Index: sys/kern/subr_syscall.c
===================================================================
--- sys/kern/subr_syscall.c
+++ sys/kern/subr_syscall.c
@@ -260,9 +260,14 @@
 		 * the exec event now and then clear TDB_EXEC so that
 		 * the next stop is reported as a syscall exit by
 		 * linux_ptrace_status().
+		 *
+		 * We are accessing p->p_pptr without any additional
+		 * locks here: it cannot change while p is kept locked,
+		 * and a debugger process changing its ABI while tracing
+		 * another process seems highly unprobable.
 		 */
-		if ((td->td_dbgflags & TDB_EXEC) != 0 &&
-		    SV_PROC_ABI(td->td_proc) == SV_ABI_LINUX) {
+		if (traced && (td->td_dbgflags & TDB_EXEC) != 0 &&
+		    SV_PROC_ABI(p->p_pptr) == SV_ABI_LINUX) {
 			ptracestop(td, SIGTRAP, NULL);
 			td->td_dbgflags &= ~TDB_EXEC;
 		}