[PATCH 3.16 261/366] MIPS: Fix off-by-one in pci_resource_to_user()

Ben Hutchings
2018-11-11T20:02:51Z

From: Paul Burton <paul.burton@mips.com>

commit 38c0a74fe06da3be133cae3fb7bde6a9438e698b upstream.

The MIPS implementation of pci_resource_to_user() introduced in v3.12 by
commit 4c2924b725fb ("MIPS: PCI: Use pci_resource_to_user to map pci
memory space properly") incorrectly sets *end to the address of the
byte after the resource, rather than the last byte of the resource.

This results in userland seeing resources as a byte larger than they
actually are, for example a 32 byte BAR will be reported by a tool such
as lspci as being 33 bytes in size:

Region 2: I/O ports at 1000 [disabled] [size=33]

Correct this by subtracting one from the calculated end address,
reporting the correct address to userland.

Signed-off-by: Paul Burton <paul.burton@mips.com>
Reported-by: Rui Wang <rui.wang@windriver.com>
Fixes: 4c2924b725fb ("MIPS: PCI: Use pci_resource_to_user to map pci memory space properly")
Cc: James Hogan <jhogan@kernel.org>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: Wolfgang Grandegger <wg@grandegger.com>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/19829/
[bwh: Backported to 3.16: adjust filename]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
---
arch/mips/include/asm/pci.h | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

--- a/arch/mips/include/asm/pci.h
+++ b/arch/mips/include/asm/pci.h
@@ -87,7 +87,7 @@ static inline void pci_resource_to_user(
phys_t size = resource_size(rsrc);

*start = fixup_bigphys_addr(rsrc->start, size);
- *end = rsrc->start + size;
+ *end = rsrc->start + size - 1;
}

/*