From 49fd5f5ac4b59dcd53b5788d56d4ae7a8a1e1434 Mon Sep 17 00:00:00 2001 From: Oleg Nesterov Date: Mon, 26 Feb 2024 17:56:47 +0100 Subject: get_signal: don't abuse ksig->info.si_signo and ksig->sig Patch series "get_signal: minor cleanups and fix". Lets remove this clear_siginfo() right now. It is incomplete (and thus looks confusing) and unnecessary. Also, PF_USER_WORKER's already don't get a fully initialized ksig anyway. This patch (of 3): Cleanup and preparation for the next changes. get_signal() uses signr or ksig->info.si_signo or ksig->sig in a chaotic way, this looks confusing. Change it to always use signr. Link: https://lkml.kernel.org/r/20240226165612.GA20787@redhat.com Link: https://lkml.kernel.org/r/20240226165647.GA20826@redhat.com Signed-off-by: Oleg Nesterov Cc: Christian Brauner Cc: Eric W. Biederman Cc: Peter Collingbourne Cc: Wen Yang Signed-off-by: Andrew Morton --- kernel/signal.c | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-) (limited to 'kernel/signal.c') diff --git a/kernel/signal.c b/kernel/signal.c index c9c57d053ce4..09a6dd07cf6b 100644 --- a/kernel/signal.c +++ b/kernel/signal.c @@ -2842,7 +2842,7 @@ relock: spin_lock_irq(&sighand->siglock); } - if (likely(do_signal_stop(ksig->info.si_signo))) { + if (likely(do_signal_stop(signr))) { /* It released the siglock. */ goto relock; } @@ -2866,7 +2866,7 @@ relock: if (sig_kernel_coredump(signr)) { if (print_fatal_signals) - print_fatal_signal(ksig->info.si_signo); + print_fatal_signal(signr); proc_coredump_connector(current); /* * If it was able to dump core, this kills all @@ -2890,7 +2890,7 @@ relock: /* * Death signals, no core dump. */ - do_group_exit(ksig->info.si_signo); + do_group_exit(signr); /* NOTREACHED */ } spin_unlock_irq(&sighand->siglock); @@ -2900,7 +2900,7 @@ out: if (!(ksig->ka.sa.sa_flags & SA_EXPOSE_TAGBITS)) hide_si_addr_tag_bits(ksig); - return ksig->sig > 0; + return signr > 0; } /** -- cgit v1.2.3 From dd69edd643a8263f9a96d0a3a82d8d50d9df9b48 Mon Sep 17 00:00:00 2001 From: Oleg Nesterov Date: Mon, 26 Feb 2024 17:56:50 +0100 Subject: get_signal: hide_si_addr_tag_bits: fix the usage of uninitialized ksig ksig->ka and ksig->info are not initialized if get_signal() returns 0 or if the caller is PF_USER_WORKER. Check signr != 0 before SA_EXPOSE_TAGBITS and move the "out" label down. The latter means that ksig->sig won't be initialized if a PF_USER_WORKER thread gets a fatal signal but this is fine, PF_USER_WORKER's don't use ksig. And there is nothing new, in this case ksig->ka and ksig-info are not initialized anyway. Add a comment. Link: https://lkml.kernel.org/r/20240226165650.GA20829@redhat.com Signed-off-by: Oleg Nesterov Cc: Christian Brauner Cc: Eric W. Biederman Cc: Peter Collingbourne Cc: Wen Yang Signed-off-by: Andrew Morton --- kernel/signal.c | 11 ++++++----- 1 file changed, 6 insertions(+), 5 deletions(-) (limited to 'kernel/signal.c') diff --git a/kernel/signal.c b/kernel/signal.c index 09a6dd07cf6b..a69d3069067a 100644 --- a/kernel/signal.c +++ b/kernel/signal.c @@ -2881,8 +2881,9 @@ relock: /* * PF_USER_WORKER threads will catch and exit on fatal signals - * themselves. They have cleanup that must be performed, so - * we cannot call do_exit() on their behalf. + * themselves. They have cleanup that must be performed, so we + * cannot call do_exit() on their behalf. Note that ksig won't + * be properly initialized, PF_USER_WORKER's shouldn't use it. */ if (current->flags & PF_USER_WORKER) goto out; @@ -2894,12 +2895,12 @@ relock: /* NOTREACHED */ } spin_unlock_irq(&sighand->siglock); -out: + ksig->sig = signr; - if (!(ksig->ka.sa.sa_flags & SA_EXPOSE_TAGBITS)) + if (signr && !(ksig->ka.sa.sa_flags & SA_EXPOSE_TAGBITS)) hide_si_addr_tag_bits(ksig); - +out: return signr > 0; } -- cgit v1.2.3 From a436184e3bfb14b3c38e6ed0c2e7f6d810312c4f Mon Sep 17 00:00:00 2001 From: Oleg Nesterov Date: Mon, 26 Feb 2024 17:56:53 +0100 Subject: get_signal: don't initialize ksig->info if SIGNAL_GROUP_EXIT/group_exec_task This initialization is incomplete and unnecessary, neither do_group_exit() nor PF_USER_WORKER need ksig->info. Link: https://lkml.kernel.org/r/20240226165653.GA20834@redhat.com Signed-off-by: Oleg Nesterov Cc: Christian Brauner Cc: Eric W. Biederman Cc: Peter Collingbourne Cc: Wen Yang Signed-off-by: Andrew Morton --- kernel/signal.c | 9 ++++++--- 1 file changed, 6 insertions(+), 3 deletions(-) (limited to 'kernel/signal.c') diff --git a/kernel/signal.c b/kernel/signal.c index a69d3069067a..9c6a5ccac328 100644 --- a/kernel/signal.c +++ b/kernel/signal.c @@ -2727,12 +2727,15 @@ relock: /* Has this task already been marked for death? */ if ((signal->flags & SIGNAL_GROUP_EXIT) || signal->group_exec_task) { - clear_siginfo(&ksig->info); - ksig->info.si_signo = signr = SIGKILL; + signr = SIGKILL; sigdelset(¤t->pending.signal, SIGKILL); trace_signal_deliver(SIGKILL, SEND_SIG_NOINFO, - &sighand->action[SIGKILL - 1]); + &sighand->action[SIGKILL-1]); recalc_sigpending(); + /* + * implies do_group_exit() or return to PF_USER_WORKER, + * no need to initialize ksig->info/etc. + */ goto fatal; } -- cgit v1.2.3