ACK: [SRU][Xenial][PATCH 0/2] arm64: sigaltstack fails with MINSIGSTKSZ for 32-bit processes (LP: #1844155)

[Connor Kuehl]

On 10/1/19 10:56 AM, Juerg Haefliger wrote:
> [Impact]
> 
> The arm64 kernel allows one to run aarch32 processes on an aarch64 processor, using the standard 32/64-bit syscall compatibility. However this compat layer does not correctly validate the arguments of the sigaltstack syscall which can result in process failures.
> 
> [Test Case]
> 
> The simple reproducer from https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=904385 triggers a memory allocation error with the current Xenial 4.4 kernel.
> 
> [Fix]
> 
> Backport the following two upstream commits:
> 24951465cbd2 arm64: compat: Provide definition for COMPAT_SIGMINSTKSZ
> 22839869f21a signal: Introduce COMPAT_SIGMINSTKSZ for use in compat_sys_sigaltstack
> 
> With these two commits, the reproducer no longer fails.
> 
> [Regression Potential]
> 
> Low. The modifications are trivial and the two patches have been in upstream for quite a while.
> 
> Will Deacon (2):
>    signal: Introduce COMPAT_SIGMINSTKSZ for use in compat_sys_sigaltstack
>    arm64: compat: Provide definition for COMPAT_SIGMINSTKSZ
> 
>   arch/arm64/include/asm/compat.h |  1 +
>   include/linux/compat.h          |  3 +++
>   kernel/signal.c                 | 14 +++++++++-----
>   3 files changed, 13 insertions(+), 5 deletions(-)
> 

Acked-by: Connor Kuehl <connor.kuehl at canonical.com>