[PATCH] arm: clone: restore stack pointer just after return from syscall

Carmelo AMOROSO carmelo.amoroso at st.com
Tue Dec 11 15:39:34 UTC 2012


On 11/12/2012 16.32, Filippo ARCIDIACONO wrote:
> If the syscall returns with an error the stack pointer and r4 register
> are not restored because the instruction 'ldmnefd sp!, {r4}' is executed
> after branching to '__error' label.
> This bug has been spotted out by running './utstest clone 5' from LTP
> built with -fstack-protector-all compiler flag as log below:
> 
> root at cortex-a9:/usr/tests/ltp/testcases/bin# ./utstest clone 5
> stack smashing detected: ./utstest terminated()
> 
> Regression introduced by commit e58798e107d652644629a1daaa95d76430808d53
> 
> Signed-off-by: Filippo Arcidiacono <filippo.arcidiacono at st.com>
> Signed-off-by: Giuseppe Di Giore <giuseppe.di-giore at st.com>
> ---
>  libc/sysdeps/linux/arm/clone.S |    2 +-
>  1 files changed, 1 insertions(+), 1 deletions(-)
> 
> diff --git a/libc/sysdeps/linux/arm/clone.S b/libc/sysdeps/linux/arm/clone.S
> index fdc05b8..e4101ba 100644
> --- a/libc/sysdeps/linux/arm/clone.S
> +++ b/libc/sysdeps/linux/arm/clone.S
> @@ -111,8 +111,8 @@ __clone:
>  	ldr	r4, [sp, #12]
>  	DO_CALL (clone)
>  	movs	a1, a1
> -	blt	__error
>  	ldmnefd	sp!, {r4}
> +	blt	__error
>  	IT(t, ne)
>  #if defined(__USE_BX__)
>  	bxne	lr
> 

sneaky bug. well spotted.

Applied, thanks.
Carmelo



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