usb: gadget: f_fs: Prevent deadlock during ep0 read loop
In the Linux kernel, the following vulnerability has been resolved: usb: gadget: f_fs: Prevent deadlock during ep0 read loop Currently, ffs_ep0_read() holds ffs->mutex when it prepares to go to sleep waiting for an event. When no setup events are pending, it calls wait_event_interruptible_exclusive_locked_irq() with the mutex still held. The wait macro deliberately drops the waitqueue spinlock before sleeping but does not drop the mutex. If a userspace daemon is polling ep0 via read() and the gadget is asynchronously torn down via configfs (e.g., echo "" > UDC), a deadlock can occur: 1. The configfs teardown calls functionfs_unbind(), which queues a FUNCTIONFS_UNBIND event. 2. The daemon wakes up, consumes the event, and drops the mutex. 3. However, if the daemon loops and immediately issues another read() before exiting, it reacquires ffs->mutex and again goes into an interruptible sleep. 4. Meanwhile, functionfs_unbind() continues execution and attempts to acquire ffs->mutex to tear down ep0req. 5. The kernel deadlocks because the configfs thread is stuck in an uninterruptible sleep waiting for the mutex, while the userspace daemon is in an interruptible sleep holding the mutex forever because no more events will arrive. To fix this, we drop both the waitqueue spinlock and ffs->mutex before going to sleep, and use wait_event_interruptible_exclusive() instead. Upon waking up, we jump back to the `retry` label to safely reacquire the mutex and re-evaluate the state machine. By not sleeping with ffs->mutex held, we natively decouple gadget teardowns (which require the mutex) from userspace polling.
- Published
- Sep 11, 2026
- Updated
- Sep 14, 2026
- EPSS
- 0.2% · 13th percentile
- CWE
- —
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Report tools
Action score
0
Monitor
Low priority for now.
- CVSS
- 0 / 40 · —
- CISA KEV
- 0 / 30 · Not listed
- EPSS
- 0 / 30 · 0.2%
Noroxi analysis
No Noroxi analysis for this record yet
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We use this product, ask for helpAffected systems
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Versions reported by the vendor
Affected version ranges reported by the assigning authority (Linux). Independent of NVD's CPE analysis and usually ahead of it.
Linux Linux
- 2.6.35affected
- ddf8abd2599491cbad959c700b90ba72a5dce8d0 and later · before fbe3db4b650c284df8eb4cb68eebcf270cf861b5affected · git
- ddf8abd2599491cbad959c700b90ba72a5dce8d0 and later · before 30430509c156e1df2bdafd5f1cadb160e53db5d6affected · git
- ddf8abd2599491cbad959c700b90ba72a5dce8d0 and later · before bafddd0f20b5228760be303aa69c58502e92309caffected · git
- ddf8abd2599491cbad959c700b90ba72a5dce8d0 and later · before b0a6bfac0c3c3edf5b2ecaee87a09234601fe78daffected · git
- ddf8abd2599491cbad959c700b90ba72a5dce8d0 and later · before fd20cc68bbdb5620696ac108e8f2efd180fe2c1aaffected · git
- ddf8abd2599491cbad959c700b90ba72a5dce8d0 and later · before 34e88f53614640b59039a46717fb6142e9871022affected · git
- ddf8abd2599491cbad959c700b90ba72a5dce8d0 and later · before eac233e63f9db82ba874e3cccafaafab162999e0affected · git
- ddf8abd2599491cbad959c700b90ba72a5dce8d0 and later · before 569dd7e5dcffe1e1c6b26ca2cd3be57eb433e082affected · git
- before 2.6.35not affected · semver
Package-level exposure
OSV and GitHub Advisory data: ecosystem, package and range. SBOM matching uses this table.
| Ecosystem | Package | Affected range | Fix |
|---|---|---|---|
| Debian:12 | linux | all versions | — |
| Debian:13 | linux | before 6.12.111-1 | 6.12.111-1 |
| Debian:14 | linux | before 7.2.6-1 | 7.2.6-1 |
Same product
linux: all recordsOther highest-scoring records for the same primary product.
- CVE-2026-74705udp: fix potential use-after-free in tunnel segmentation40Plan
- CVE-2026-74612veth: fix skb length accounting after XDP frag adjustment40Plan
- CVE-2026-74475vxlan: use neigh_ha_snapshot() in route_shortcircuit()40Plan
- CVE-2026-74309vdpa/octeon_ep: fix IRQ-to-ring mapping in interrupt handler40Plan
- CVE-2026-74280crypto: marvell/octeontx - fix DMA cleanup using wrong loop index40Plan
- CVE-2026-74279crypto: cavium/cpt - fix DMA cleanup using wrong loop index40Plan
Remediation
Which version to upgrade to
Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.
| Product / package | Fixed version | Source |
|---|---|---|
| Linux Linux | 30430509c156e1df2bdafd5f1cadb160e53db5d6 | Vendor (CNA) |
| Linux Linux | 34e88f53614640b59039a46717fb6142e9871022 | Vendor (CNA) |
| Linux Linux | 569dd7e5dcffe1e1c6b26ca2cd3be57eb433e082 | Vendor (CNA) |
| Linux Linux | b0a6bfac0c3c3edf5b2ecaee87a09234601fe78d | Vendor (CNA) |
| Linux Linux | bafddd0f20b5228760be303aa69c58502e92309c | Vendor (CNA) |
| Linux Linux | eac233e63f9db82ba874e3cccafaafab162999e0 | Vendor (CNA) |
| Linux Linux | fbe3db4b650c284df8eb4cb68eebcf270cf861b5 | Vendor (CNA) |
| Linux Linux | fd20cc68bbdb5620696ac108e8f2efd180fe2c1a | Vendor (CNA) |
| debian:linux | 6.12.111-1 · Debian:13 | Package registry (OSV) |
Exploit status
No known public exploit
No public exploit has been observed yet. That doesn't mean you're safe, only that the bar is a little higher.
Research context
For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.
Timeline
From publication to today: proof of concept, Metasploit module, CISA KEV and fix record. Dates are as reported by the sources.
No dated events beyond publication.
FIRST EPSS daily score; only changes of 0.01 or more are recorded (step chart).
Patch and commit links
Commit, PR and diff links among the references. A starting point for patch-diffing and variant hunting; fixes, not exploits.
No commit or PR link among the references.
Credits
All researchersFinders, reporters and analysts named in the CNA record. Click a name for that researcher’s other records.
No credits in the CNA record.
Variant candidates
Same product, same weakness class, within 18 months. If the patch missed the root cause, the sibling bug is here.
No nightly-computed relations.
Chain candidates
An authentication bypass and a privilege-requiring bug in the same product, published close together: combined they may become an unauthenticated path.
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Bug bounty scope
No known public program.
Source: bounty-targets-data (public HackerOne, Bugcrowd, Intigriti, YesWeHack listings).
National notice (Türkiye Cybersecurity Directorate / USOM)
Official security notices citing this record; remediation advice is on the agency's page.
- TR-26-1085 · Sep 14, 2026(Linux Kernel Güvenlik Bildirimi)
Technical details
No CVSS vector for this record, so attack conditions can't be derived.
Weakness class (CWE)
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Attack context
MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.
MITRE has no CAPEC/ATT&CK mapping for this CWE.
Change log
- Fix✗ → ✓
For records you follow, these changes also arrive as notifications. →
References
- git.kernel.org/stable/c/30430509c156e1df2bdafd5f1cadb160e53db5d6
- git.kernel.org/stable/c/34e88f53614640b59039a46717fb6142e9871022
- git.kernel.org/stable/c/569dd7e5dcffe1e1c6b26ca2cd3be57eb433e082
- git.kernel.org/stable/c/b0a6bfac0c3c3edf5b2ecaee87a09234601fe78d
- git.kernel.org/stable/c/bafddd0f20b5228760be303aa69c58502e92309c
- git.kernel.org/stable/c/eac233e63f9db82ba874e3cccafaafab162999e0
- git.kernel.org/stable/c/fbe3db4b650c284df8eb4cb68eebcf270cf861b5
- git.kernel.org/stable/c/fd20cc68bbdb5620696ac108e8f2efd180fe2c1a
Vendor advisories and official records. Exploit/PoC links are deliberately left out.