Messages in this thread Patch in this message | | | Date | Mon, 2 Oct 2023 21:04:15 +0200 | From | "Gustavo A. R. Silva" <> | Subject | [PATCH v2][next] PCI/P2PDMA: Fix potential undefined behavior bug in struct pci_p2pdma_pagemap |
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`struct dev_pagemap` is a flexible structure, which means that it contains a flexible-array member at the bottom. This could potentially lead to an overwrite of the objects following `pgmap` in `struct pci_p2pdma_pagemap`, when `nr_range > 1`. This is currently not the case (notice that `nr_range` is hardcoded to `1`), however as commit b7b3c01b1915 ("mm/memremap_pages: support multiple ranges per invocation") mentions in the subject line, this code can `support multiple ranges per invocation`. So, we'd better prevent any problems that may arise in the future.
Fix this by placing the declaration of object `pgmap` at the end of `struct pci_p2pdma_pagemap`.
-Wflex-array-member-not-at-end is coming in GCC-14, and we are getting ready to enable it globally.
Reviewed-by: Logan Gunthorpe <logang@deltatee.com> Signed-off-by: Gustavo A. R. Silva <gustavoars@kernel.org> --- Changes in v2: - Remove `Fixes:` tags. (Logan Gunthorpe) - Update changelog text. Make it clear that `nr_range` is hardcoded to `1` (Logan Gunthorpe) - Update subject. - Add Logan's RB.
v1: Link: https://lore.kernel.org/linux-hardening/ZRnf6wVOu0IJQ2Ok@work/
drivers/pci/p2pdma.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/drivers/pci/p2pdma.c b/drivers/pci/p2pdma.c index fa7370f9561a..ab34d3d36a64 100644 --- a/drivers/pci/p2pdma.c +++ b/drivers/pci/p2pdma.c @@ -28,9 +28,9 @@ struct pci_p2pdma { }; struct pci_p2pdma_pagemap { - struct dev_pagemap pgmap; struct pci_dev *provider; u64 bus_offset; + struct dev_pagemap pgmap; }; static struct pci_p2pdma_pagemap *to_p2p_pgmap(struct dev_pagemap *pgmap) -- 2.34.1
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