3.16.48-rc1 review patch. If anyone has any objections, please let me know.
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From: Julius Werner <jwerner@xxxxxxxxxxxx>
commit 32829da54d9368103a2f03269a5120aa9ee4d5da upstream.
A recent fix to /dev/mem prevents mappings from wrapping around the end
of physical address space. However, the check was written in a way that
also prevents a mapping reaching just up to the end of physical address
space, which may be a valid use case (especially on 32-bit systems).
This patch fixes it by checking the last mapped address (instead of the
first address behind that) for overflow.
Fixes: b299cde245 ("drivers: char: mem: Check for address space wraparound with mmap()")
Reported-by: Nico Huber <nico.h@xxxxxx>
Signed-off-by: Julius Werner <jwerner@xxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
Signed-off-by: Ben Hutchings <ben@xxxxxxxxxxxxxxx>
---
drivers/char/mem.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
--- a/drivers/char/mem.c
+++ b/drivers/char/mem.c
@@ -332,7 +332,7 @@ static int mmap_mem(struct file *file, s
phys_addr_t offset = (phys_addr_t)vma->vm_pgoff << PAGE_SHIFT;
/* It's illegal to wrap around the end of the physical address space. */
- if (offset + (phys_addr_t)size < offset)
+ if (offset + (phys_addr_t)size - 1 < offset)
return -EINVAL;
if (!valid_mmap_phys_addr_range(vma->vm_pgoff, size))