Re: [PATCH] s390: ensure that syscall arguments are properly masked on s390

From: Paul Moore <paul(a)paul-moore.com&gt; When executing s390 code on s390x the syscall arguments are not properly masked, leading to some malformed audit records. Signed-off-by: Paul Moore <paul(a)paul-moore.com&gt; --- arch/s390/kernel/ptrace.c | 11 ++++++++--- 1 file changed, 8 insertions(+), 3 deletions(-)

diff --git a/arch/s390/kernel/ptrace.c b/arch/s390/kernel/ptrace.c index 49b1c13..ac1dc74 100644 --- a/arch/s390/kernel/ptrace.c +++ b/arch/s390/kernel/ptrace.c @@ -822,6 +822,7 @@ long compat_arch_ptrace(struct task_struct *child, compat_long_t request, asmlinkage long do_syscall_trace_enter(struct pt_regs *regs) { long ret = 0; + unsigned long mask = -1UL; /* Do the secure computing check first. */ if (secure_computing()) { @@ -849,9 +850,13 @@ asmlinkage long do_syscall_trace_enter(struct pt_regs *regs) if (unlikely(test_thread_flag(TIF_SYSCALL_TRACEPOINT))) trace_sys_enter(regs, regs->gprs[2]); - audit_syscall_entry(regs->gprs[2], regs->orig_gpr2, - regs->gprs[3], regs->gprs[4], - regs->gprs[5]); +#ifdef CONFIG_COMPAT + if (test_thread_flag(TIF_31BIT)) + mask = 0xffffffff; +#endif + audit_syscall_entry(regs->gprs[2], regs->orig_gpr2 & mask, + regs->gprs[3] & mask, regs->gprs[4] & mask, + regs->gprs[5] & mask); out: return ret ?: regs->gprs[2]; }