From 2888520bdcbe0599cfc77b2fad8dc6c95505a3cb Mon Sep 17 00:00:00 2001 From: Nicolin Chen Date: Wed, 23 Sep 2026 13:11:25 -0700 Subject: [PATCH] iommu/arm-smmu-v3: Don't rb_erase() a never-inserted stream node arm_smmu_insert_master() skips inserting a stream whose StreamID duplicates one the same master already owns (bridged PCI devices can present duplicate IDs), leaving that master->streams[i].node zeroed and unlinked from the smmu->streams rb-tree. Both the insert error-rollback loop and arm_smmu_remove_master() then call rb_erase() on every master->streams[i].node unconditionally. rb_erase() on a zeroed node sees a NULL parent, treats the node as the tree root and sets root->rb_node = NULL, silently emptying the whole SID tree and breaking SID lookups (and DMA) for every other master on the SMMU. Mark each node with RB_CLEAR_NODE() after sort_nonatomic() reorders the array, since sorting relocates the entries and would leave the earlier self-referential RB_CLEAR_NODE() pointer stale. An un-inserted node then stays RB_EMPTY_NODE() and is skipped in both erase loops; inserted nodes are linked by rb_find_add() and erased as before. Fixes: b00d24997a11 ("iommu/arm-smmu-v3: Fix iommu_device_probe bug due to duplicated stream ids") Assisted-by: LLM Signed-off-by: Nicolin Chen Reviewed-by: Mostafa Saleh Signed-off-by: Will Deacon --- drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c | 14 ++++++++++++-- 1 file changed, 12 insertions(+), 2 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 7d2415143407..34e916ea339f 100644 --- a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c +++ b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c @@ -4320,6 +4320,13 @@ static int arm_smmu_insert_master(struct arm_smmu_device *smmu, sizeof(master->streams[0]), arm_smmu_stream_id_cmp, NULL); + /* + * Clear after sorting: RB_CLEAR_NODE() records the node's own address, + * which sort_nonatomic() invalidates by relocating the entries. + */ + for (i = 0; i < fwspec->num_ids; i++) + RB_CLEAR_NODE(&master->streams[i].node); + mutex_lock(&smmu->streams_mutex); for (i = 0; i < fwspec->num_ids; i++) { struct arm_smmu_stream *new_stream = &master->streams[i]; @@ -4352,7 +4359,9 @@ 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); + if (!RB_EMPTY_NODE(&master->streams[i].node)) + rb_erase(&master->streams[i].node, + &smmu->streams); kfree(master->streams); kfree(master->build_invs); } @@ -4372,7 +4381,8 @@ static void arm_smmu_remove_master(struct arm_smmu_master *master) mutex_lock(&smmu->streams_mutex); for (i = 0; i < fwspec->num_ids; i++) - rb_erase(&master->streams[i].node, &smmu->streams); + if (!RB_EMPTY_NODE(&master->streams[i].node)) + rb_erase(&master->streams[i].node, &smmu->streams); mutex_unlock(&smmu->streams_mutex); kfree(master->streams);