On 01/21, Oleg Nesterov wrote: > > On 01/21, Linus Torvalds wrote: > > > > I guess that works then. It's a bit sad, but at least I see why you did it. > > OK, please see v3 rebased on top of "unexport ptrace_check_attach()" you > already applied. > > I tried to update the comment in ptrace_check_attach(), and changed unfreeze() > to simply do WARN_ON() without if/return.
Damn. But the current "if (request != PTRACE_DETACH)" is not right, somehow I forgot that it can fail. I am sending "[PATCH v4 2/3]" in reply to 2/3. Or see the fixlet below. And perhaps you were right, ptrace_unfreeze_traced() should prevent the attach-after-detach race itself... but iiuc then it needs the full mb(), rmb() if not enough for transitivity. Sorry for confusion. Oleg. ------------------------------------------------------------------------------ [PATCH v3 4/3] ptrace: if PTRACE_DETACH fails we need ptrace_unfreeze_traced() Somehow I forgot that PTRACE_DETACH can fail if !valid_signal(data). Fix the check before ptrace_unfreeze_traced(). Signed-off-by: Oleg Nesterov <[email protected]> --- kernel/ptrace.c | 4 ++-- 1 files changed, 2 insertions(+), 2 deletions(-) diff --git a/kernel/ptrace.c b/kernel/ptrace.c index b6c22b5..6cbeaae 100644 --- a/kernel/ptrace.c +++ b/kernel/ptrace.c @@ -939,7 +939,7 @@ SYSCALL_DEFINE4(ptrace, long, request, long, pid, unsigned long, addr, goto out_put_task_struct; ret = arch_ptrace(child, request, addr, data); - if (request != PTRACE_DETACH) + if (ret || request != PTRACE_DETACH) ptrace_unfreeze_traced(child); out_put_task_struct: @@ -1082,7 +1082,7 @@ asmlinkage long compat_sys_ptrace(compat_long_t request, compat_long_t pid, request == PTRACE_INTERRUPT); if (!ret) { ret = compat_arch_ptrace(child, request, addr, data); - if (request != PTRACE_DETACH) + if (ret || request != PTRACE_DETACH) ptrace_unfreeze_traced(child); } -- 1.5.5.1 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
