[15/39] [S390] ptrace: fix return value of do_syscall_trace_enter()
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From: Greg KH on 24 May 2010 19:30 2.6.33-stable review patch. If anyone has any objections, please let us know. ------------------ From: Gerald Schaefer <gerald.schaefer(a)de.ibm.com> commit 545c174d1f093a462b4bb9131b23d5ea72a600e1 upstream. 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(). Signed-off-by: Gerald Schaefer <gerald.schaefer(a)de.ibm.com> Signed-off-by: Martin Schwidefsky <schwidefsky(a)de.ibm.com> Signed-off-by: Greg Kroah-Hartman <gregkh(a)suse.de> --- arch/s390/kernel/ptrace.c | 5 ++--- 1 file changed, 2 insertions(+), 3 deletions(-) --- a/arch/s390/kernel/ptrace.c +++ b/arch/s390/kernel/ptrace.c @@ -640,7 +640,7 @@ long compat_arch_ptrace(struct task_stru 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(s * 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(s 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) -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo(a)vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/ |