In the Linux kernel, the following vulnerability has been resolved:
jffs2: check jffs2_prealloc_raw_node_refs() result in few other places
Fuzzing hit another invalid pointer dereference due to the lack of
checking whether jffs2_prealloc_raw_node_refs() completed successfully.
Subsequent logic implies that the node refs have been allocated.
Handle that. The code is ready for propagating the error upwards.
KASAN: null-ptr-deref in range [0x0000000000000008-0x000000000000000f]
CPU: 1 PID: 5835 Comm: syz-executor145 Not tainted 5.10.234-syzkaller #0
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.12.0-1 04/01/2014
RIP: 0010:jffs2_link_node_ref+0xac/0x690 fs/jffs2/nodelist.c:600
Call Trace:
jffs2_mark_erased_block fs/jffs2/erase.c:460 [inline]
jffs2_erase_pending_blocks+0x688/0x1860 fs/jffs2/erase.c:118
jffs2_garbage_collect_pass+0x638/0x1a00 fs/jffs2/gc.c:253
jffs2_reserve_space+0x3f4/0xad0 fs/jffs2/nodemgmt.c:167
jffs2_write_inode_range+0x246/0xb50 fs/jffs2/write.c:362
jffs2_write_end+0x712/0x1110 fs/jffs2/file.c:302
generic_perform_write+0x2c2/0x500 mm/filemap.c:3347
__generic_file_write_iter+0x252/0x610 mm/filemap.c:3465
generic_file_write_iter+0xdb/0x230 mm/filemap.c:3497
call_write_iter include/linux/fs.h:2039 [inline]
do_iter_readv_writev+0x46d/0x750 fs/read_write.c:740
do_iter_write+0x18c/0x710 fs/read_write.c:866
vfs_writev+0x1db/0x6a0 fs/read_write.c:939
do_pwritev fs/read_write.c:1036 [inline]
__do_sys_pwritev fs/read_write.c:1083 [inline]
__se_sys_pwritev fs/read_write.c:1078 [inline]
__x64_sys_pwritev+0x235/0x310 fs/read_write.c:1078
do_syscall_64+0x30/0x40 arch/x86/entry/common.c:46
entry_SYSCALL_64_after_hwframe+0x67/0xd1
Found by Linux Verification Center (linuxtesting.org) with Syzkaller.
What the EG score is made of (scorer v4.0: the three questions the 0–10 score mixes, published apart · methodology)
The EG score (5.5): severity, escalated by confirmed exploitation. This CVE's 5.5 is its impact severity (EG Severity), not escalated.
- EG Severity
- 5.5 MEDIUMCVSS-B, impact only: no KEV listing, EPSS or EG-KEV tier raises it.GitHub Security Advisory CVSS
- EG Likelihood
- 0.2% within 30 daysSource: FIRST EPSS. FIRST's exploitation probability, not an EchelonGraph model.
- Confirmed exploitation
- None on record (CISA KEV, EG-KEV Tier 1)Reported apart from the likelihood: an observed fact, not a probability.
- EG Priority
- SSVC Track at medium mission impactTrack at low or medium mission impact; Track* at high (mission-essential systems).CISA BOD 26-04: 14 days if the affected system is publicly exposed; Fix on system upgrade if it is not.Each input and its source, and whom BOD 26-04 binds: the SSVC and BOD 26-04 blocks below.
SSVC (CISA's decision table, applied by EchelonGraph)Track at low or medium mission impact; Track* at high (mission-essential systems).
A fix is available. Apply it within your standard update timelines.
Exploitation none (no CISA value, KEV listing or exploit code on record) · Automatable no (CISA's BOD 26-04 default) · Technical impact total (CISA's BOD 26-04 default). EchelonGraph holds no SSVC assessment of this CVE from CISA: none of these inputs is from Vulnrichment. EchelonGraph applied CISA's decision table to them; CISA publishes SSVC inputs and the table, not a decision for each CVE. Mission impact is CISA's Mission & Well-being decision point, and only you can judge it. CISA's table makes it high when Mission Prevalence is Essential — the vulnerable component "directly provides capabilities that constitute at least one MEF for at least one entity" (MEF: mission essential function) — or when Public Well-Being Impact is Irreversible: "multiple fatalities are likely", the cyber-physical system "is likely lost or destroyed", "extreme or serious externalities" are imposed on other parties, or social systems such as elections or the financial grid "are destabilized and potentially collapse". CISA's decision table
BOD 26-04 (CISA's remediation timeline, Table 1)14 days if the affected system is publicly exposed; Fix on system upgrade if it is not.
The score's inputs: In CISA KEV no (CISA's KEV catalog) · Automatable no (CISA's BOD 26-04 default) · Technical impact total (CISA's BOD 26-04 default). Where an input reads “CISA's BOD 26-04 default”, no one has published it for this CVE, and CISA's implementation guidance says: “If “Automatable” and “Technical Impact” information items about a CVE ID are not available and the CVE ID is not in the KEV Catalog, CISA will treat its values as “no” and “total,” respectively, until CISA or a third party provides metadata about the CVE ID. CISA will always provide the Vulnrichment data for a CVE ID listed in the KEV Catalog.” Whether your system is publicly exposed is yours to answer. BOD 26-04 binds US Federal Civilian Executive Branch agencies; for anyone else it is CISA's published timeline, a reference rather than an obligation. The directive · how EchelonGraph applies it