diff options
| author | Anton Blanchard <anton@samba.org> | 2016-09-25 17:16:53 +1000 |
|---|---|---|
| committer | Michael Ellerman <mpe@ellerman.id.au> | 2016-09-29 15:17:57 +1000 |
| commit | 5045ea37377ce8cca6890d32b127ad6770e6dce5 (patch) | |
| tree | 555065c83a0439cc48bcf9bd41ce1296213995e8 | |
| parent | 2e5bbb5461f138cac631fe21b4ad956feabfba22 (diff) | |
| download | linux-5045ea37377ce8cca6890d32b127ad6770e6dce5.tar.bz2 | |
powerpc/vdso64: Use double word compare on pointers
__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.
Fixes: a7f290dad32e ("[PATCH] powerpc: Merge vdso's and add vdso support to 32 bits kernel")
Cc: stable@vger.kernel.org # v2.6.15+
Signed-off-by: Anton Blanchard <anton@samba.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
| -rw-r--r-- | arch/powerpc/kernel/vdso64/datapage.S | 2 | ||||
| -rw-r--r-- | 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 184a6ba7f283..abf17feffe40 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 a76b4af37ef2..382021324883 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 |