3.14-stable review patch. If anyone has any objections, please let me know.
------------------
From: "David S. Miller" <davem@xxxxxxxxxxxxx>
[ Upstream commit e5c460f46ae7ee94831cb55cb980f942aa9e5a85 ]
This was found using Dave Jone's trinity tool.
When a user process which is 32-bit performs a load or a store, the
cpu chops off the top 32-bits of the effective address before
translating it.
This is because we run 32-bit tasks with the PSTATE_AM (address
masking) bit set.
We can't run the kernel with that bit set, so when the kernel accesses
userspace no address masking occurs.
Since a 32-bit process will have no mappings in that region we will
properly fault, so we don't try to handle this using access_ok(),
which can safely just be a NOP on sparc64.
Real faults from 32-bit processes should never generate such addresses
so a bug check was added long ago, and it barks in the logs if this
happens.
But it also barks when a kernel user access causes this condition, and
that _can_ happen. For example, if a pointer passed into a system call
is "0xfffffffc" and the kernel access 4 bytes offset from that pointer.
Just handle such faults normally via the exception entries.
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
arch/sparc/mm/fault_64.c | 16 +---------------
1 file changed, 1 insertion(+), 15 deletions(-)
--- a/arch/sparc/mm/fault_64.c
+++ b/arch/sparc/mm/fault_64.c
@@ -281,18 +281,6 @@ static void noinline __kprobes bogus_32b
show_regs(regs);
}
-static void noinline __kprobes bogus_32bit_fault_address(struct pt_regs *regs,
- unsigned long addr)
-{
- static int times;
-
- if (times++ < 10)
- printk(KERN_ERR "FAULT[%s:%d]: 32-bit process "
- "reports 64-bit fault address [%lx]\n",
- current->comm, current->pid, addr);
- show_regs(regs);
-}
-
asmlinkage void __kprobes do_sparc64_fault(struct pt_regs *regs)
{
enum ctx_state prev_state = exception_enter();
@@ -322,10 +310,8 @@ asmlinkage void __kprobes do_sparc64_fau
goto intr_or_no_mm;
}
}
- if (unlikely((address >> 32) != 0)) {
- bogus_32bit_fault_address(regs, address);
+ if (unlikely((address >> 32) != 0))
goto intr_or_no_mm;
- }
}
if (regs->tstate & TSTATE_PRIV) {
--
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