`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@xxxxxxxxxxxx>
Signed-off-by: Gustavo A. R. Silva <gustavoars@xxxxxxxxxx>
---
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
