Bug 2307901 (CVE-2024-44942)

Summary:	CVE-2024-44942 kernel: f2fs: fix to do sanity check on F2FS_INLINE_DATA flag in inode during GC
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	CC:	dfreiber, drow, jburrell, vkumar
Target Milestone:	---	Keywords:	Security
Target Release:	---
Hardware:	All
OS:	Linux
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oVirt Team:	---	RHEL 7.3 requirements from Atomic Host:
Cloudforms Team:	---	Target Upstream Version:
Embargoed:
Bug Depends On:	2308143
Bug Blocks:

Description OSIDB Bzimport 2024-08-26 12:20:45 UTC

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

f2fs: fix to do sanity check on F2FS_INLINE_DATA flag in inode during GC

syzbot reports a f2fs bug as below:

------------[ cut here ]------------
kernel BUG at fs/f2fs/inline.c:258!
CPU: 1 PID: 34 Comm: kworker/u8:2 Not tainted 6.9.0-rc6-syzkaller-00012-g9e4bc4bcae01 #0
RIP: 0010:f2fs_write_inline_data+0x781/0x790 fs/f2fs/inline.c:258
Call Trace:
 f2fs_write_single_data_page+0xb65/0x1d60 fs/f2fs/data.c:2834
 f2fs_write_cache_pages fs/f2fs/data.c:3133 [inline]
 __f2fs_write_data_pages fs/f2fs/data.c:3288 [inline]
 f2fs_write_data_pages+0x1efe/0x3a90 fs/f2fs/data.c:3315
 do_writepages+0x35b/0x870 mm/page-writeback.c:2612
 __writeback_single_inode+0x165/0x10b0 fs/fs-writeback.c:1650
 writeback_sb_inodes+0x905/0x1260 fs/fs-writeback.c:1941
 wb_writeback+0x457/0xce0 fs/fs-writeback.c:2117
 wb_do_writeback fs/fs-writeback.c:2264 [inline]
 wb_workfn+0x410/0x1090 fs/fs-writeback.c:2304
 process_one_work kernel/workqueue.c:3254 [inline]
 process_scheduled_works+0xa12/0x17c0 kernel/workqueue.c:3335
 worker_thread+0x86d/0xd70 kernel/workqueue.c:3416
 kthread+0x2f2/0x390 kernel/kthread.c:388
 ret_from_fork+0x4d/0x80 arch/x86/kernel/process.c:147
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244

The root cause is: inline_data inode can be fuzzed, so that there may
be valid blkaddr in its direct node, once f2fs triggers background GC
to migrate the block, it will hit f2fs_bug_on() during dirty page
writeback.

Let's add sanity check on F2FS_INLINE_DATA flag in inode during GC,
so that, it can forbid migrating inline_data inode's data block for
fixing.

Comment 1 Mauro Matteo Cascella 2024-08-27 12:23:59 UTC

Upstream advisory:
https://lore.kernel.org/linux-cve-announce/2024082620-CVE-2024-44942-651a@gregkh/T