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Fri, 28 Aug 2026 05:54:17 -0700 (PDT) Date: Fri, 28 Aug 2026 12:53:37 +0000 In-Reply-To: <20260828125409.1921538-1-smostafa@google.com> Mime-Version: 1.0 References: <20260828125409.1921538-1-smostafa@google.com> X-Mailer: git-send-email 2.55.0.897.gb25b4bd76c-goog Message-ID: <20260828125409.1921538-3-smostafa@google.com> Subject: [PATCH 2/7] iommu/arm-smmu-v3: Prevent rbtree corruption from duplicate streams From: Mostafa Saleh To: linux-kernel@vger.kernel.org, iommu@lists.linux.dev, linux-arm-kernel@lists.infradead.org Cc: will@kernel.org, robin.murphy@arm.com, joro@8bytes.org, jgg@ziepe.ca, nicolinc@nvidia.com, praan@google.com, Mostafa Saleh Content-Type: text/plain; charset="UTF-8" X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.9.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20260828_055421_345317_517752D6 X-CRM114-Status: GOOD ( 14.34 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org In handling PCI devices with duplicate IDs, arm_smmu_insert_master() will continue the loop skipping the duplicate sids insertion in the rbtree. However, in the error path of arm_smmu_insert_master() and in arm_smmu_remove_master(), the code loops over all fwspec->num_ids and calls rb_erase() unconditionally. For the duplicate streams, the node is zero allocated including the parent pointer "__rb_parent_color". That means rb_erase() will think that this node is root and it will corrupt the tree which includes other masters not being removed. Fix this by initializing those nodes with RB_CLEAR_NODE() and check if they are empty before erasing. Fixes: cdf315f907d4 ("iommu/arm-smmu-v3: Maintain a SID->device structure") Reported-by: Sashiko <> Signed-off-by: Mostafa Saleh --- drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c | 16 +++++++++++----- 1 file changed, 11 insertions(+), 5 deletions(-) diff --git a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c index 494bbfd2869f..36e3778c971e 100644 --- a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c +++ b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c @@ -4147,8 +4147,10 @@ static int arm_smmu_insert_master(struct arm_smmu_device *smmu, ->master; /* Bridged PCI devices may end up with duplicated IDs */ - if (existing_master == master) + if (existing_master == master) { + RB_CLEAR_NODE(&new_stream->node); continue; + } dev_warn(master->dev, "Aliasing StreamID 0x%x (from %s) unsupported, expect DMA to be broken\n", @@ -4159,8 +4161,10 @@ static int arm_smmu_insert_master(struct arm_smmu_device *smmu, } if (ret) { - for (i--; i >= 0; i--) - rb_erase(&master->streams[i].node, &smmu->streams); + for (i--; i >= 0; i--) { + if (!RB_EMPTY_NODE(&master->streams[i].node)) + rb_erase(&master->streams[i].node, &smmu->streams); + } kfree(master->streams); kfree(master->build_invs); } @@ -4179,8 +4183,10 @@ static void arm_smmu_remove_master(struct arm_smmu_master *master) return; mutex_lock(&smmu->streams_mutex); - for (i = 0; i < fwspec->num_ids; i++) - rb_erase(&master->streams[i].node, &smmu->streams); + for (i = 0; i < fwspec->num_ids; i++) { + if (!RB_EMPTY_NODE(&master->streams[i].node)) + rb_erase(&master->streams[i].node, &smmu->streams); + } mutex_unlock(&smmu->streams_mutex); kfree(master->streams); -- 2.55.0.897.gb25b4bd76c-goog