CVE-2023-53537 — f2fs: fix to avoid use-after-free for cached IPU bio

Description

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.

Affected products

Vendor	Product	Affected	Fixed
Linux	Linux	5.5	5.10.180

Fixed in Linux distributions

Distributions backport fixes, so the version that fixes this vulnerability differs per release — upgrade to at least the version shown. From the distributions' security trackers and advisories.

Debian

Security tracker ↗

Release	Package	Fixed in	Advisory
Debian 14	linux	6.3.7-1	—
Debian 13	linux	6.3.7-1	—
Debian 12	linux	6.1.37-1	—

Ubuntu