From 9eee5330656bf92f51cb1f09b2dc9f8cf975b3d1 Mon Sep 17 00:00:00 2001 From: Mostafa Saleh Date: Mon, 24 Jun 2024 20:37:28 +0000 Subject: [PATCH] PCI/MSI: Fix UAF in msi_capability_init KFENCE reports the following UAF: BUG: KFENCE: use-after-free read in __pci_enable_msi_range+0x2c0/0x488 Use-after-free read at 0x0000000024629571 (in kfence-#12): __pci_enable_msi_range+0x2c0/0x488 pci_alloc_irq_vectors_affinity+0xec/0x14c pci_alloc_irq_vectors+0x18/0x28 kfence-#12: 0x0000000008614900-0x00000000e06c228d, size=104, cache=kmalloc-128 allocated by task 81 on cpu 7 at 10.808142s: __kmem_cache_alloc_node+0x1f0/0x2bc kmalloc_trace+0x44/0x138 msi_alloc_desc+0x3c/0x9c msi_domain_insert_msi_desc+0x30/0x78 msi_setup_msi_desc+0x13c/0x184 __pci_enable_msi_range+0x258/0x488 pci_alloc_irq_vectors_affinity+0xec/0x14c pci_alloc_irq_vectors+0x18/0x28 freed by task 81 on cpu 7 at 10.811436s: msi_domain_free_descs+0xd4/0x10c msi_domain_free_locked.part.0+0xc0/0x1d8 msi_domain_alloc_irqs_all_locked+0xb4/0xbc pci_msi_setup_msi_irqs+0x30/0x4c __pci_enable_msi_range+0x2a8/0x488 pci_alloc_irq_vectors_affinity+0xec/0x14c pci_alloc_irq_vectors+0x18/0x28 Descriptor allocation done in: __pci_enable_msi_range msi_capability_init msi_setup_msi_desc msi_insert_msi_desc msi_domain_insert_msi_desc msi_alloc_desc ... Freed in case of failure in __msi_domain_alloc_locked() __pci_enable_msi_range msi_capability_init pci_msi_setup_msi_irqs msi_domain_alloc_irqs_all_locked msi_domain_alloc_locked __msi_domain_alloc_locked => fails msi_domain_free_locked ... That failure propagates back to pci_msi_setup_msi_irqs() in msi_capability_init() which accesses the descriptor for unmasking in the error exit path. Cure it by copying the descriptor and using the copy for the error exit path unmask operation. [ tglx: Massaged change log ] Fixes: bf6e054e0e3f ("genirq/msi: Provide msi_device_populate/destroy_sysfs()") Suggested-by: Thomas Gleixner Signed-off-by: Mostafa Saleh Signed-off-by: Thomas Gleixner Cc: Bjorn Heelgas Cc: stable@vger.kernel.org Link: https://lore.kernel.org/r/20240624203729.1094506-1-smostafa@google.com --- drivers/pci/msi/msi.c | 10 ++++++++-- 1 file changed, 8 insertions(+), 2 deletions(-) diff --git a/drivers/pci/msi/msi.c b/drivers/pci/msi/msi.c index c5625dd9bf490d..3a45879d85db96 100644 --- a/drivers/pci/msi/msi.c +++ b/drivers/pci/msi/msi.c @@ -352,7 +352,7 @@ static int msi_capability_init(struct pci_dev *dev, int nvec, struct irq_affinity *affd) { struct irq_affinity_desc *masks = NULL; - struct msi_desc *entry; + struct msi_desc *entry, desc; int ret; /* Reject multi-MSI early on irq domain enabled architectures */ @@ -377,6 +377,12 @@ static int msi_capability_init(struct pci_dev *dev, int nvec, /* All MSIs are unmasked by default; mask them all */ entry = msi_first_desc(&dev->dev, MSI_DESC_ALL); pci_msi_mask(entry, msi_multi_mask(entry)); + /* + * Copy the MSI descriptor for the error path because + * pci_msi_setup_msi_irqs() will free it for the hierarchical + * interrupt domain case. + */ + memcpy(&desc, entry, sizeof(desc)); /* Configure MSI capability structure */ ret = pci_msi_setup_msi_irqs(dev, nvec, PCI_CAP_ID_MSI); @@ -396,7 +402,7 @@ static int msi_capability_init(struct pci_dev *dev, int nvec, goto unlock; err: - pci_msi_unmask(entry, msi_multi_mask(entry)); + pci_msi_unmask(&desc, msi_multi_mask(&desc)); pci_free_msi_irqs(dev); fail: dev->msi_enabled = 0;