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PCI/P2PDMA: Fix 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.  If dev_pagemap.nr_range > 1, the memory following
the dev_pagemap could be overwritten.

This is currently not an issue because pci_p2pdma_pagemap is not exposed
outside p2pdma.c, and p2pdma.c only sets dev_pagemap.nr_range to 1.

To prevent problems if p2pdma.c ever uses nr_range > 1, move the flexible
struct dev_pagemap to 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.

Link: https://lore.kernel.org/r/ZRsUL/hATNruwtla@work
Signed-off-by: "Gustavo A. R. Silva" <gustavoars@kernel.org>
[bhelgaas: commit log]
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Reviewed-by: Logan Gunthorpe <logang@deltatee.com>
This commit is contained in:
Gustavo A. R. Silva 2023-10-02 21:04:15 +02:00 committed by Bjorn Helgaas
parent 0bb80ecc33
commit 4a7ce83349
1 changed files with 1 additions and 1 deletions
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2
drivers/pci/p2pdma.c
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@ -28,9 +28,9 @@ struct pci_p2pdma {
}; };
struct pci_p2pdma_pagemap { struct pci_p2pdma_pagemap {
struct dev_pagemap pgmap;
struct pci_dev *provider; struct pci_dev *provider;
u64 bus_offset; u64 bus_offset;
struct dev_pagemap pgmap;
}; };
static struct pci_p2pdma_pagemap *to_p2p_pgmap(struct dev_pagemap *pgmap) static struct pci_p2pdma_pagemap *to_p2p_pgmap(struct dev_pagemap *pgmap)