Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:
Pre-existing issues: - [High] Skipping `synchronize_rcu()` when `p2pdma->pool` is NULL causes a Use-After-Free of `pdev->p2pdma` and its XArray. -- --- Patch [2]: [PATCH v5 2/9] PCI/P2PDMA: Add CONFIG_PCI_P2PDMA_CORE --- commit 963552636d1deb6dc48ba93e918ef61646e05d1a Author: Matt Evans <[email protected]> PCI/P2PDMA: Add CONFIG_PCI_P2PDMA_CORE This commit introduces CONFIG_PCI_P2PDMA_CORE and refactors the basic provider functionality into a new p2pdma_core.c file. This allows drivers to use pcim_p2pdma_provider() without a hard dependency on the full P2P DMA management features. > diff --git a/drivers/pci/p2pdma_core.c b/drivers/pci/p2pdma_core.c > new file mode 100644 > --- /dev/null > +++ b/drivers/pci/p2pdma_core.c [ ... ] > +static void pci_p2pdma_release(void *data) > +{ > + struct pci_dev *pdev = data; > + struct pci_p2pdma *p2pdma; > + > + p2pdma = rcu_dereference_protected(pdev->p2pdma, 1); > + if (!p2pdma) > + return; > + > + /* Flush and disable pci_alloc_p2p_mem() */ > + pdev->p2pdma = NULL; > + pci_p2pdma_release_pool(pdev, p2pdma); > + xa_destroy(&p2pdma->map_types); > +} [Severity: High] This is a pre-existing issue, but does skipping synchronize_rcu() when the pool is NULL lead to a use-after-free? Looking at pci_p2pdma_release_pool() in drivers/pci/p2pdma.c, it skips synchronize_rcu() if the pool has not been set up: void pci_p2pdma_release_pool(struct pci_dev *pdev, struct pci_p2pdma *p2pdma) { if (!p2pdma->pool) return; synchronize_rcu(); gen_pool_destroy(p2pdma->pool); sysfs_remove_group(&pdev->dev.kobj, &p2pmem_group); } If a driver initializes P2PDMA without setting up a pool, p2pdma->pool will be NULL. When the device is unbound, devres executes pci_p2pdma_release(). Because pci_p2pdma_release_pool() returns early, synchronize_rcu() is skipped. pci_p2pdma_release() then immediately calls xa_destroy(&p2pdma->map_types) and the p2pdma structure is freed. Could concurrent RCU readers, such as pci_p2pdma_map_type() during a DMA-BUF mapping, access the destroyed xarray or the freed struct and trigger a use-after-free? -- Sashiko AI review ยท https://sashiko.dev/#/patchset/[email protected]?part=2
