drm/xe: harden adjust_idledly() against divide-by-zero and overflow
Summary
| CVE | CVE-2026-98919 |
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| State | PUBLISHED |
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| Assigner | Linux |
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| Source Priority | CVE Program / NVD first with legacy fallback |
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| Published | 2026-10-23 13:17:12 UTC |
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| Updated | 2026-10-23 13:17:12 UTC |
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| Description | In the Linux kernel, the following vulnerability has been resolved:
drm/xe: harden adjust_idledly() against divide-by-zero and overflow
adjust_idledly() has several corner-case issues flagged during review:
1. If xe_gt_clock_init() failed to recognise the crystal clock,
gt->info.timestamp_base is 0, which makes idledly_units_ps also 0.
The subsequent DIV_ROUND_CLOSEST(..., idledly_units_ps) is then a
divide-by-zero and panics the kernel.
2. The tick-to-ns conversions are done in u32:
idledly * idledly_units_ps, (maxcnt - 1) * 1000
Both overflow u32 before DIV_ROUND_CLOSEST() sees them.
3. If IDLE_WAIT_TIME reads back as 0, maxcnt evaluates to 0 and
the maxcnt - 1 clamp wraps to 0xFFFFFFFF in u32.
4. The register only stores whole ticks, so the clamped ns value has
to be converted to ticks and back. DIV_ROUND_CLOSEST() can round
that conversion up past maxcnt:
maxcnt = 640 ns, one tick = 666664 ps
clamp: maxcnt - 1 = 639 ns
ns -> ticks: 639000 / 666664 = 0.958 -> rounds to 1 tick
tick -> ns: 1 * 666664 / 1000 = 667 ns
667 ns is programmed into RING_IDLEDLY, but 667 >= maxcnt (640),
so xe_gt_WARN_ON() fires again on every subsequent init.
Return early if timestamp_base is 0 (the unknown-crystal path).
Do the conversions in u64 via the *_ULL() helpers so they cannot wrap.
Clamp with a floor (DIV_ROUND_DOWN_ULL) so the programmed delay stays
strictly below maxcnt, and guard the maxcnt == 0 case with a zero delay
while still writing RING_IDLEDLY so INHIBIT_SWITCH_UNTIL_PREEMPTED is
cleared.
v2: Drop the redundant warn on the timestamp_base == 0 path;
xe_gt_clock_init() already warns on an unrecognised crystal clock.
Keep the early return to avoid the divide-by-zero. - Vinay
v3: Field-mask the RING_IDLEDLY write with REG_FIELD_PREP(IDLE_DELAY, ...)
instead of writing the raw tick count, which could clobber
INHIBIT_SWITCH_UNTIL_PREEMPTED and reserved bits. Split the
inhibit-switch clear from the maxcnt clamp so a set inhibit bit no
longer forces a needless delay overwrite when the delay itself is
already valid. Use gt_to_xe(gt) instead of gt_to_xe(hwe->gt).
(cherry picked from commit d864065ea25e9d12897c175de9176ce46677e176) |
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Vendor Declared Affected Products
| Source | Vendor | Product | Version | Platforms |
|---|
| CNA |
Linux |
Linux |
affected d2de4410a88ffc6053300d03041cc73b8c85dbaf 2bcbfc5e7bfa9cc76818c54db698da5bdc13d9ff git |
Not specified |
| CNA |
Linux |
Linux |
affected d2de4410a88ffc6053300d03041cc73b8c85dbaf 531d4cd03118224022dc21ae25af052ce2a9e267 git |
Not specified |
| CNA |
Linux |
Linux |
affected d2de4410a88ffc6053300d03041cc73b8c85dbaf 90f467577ebc28c5bc4ba2f0f1b83a4419fb0740 git |
Not specified |
| CNA |
Linux |
Linux |
affected 6.15 |
Not specified |
| CNA |
Linux |
Linux |
unaffected 6.15 semver |
Not specified |
| CNA |
Linux |
Linux |
unaffected 6.18.55 6.18.* semver |
Not specified |
| CNA |
Linux |
Linux |
unaffected 7.2.9 7.2.* semver |
Not specified |
| CNA |
Linux |
Linux |
unaffected 7.3 * original_commit_for_fix |
Not specified |
References
| Reference | Source | Link | Tags |
|---|
| git.kernel.org/stable/c/531d4cd03118224022dc21ae25af052ce2a9e267 |
416baaa9-dc9f-4396-8d5f-8c081fb06d67 |
git.kernel.org |
|
| git.kernel.org/stable/c/90f467577ebc28c5bc4ba2f0f1b83a4419fb0740 |
416baaa9-dc9f-4396-8d5f-8c081fb06d67 |
git.kernel.org |
|
| git.kernel.org/stable/c/2bcbfc5e7bfa9cc76818c54db698da5bdc13d9ff |
416baaa9-dc9f-4396-8d5f-8c081fb06d67 |
git.kernel.org |
|
| CVE Program record |
CVE.ORG |
www.cve.org |
canonical |
| NVD vulnerability detail |
NVD |
nvd.nist.gov |
canonical, analysis |
No vendor comments have been submitted for this CVE.
There are currently no legacy QID mappings associated with this CVE.