Bug 2525427 (CVE-2026-80710) - CVE-2026-80710 kernel: s390/dasd: Fix undersized format-check buffer
Summary: CVE-2026-80710 kernel: s390/dasd: Fix undersized format-check buffer
Keywords:
Status: NEW
Alias: CVE-2026-80710
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: 2026-08-28 07:44 UTC by OSIDB Bzimport
Modified: 2026-09-03 15:46 UTC (History)
2 users (show)

Fixed In Version:
Clone Of:
Environment:
Last Closed:
Embargoed:


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Description OSIDB Bzimport 2026-08-28 07:44:26 UTC
In the Linux kernel, the following vulnerability has been resolved:

s390/dasd: Fix undersized format-check buffer

fmt_buffer_size in dasd_eckd_check_device_format() is declared as
int, even though one of the multiplicands, sizeof(struct eckd_count),
is a size_t. The expression

    trkcount * rpt_max * sizeof(struct eckd_count)

is therefore correctly evaluated at 64-bit width, but the result is
silently truncated when it is stored back into the 32-bit
fmt_buffer_size variable. For a sufficiently large track range
(start_unit/stop_unit are caller-controlled) this truncation
yields a buffer size far smaller than the number of tracks actually
requested. kzalloc() then succeeds with an undersized allocation,
while the subsequent channel program build still operates on the
untruncated track count and writes past the end of that buffer.

Compute the buffer size with check_mul_overflow() and keep it in a
size_t, so that a value that no longer fits results in -EINVAL
instead of a silently truncated allocation size.


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