In the Linux kernel, the following vulnerability has been resolved:
usb: gadget: f_fs: Remove WARN_ON in functionfs_bind
This commit addresses an issue related to below kernel panic where
panic_on_warn is enabled. It is caused by the unnecessary use of WARN_ON
in functionsfs_bind, which easily leads to the following scenarios.
1.adb_write in adbd 2. UDC write via configfs
================= =====================
->usb_ffs_open_thread() ->UDC write
->open_functionfs() ->configfs_write_iter()
->adb_open() ->gadget_dev_desc_UDC_store()
->adb_write() ->usb_gadget_register_driver_owner
->driver_register()
->StartMonitor() ->bus_add_driver()
->adb_read() ->gadget_bind_driver()
->configfs_composite_bind()
->usb_add_function()
->open_functionfs() ->ffs_func_bind()
->adb_open() ->functionfs_bind()
state !=FFS_ACTIVE>
The adb_open, adb_read, and adb_write operations are invoked from the
daemon, but trying to bind the function is a process that is invoked by
UDC write through configfs, which opens up the possibility of a race
condition between the two paths. In this race scenario, the kernel panic
occurs due to the WARN_ON from functionfs_bind when panic_on_warn is
enabled. This commit fixes the kernel panic by removing the unnecessary
WARN_ON.
Kernel panic - not syncing: kernel: panic_on_warn set ...
[ 14.542395] Call trace:
[ 14.542464] ffs_func_bind+0x1c8/0x14a8
[ 14.542468] usb_add_function+0xcc/0x1f0
[ 14.542473] configfs_composite_bind+0x468/0x588
[ 14.542478] gadget_bind_driver+0x108/0x27c
[ 14.542483] really_probe+0x190/0x374
[ 14.542488] __driver_probe_device+0xa0/0x12c
[ 14.542492] driver_probe_device+0x3c/0x220
[ 14.542498] __driver_attach+0x11c/0x1fc
[ 14.542502] bus_for_each_dev+0x104/0x160
[ 14.542506] driver_attach+0x24/0x34
[ 14.542510] bus_add_driver+0x154/0x270
[ 14.542514] driver_register+0x68/0x104
[ 14.542518] usb_gadget_register_driver_owner+0x48/0xf4
[ 14.542523] gadget_dev_desc_UDC_store+0xf8/0x144
[ 14.542526] configfs_write_iter+0xf0/0x138
What the EG score is made of (scorer v4.0: the three questions the 0–10 score mixes, published apart · methodology)
The EG score (4.7): severity, escalated by confirmed exploitation. This CVE's 4.7 is its impact severity (EG Severity), not escalated.
- EG Severity
- 4.7 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 every mission impact level.CISA BOD 26-04: 60 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 every mission impact level.
A fix is available. Apply it within your standard update timelines.
Exploitation none (CISA Vulnrichment) · Automatable no (CISA Vulnrichment) · Technical impact partial (CISA Vulnrichment). All three are CISA's SSVC values (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)60 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 Vulnrichment) · Technical impact partial (CISA Vulnrichment). 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