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Commit 545c174d authored by Gerald Schaefer's avatar Gerald Schaefer Committed by Martin Schwidefsky
Browse files

[S390] ptrace: fix return value of do_syscall_trace_enter() 



strace may change the system call number, so regs->gprs[2] must not
be read before tracehook_report_syscall_entry(). This fixes a bug
where "strace -f" will hang after a vfork().

Cc: <stable@kernel.org>
Signed-off-by: default avatarGerald Schaefer <gerald.schaefer@de.ibm.com>
Signed-off-by: default avatarMartin Schwidefsky <schwidefsky@de.ibm.com>
parent 1c1e093c

arch/s390/kernel/ptrace.c

+2 −3
Original line number Diff line number Diff line
@@ -640,7 +640,7 @@ long compat_arch_ptrace(struct task_struct *child, compat_long_t request, 


asmlinkage long do_syscall_trace_enter(struct pt_regs *regs)

{

	long ret;

	long ret = 0;



	/* Do the secure computing check first. */

	secure_computing(regs->gprs[2]);
@@ -649,7 +649,6 @@ asmlinkage long do_syscall_trace_enter(struct pt_regs *regs) 
	 * The sysc_tracesys code in entry.S stored the system

	 * call number to gprs[2].

	 */

	ret = regs->gprs[2];

	if (test_thread_flag(TIF_SYSCALL_TRACE) &&

	    (tracehook_report_syscall_entry(regs) ||

	     regs->gprs[2] >= NR_syscalls)) {
@@ -671,7 +670,7 @@ asmlinkage long do_syscall_trace_enter(struct pt_regs *regs) 
				    regs->gprs[2], regs->orig_gpr2,

				    regs->gprs[3], regs->gprs[4],

				    regs->gprs[5]);

	return ret;

	return ret ?: regs->gprs[2];

}



asmlinkage void do_syscall_trace_exit(struct pt_regs *regs)