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From: Junjie Cao <junjie.cao@intel.com>
To: qemu-devel@nongnu.org
Cc: junjie.cao@intel.com, mst@redhat.com, jasowang@redhat.com,
	yi.l.liu@intel.com, clement.mathieu--drif@bull.com,
	philmd@linaro.org, zhenzhong.duan@intel.com
Subject: [PATCH v2 0/2] intel_iommu: fix guest-triggerable assert in MMIO handlers
Date: Sat, 25 Apr 2026 04:18:40 +0800	[thread overview]
Message-ID: <20260424201842.176953-1-junjie.cao@intel.com> (raw)

An 8-byte guest access to any 32-bit-only VT-d register hits
assert(size == 4) and aborts QEMU.  Found by fuzzing with
generic-fuzz; 24 distinct crash inputs all share the same root cause.

v1: https://lore.kernel.org/all/20260420170523.17908-1-junjie.cao@intel.com/
v2: Per Philippe's suggestion, widen .impl.min_access_size to 8
instead of replacing asserts with guest-error checks.  This lets the
memory subsystem always pass size == 8 to the handler, eliminating
all 25 asserts and every size-based branch.

Junjie Cao (2):
  intel_iommu: widen impl.min_access_size to 8 to fix MMIO abort
  tests/qtest: add 8-byte MMIO access sweep for intel-iommu

 hw/i386/intel_iommu.c          | 121 +++++++--------------------------
 tests/qtest/intel-iommu-test.c |  30 ++++++++
 2 files changed, 53 insertions(+), 98 deletions(-)

-- 
2.43.0



             reply	other threads:[~2026-04-24 12:17 UTC|newest]

Thread overview: 15+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2026-04-24 20:18 Junjie Cao [this message]
2026-04-24 20:18 ` [PATCH v2 1/2] intel_iommu: widen impl.min_access_size to 8 to fix MMIO abort Junjie Cao
2026-04-24 13:58   ` Philippe Mathieu-Daudé
2026-04-27  1:24     ` Junjie Cao
2026-04-27  5:23   ` Duan, Zhenzhong
2026-04-30  0:16     ` Junjie Cao
2026-04-30  8:31       ` Duan, Zhenzhong
2026-05-06  3:19         ` [PATCH v3 0/2] intel_iommu: fix guest-triggerable assert in MMIO handlers Junjie Cao
2026-05-06  3:19         ` [PATCH v3 1/2] intel_iommu: fix guest-triggerable abort on oversized MMIO access Junjie Cao
2026-05-08  9:36           ` Yi Liu
2026-05-11  5:41             ` Duan, Zhenzhong
2026-05-14 13:42               ` Junjie Cao
2026-05-14  6:59                 ` Yi Liu
2026-05-06  3:19         ` [PATCH v3 2/2] tests/qtest: add 8-byte MMIO access sweep for intel-iommu Junjie Cao
2026-04-24 20:18 ` [PATCH v2 " Junjie Cao

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