.kernel.org/linux-cve-announce/2025100443-CVE-2023-53537-7d50@gregkh/T