From: Anton Blanchard <an...@samba.org>
__kernel_get_syscall_map and __kernel_clock_getres use cmpli to
check if the passed in pointer is non zero. cmpli maps to a 32 bit
compare on binutils, so we ignore the top 32 bits.
A simple test case can be created by passing in a bogus pointer with
the bottom 32 bits clear. Using a clk_id that is handled by the VDSO,
then one that is handled by the kernel shows the problem:
printf("%d\n", clock_getres(CLOCK_REALTIME, (void *)0x100000000));
printf("%d\n", clock_getres(CLOCK_BOOTTIME, (void *)0x100000000));
And we get:
0
-1
The bigger issue is if we pass a valid pointer with the bottom 32 bits
clear, in this case we will return success but won't write any data
to the pointer.
I stumbled across this issue because the LLVM integrated assembler
doesn't accept cmpli with 3 arguments. Fix this by converting them to
cmpldi.
Cc: sta...@vger.kernel.org
Signed-off-by: Anton Blanchard <an...@samba.org>
---
arch/powerpc/kernel/vdso64/datapage.S | 2 +-
arch/powerpc/kernel/vdso64/gettimeofday.S | 2 +-
2 files changed, 2 insertions(+), 2 deletions(-)
diff --git a/arch/powerpc/kernel/vdso64/datapage.S
b/arch/powerpc/kernel/vdso64/datapage.S
index 184a6ba..abf17fe 100644
--- a/arch/powerpc/kernel/vdso64/datapage.S
+++ b/arch/powerpc/kernel/vdso64/datapage.S
@@ -59,7 +59,7 @@ V_FUNCTION_BEGIN(__kernel_get_syscall_map)
bl V_LOCAL_FUNC(__get_datapage)
mtlr r12
addi r3,r3,CFG_SYSCALL_MAP64
- cmpli cr0,r4,0
+ cmpldi cr0,r4,0
crclr cr0*4+so
beqlr
li r0,NR_syscalls
diff --git a/arch/powerpc/kernel/vdso64/gettimeofday.S
b/arch/powerpc/kernel/vdso64/gettimeofday.S
index a76b4af..3820213 100644
--- a/arch/powerpc/kernel/vdso64/gettimeofday.S
+++ b/arch/powerpc/kernel/vdso64/gettimeofday.S
@@ -145,7 +145,7 @@ V_FUNCTION_BEGIN(__kernel_clock_getres)
bne cr0,99f
li r3,0
- cmpli cr0,r4,0
+ cmpldi cr0,r4,0
crclr cr0*4+so
beqlr
lis r5,CLOCK_REALTIME_RES@h
--
2.7.4
