Bug 2383920 (CVE-2025-38478) - CVE-2025-38478 kernel: comedi: Fix initialization of data for instructions that write to subdevice
Summary: CVE-2025-38478 kernel: comedi: Fix initialization of data for instructions th...
Keywords:
Status: NEW
Alias: CVE-2025-38478
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: 2025-07-28 12:03 UTC by OSIDB Bzimport
Modified: 2025-07-28 13:11 UTC (History)
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Description OSIDB Bzimport 2025-07-28 12:03:19 UTC
In the Linux kernel, the following vulnerability has been resolved:

comedi: Fix initialization of data for instructions that write to subdevice

Some Comedi subdevice instruction handlers are known to access
instruction data elements beyond the first `insn->n` elements in some
cases.  The `do_insn_ioctl()` and `do_insnlist_ioctl()` functions
allocate at least `MIN_SAMPLES` (16) data elements to deal with this,
but they do not initialize all of that.  For Comedi instruction codes
that write to the subdevice, the first `insn->n` data elements are
copied from user-space, but the remaining elements are left
uninitialized.  That could be a problem if the subdevice instruction
handler reads the uninitialized data.  Ensure that the first
`MIN_SAMPLES` elements are initialized before calling these instruction
handlers, filling the uncopied elements with 0.  For
`do_insnlist_ioctl()`, the same data buffer elements are used for
handling a list of instructions, so ensure the first `MIN_SAMPLES`
elements are initialized for each instruction that writes to the
subdevice.

Comment 1 Avinash Hanwate 2025-07-28 13:08:43 UTC
Upstream advisory:
https://lore.kernel.org/linux-cve-announce/2025072814-CVE-2025-38478-298f@gregkh/T


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