[PATCH 4.10 02/62] sparc64: kern_addr_valid regression

From: Greg Kroah-Hartman
Date: Mon May 01 2017 - 17:43:45 EST

4.10-stable review patch. If anyone has any objections, please let me know.


From: bob picco <bob.picco@xxxxxxxxxx>

[ Upstream commit adfae8a5d833fa2b46577a8081f350e408851f5b ]

I encountered this bug when using /proc/kcore to examine the kernel. Plus a
coworker inquired about debugging tools. We computed pa but did
not use it during the maximum physical address bits test. Instead we used
the identity mapped virtual address which will always fail this test.

I believe the defect came in here:
[bpicco@zareason linus.git]$ git describe --contains bb4e6e85daa52

Signed-off-by: Bob Picco <bob.picco@xxxxxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
arch/sparc/mm/init_64.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

--- a/arch/sparc/mm/init_64.c
+++ b/arch/sparc/mm/init_64.c
@@ -1495,7 +1495,7 @@ bool kern_addr_valid(unsigned long addr)
if ((long)addr < 0L) {
unsigned long pa = __pa(addr);

- if ((addr >> max_phys_bits) != 0UL)
+ if ((pa >> max_phys_bits) != 0UL)
return false;

return pfn_valid(pa >> PAGE_SHIFT);