The patch titled ptrace: copy_process() should disable stepping has been removed from the -mm tree. Its filename was ptrace-copy_process-should-disable-stepping.patch This patch was dropped because it was merged into mainline or a subsystem tree The current -mm tree may be found at http://userweb.kernel.org/~akpm/mmotm/ ------------------------------------------------------ Subject: ptrace: copy_process() should disable stepping From: Oleg Nesterov <oleg@xxxxxxxxxx> If the tracee calls fork() after PTRACE_SINGLESTEP, the forked child starts with TIF_SINGLESTEP/X86_EFLAGS_TF bits copied from ptraced parent. This is not right, especially when the new child is not auto-attaced: in this case it is killed by SIGTRAP. Change copy_process() to call user_disable_single_step(). Tested on x86. Test-case: #include <stdio.h> #include <unistd.h> #include <signal.h> #include <sys/ptrace.h> #include <sys/wait.h> #include <assert.h> int main(void) { int pid, status; if (!(pid = fork())) { assert(ptrace(PTRACE_TRACEME) == 0); kill(getpid(), SIGSTOP); if (!fork()) { /* kernel bug: this child will be killed by SIGTRAP */ printf("Hello world\n"); return 43; } wait(&status); return WEXITSTATUS(status); } for (;;) { assert(pid == wait(&status)); if (WIFEXITED(status)) break; assert(ptrace(PTRACE_SINGLESTEP, pid, 0,0) == 0); } assert(WEXITSTATUS(status) == 43); return 0; } Signed-off-by: Oleg Nesterov <oleg@xxxxxxxxxx> Acked-by: Roland McGrath <roland@xxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- kernel/fork.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) diff -puN kernel/fork.c~ptrace-copy_process-should-disable-stepping kernel/fork.c --- a/kernel/fork.c~ptrace-copy_process-should-disable-stepping +++ a/kernel/fork.c @@ -1210,9 +1210,10 @@ static struct task_struct *copy_process( p->sas_ss_sp = p->sas_ss_size = 0; /* - * Syscall tracing should be turned off in the child regardless - * of CLONE_PTRACE. + * Syscall tracing and stepping should be turned off in the + * child regardless of CLONE_PTRACE. */ + user_disable_single_step(p); clear_tsk_thread_flag(p, TIF_SYSCALL_TRACE); #ifdef TIF_SYSCALL_EMU clear_tsk_thread_flag(p, TIF_SYSCALL_EMU); _ Patches currently in -mm which might be from oleg@xxxxxxxxxx are origin.patch do_wait-optimization-do-not-place-sub-threads-on-task_struct-children-list.patch mm-introduce-coredump-parameter-structure.patch linux-next.patch posix-cpu-timers-reset-expire-cache-when-no-timer-is-running.patch -- To unsubscribe from this list: send the line "unsubscribe mm-commits" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html