Bug 2517069 (CVE-2026-74498) - CVE-2026-74498 kernel: ALSA: usb-audio: Fix DMA buffer out-of-bounds write when fill_max is set
Summary: CVE-2026-74498 kernel: ALSA: usb-audio: Fix DMA buffer out-of-bounds write wh...
Keywords:
Status: NEW
Alias: CVE-2026-74498
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: 2026-08-15 12:48 UTC by OSIDB Bzimport
Modified: 2026-08-19 15:54 UTC (History)
2 users (show)

Fixed In Version:
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Description OSIDB Bzimport 2026-08-15 12:48:03 UTC
In the Linux kernel, the following vulnerability has been resolved:

ALSA: usb-audio: Fix DMA buffer out-of-bounds write when fill_max is set

When a USB audio endpoint requests full packet transfers via the fill_max
descriptor flag, data_ep_set_params() promotes ep->curpacksize to
ep->maxpacksize. However, maxsize is left at the original sample-rate
derived value.

Since u->buffer_size is allocated as maxsize * packets, the resulting
DMA buffer is far too small for the requested transfer length. When the
USB host controller streams up to curpacksize bytes per packet, it writes
past the end of the buffer via DMA, corrupting kernel heap memory.

Update maxsize to curpacksize when fill_max is set so that the allocated
DMA buffer size matches the actual transfer request size.

[ changed to reassign maxsize only when ep->fill_max is set -- tiwai ]

Comment 1 Mauro Matteo Cascella 2026-08-19 15:37:04 UTC
Upstream advisory:
https://lore.kernel.org/linux-cve-announce/2026081540-CVE-2026-74498-ea47@gregkh/T


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