From 94c80b2598dbd2b8a6fe5f5c2c3af1beb37f66c7 Mon Sep 17 00:00:00 2001 From: Bodo Stroesser Date: Sat, 3 Sep 2005 15:57:13 -0700 Subject: [PATCH] [PATCH] Ptrace/i386: fix "syscall audit" interaction with singlestep Paolo 'Blaisorblade' Giarrusso Avoid giving two traps for singlestep instead of one, when syscall auditing is enabled. In fact no singlestep trap is sent on syscall entry, only on syscall exit, as can be seen in entry.S: # Note that in this mask _TIF_SINGLESTEP is not tested !!! <<<<<<<<<<<<<< testb $(_TIF_SYSCALL_TRACE|_TIF_SYSCALL_AUDIT|_TIF_SECCOMP),TI_flags(%ebp) jnz syscall_trace_entry ... syscall_trace_entry: ... call do_syscall_trace But auditing a SINGLESTEP'ed process causes do_syscall_trace to be called, so the tracer will get one more trap on the syscall entry path, which it shouldn't. Signed-off-by: Paolo 'Blaisorblade' Giarrusso CC: Roland McGrath Cc: Jeff Dike Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- arch/i386/kernel/ptrace.c | 15 +++++++++++++-- 1 file changed, 13 insertions(+), 2 deletions(-) diff --git a/arch/i386/kernel/ptrace.c b/arch/i386/kernel/ptrace.c index 0da59b4..5ee9e1d 100644 --- a/arch/i386/kernel/ptrace.c +++ b/arch/i386/kernel/ptrace.c @@ -683,8 +683,19 @@ void do_syscall_trace(struct pt_regs *regs, int entryexit) /* do the secure computing check first */ secure_computing(regs->orig_eax); - if (unlikely(current->audit_context) && entryexit) - audit_syscall_exit(current, AUDITSC_RESULT(regs->eax), regs->eax); + if (unlikely(current->audit_context)) { + if (entryexit) + audit_syscall_exit(current, AUDITSC_RESULT(regs->eax), regs->eax); + + /* Debug traps, when using PTRACE_SINGLESTEP, must be sent only + * on the syscall exit path. Normally, when TIF_SYSCALL_AUDIT is + * not used, entry.S will call us only on syscall exit, not + * entry ; so when TIF_SYSCALL_AUDIT is used we must avoid + * calling send_sigtrap() on syscall entry. + */ + else if (is_singlestep) + goto out; + } if (!(current->ptrace & PT_PTRACED)) goto out; -- 2.7.4