4.9-stable review patch. If anyone has any objections, please let me know. ------------------ From: Stas Sergeev <stsp@xxxxxxx> commit 441398d378f29a5ad6d0fcda07918e54e4961800 upstream. Currently SS_AUTODISARM is not supported in compatibility mode, but does not return -EINVAL either. This makes dosemu built with -m32 on x86_64 to crash. Also the kernel's sigaltstack selftest fails if compiled with -m32. This patch adds the needed support. Link: http://lkml.kernel.org/r/20170205101213.8163-2-stsp@xxxxxxx Signed-off-by: Stas Sergeev <stsp@xxxxxxxxxxxxxxxxxxxxx> Cc: Milosz Tanski <milosz@xxxxxxxxx> Cc: Andy Lutomirski <luto@xxxxxxxxxx> Cc: Al Viro <viro@xxxxxxxxxxxxxxxxxx> Cc: Arnd Bergmann <arnd@xxxxxxxx> Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx> Cc: Ingo Molnar <mingo@xxxxxxxxxx> Cc: Oleg Nesterov <oleg@xxxxxxxxxx> Cc: Nicolas Pitre <nicolas.pitre@xxxxxxxxxx> Cc: Waiman Long <Waiman.Long@xxxxxxx> Cc: Dave Hansen <dave.hansen@xxxxxxxxxxxxxxx> Cc: Dmitry Safonov <dsafonov@xxxxxxxxxxxxx> Cc: Wang Xiaoqiang <wangxq10@xxxxxxxxxx> Cc: Oleg Nesterov <oleg@xxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> Signed-off-by: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- include/linux/compat.h | 4 +++- kernel/signal.c | 11 +++++++++-- 2 files changed, 12 insertions(+), 3 deletions(-) --- a/include/linux/compat.h +++ b/include/linux/compat.h @@ -711,8 +711,10 @@ int __compat_save_altstack(compat_stack_ compat_stack_t __user *__uss = uss; \ struct task_struct *t = current; \ put_user_ex(ptr_to_compat((void __user *)t->sas_ss_sp), &__uss->ss_sp); \ - put_user_ex(sas_ss_flags(sp), &__uss->ss_flags); \ + put_user_ex(t->sas_ss_flags, &__uss->ss_flags); \ put_user_ex(t->sas_ss_size, &__uss->ss_size); \ + if (t->sas_ss_flags & SS_AUTODISARM) \ + sas_ss_reset(t); \ } while (0); asmlinkage long compat_sys_sched_rr_get_interval(compat_pid_t pid, --- a/kernel/signal.c +++ b/kernel/signal.c @@ -3226,10 +3226,17 @@ int compat_restore_altstack(const compat int __compat_save_altstack(compat_stack_t __user *uss, unsigned long sp) { + int err; struct task_struct *t = current; - return __put_user(ptr_to_compat((void __user *)t->sas_ss_sp), &uss->ss_sp) | - __put_user(sas_ss_flags(sp), &uss->ss_flags) | + err = __put_user(ptr_to_compat((void __user *)t->sas_ss_sp), + &uss->ss_sp) | + __put_user(t->sas_ss_flags, &uss->ss_flags) | __put_user(t->sas_ss_size, &uss->ss_size); + if (err) + return err; + if (t->sas_ss_flags & SS_AUTODISARM) + sas_ss_reset(t); + return 0; } #endif