From: Ilpo Järvinen Date: Mon, 24 Nov 2025 15:37:40 +0000 (+0200) Subject: PCI: Validate pci_rebar_size_supported() input X-Git-Url: https://gentwo.org/gitweb/?a=commitdiff_plain;h=48f014356698a3525959a9eb343dc67b5a5c6842;p=linux%2F.git PCI: Validate pci_rebar_size_supported() input According to Dan Carpenter, smatch detects issue with size parameter given to pci_rebar_size_supported(): drivers/pci/rebar.c:142 pci_rebar_size_supported() error: undefined (user controlled) shift '(((1))) << size' The problem is this call tree, which uses the 'size' from the user to shift in BIT() without validating it: __resource_resize_store # takes 'buf' from user sysfs write kstrtoul(buf, 0, &size) # converts to unsigned long pci_resize_resource # truncates to int pci_rebar_size_supported # BIT(size) without validation There could be similar problems also with pci_resize_resource() parameter values coming from drivers. Add 'size' validation to pci_rebar_size_supported(). There seems to be no SZ_128T prior to this so add one to be able to specify the largest size supported by the kernel (PCIe r7.0 spec already defines sizes even beyond 128TB but kernel does not yet support them). The issue looks older than the introduction of pci_rebar_size_supported() by bb1fabd0d94e ("PCI: Add pci_rebar_size_supported() helper"). It would be also nice to convert 'size' unsigned too everywhere, maybe even u8 but that is left as further work. Fixes: 8bb705e3e79d ("PCI: Add pci_resize_resource() for resizing BARs") Reported-by: Dan Carpenter Closes: https://lore.kernel.org/r/aSA1WiRG3RuhqZMY@stanley.mountain/ Signed-off-by: Ilpo Järvinen [bhelgaas: commit log, add report URL] Signed-off-by: Bjorn Helgaas Link: https://patch.msgid.link/20251124153740.2995-1-ilpo.jarvinen@linux.intel.com --- diff --git a/drivers/pci/rebar.c b/drivers/pci/rebar.c index 7f6dece19138..ecdebdeb2dff 100644 --- a/drivers/pci/rebar.c +++ b/drivers/pci/rebar.c @@ -139,6 +139,9 @@ bool pci_rebar_size_supported(struct pci_dev *pdev, int bar, int size) { u64 sizes = pci_rebar_get_possible_sizes(pdev, bar); + if (size < 0 || size > ilog2(SZ_128T) - ilog2(PCI_REBAR_MIN_SIZE)) + return false; + return BIT(size) & sizes; } EXPORT_SYMBOL_GPL(pci_rebar_size_supported); diff --git a/include/linux/sizes.h b/include/linux/sizes.h index 49039494076f..f1f1a055b047 100644 --- a/include/linux/sizes.h +++ b/include/linux/sizes.h @@ -67,5 +67,6 @@ #define SZ_16T _AC(0x100000000000, ULL) #define SZ_32T _AC(0x200000000000, ULL) #define SZ_64T _AC(0x400000000000, ULL) +#define SZ_128T _AC(0x800000000000, ULL) #endif /* __LINUX_SIZES_H__ */