Bug 2535112 (CVE-2026-89891) - CVE-2026-89891 kernel: media: em28xx: fix use-after-free of dev_next->devlist on disconnect
Summary: CVE-2026-89891 kernel: media: em28xx: fix use-after-free of dev_next->devlist...
Keywords:
Status: NEW
Alias: CVE-2026-89891
Product: Security Response
Classification: Other
Component: vulnerability
Version: unspecified
Hardware: All
OS: Linux
medium
medium
Target Milestone: ---
Assignee: Product Security DevOps Team
QA Contact:
URL:
Whiteboard:
Depends On:
Blocks:
TreeView+ depends on / blocked
 
Reported: 2026-09-16 10:47 UTC by OSIDB Bzimport
Modified: 2026-10-23 22:39 UTC (History)
17 users (show)

Fixed In Version:
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Description OSIDB Bzimport 2026-09-16 10:47:21 UTC
In the Linux kernel, the following vulnerability has been resolved:

media: em28xx: fix use-after-free of dev_next->devlist on disconnect

When a device with has_dual_ts=1 is probed and the is_audio_only path
is taken, both dev and dev->dev_next are added to the global
em28xx_devlist via em28xx_init_extension(). However, during disconnect,
em28xx_close_extension(dev) only calls list_del(&dev->devlist), leaving
dev->dev_next->devlist still linked in the global list. When dev_next is
subsequently freed via kref_put(), its devlist entry becomes a dangling
pointer in em28xx_devlist. The next device probe that calls
em28xx_init_extension() triggers a list corruption BUG when list_add_tail
detects the freed node.

This bug was exposed by commit a368ecde8a50 ("USB: core: Fix duplicate
endpoint bug by clearing reserved bits in the descriptor") which clears
reserved bits in bEndpointAddress during endpoint parsing. This causes
fuzzed endpoint addresses like 0xf3 to be normalized to 0x83, which
em28xx interprets as a vendor audio endpoint, enabling the
is_audio_only + has_dual_ts code path that was previously unreachable
with such descriptors.

Fix this by removing dev->dev_next->devlist from the global list in
em28xx_close_extension() before the device is freed.


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