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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: a7f290dad3
("[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>
This commit is contained in:
parent
2e5bbb5461
commit
5045ea3737
2 changed files with 2 additions and 2 deletions
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@ -59,7 +59,7 @@ V_FUNCTION_BEGIN(__kernel_get_syscall_map)
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bl V_LOCAL_FUNC(__get_datapage)
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mtlr r12
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addi r3,r3,CFG_SYSCALL_MAP64
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cmpli cr0,r4,0
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cmpldi cr0,r4,0
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crclr cr0*4+so
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beqlr
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li r0,NR_syscalls
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@ -145,7 +145,7 @@ V_FUNCTION_BEGIN(__kernel_clock_getres)
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bne cr0,99f
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li r3,0
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cmpli cr0,r4,0
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cmpldi cr0,r4,0
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crclr cr0*4+so
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beqlr
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lis r5,CLOCK_REALTIME_RES@h
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