From: Mostafa Saleh smostafa@google.com

commit 9eee5330656bf92f51cb1f09b2dc9f8cf975b3d1 upstream.

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 tglx@linutronix.de Signed-off-by: Mostafa Saleh smostafa@google.com Signed-off-by: Thomas Gleixner tglx@linutronix.de Cc: Bjorn Heelgas bhelgaas@google.com Cc: stable@vger.kernel.org Link: https://lore.kernel.org/r/20240624203729.1094506-1-smostafa@google.com Signed-off-by: Hugo SIMELIERE hsimeliere.opensource@witekio.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 fdd2ec09651e..c5cc3e453fd0 100644 --- a/drivers/pci/msi/msi.c +++ b/drivers/pci/msi/msi.c @@ -431,7 +431,7 @@ 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;

/* @@ -452,6 +452,12 @@ 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); @@ -471,7 +477,7 @@ 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)); free_msi_irqs(dev); fail: dev->msi_enabled = 0;