This is a note to let you know that I've just added the patch titled signal/powerpc: On swapcontext failure force SIGSEGV to the 5.15-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: signal-powerpc-on-swapcontext-failure-force-sigsegv.patch and it can be found in the queue-5.15 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable@xxxxxxxxxxxxxxx> know about it. >From 83a1f27ad773b1d8f0460d3a676114c7651918cc Mon Sep 17 00:00:00 2001 From: "Eric W. Biederman" <ebiederm@xxxxxxxxxxxx> Date: Wed, 20 Oct 2021 12:43:53 -0500 Subject: signal/powerpc: On swapcontext failure force SIGSEGV From: Eric W. Biederman <ebiederm@xxxxxxxxxxxx> commit 83a1f27ad773b1d8f0460d3a676114c7651918cc upstream. If the register state may be partial and corrupted instead of calling do_exit, call force_sigsegv(SIGSEGV). Which properly kills the process with SIGSEGV and does not let any more userspace code execute, instead of just killing one thread of the process and potentially confusing everything. Cc: Michael Ellerman <mpe@xxxxxxxxxxxxxx> Cc: Benjamin Herrenschmidt <benh@xxxxxxxxxxxxxxxxxxx> Cc: Paul Mackerras <paulus@xxxxxxxxx> Cc: linuxppc-dev@xxxxxxxxxxxxxxxx History-tree: git://git.kernel.org/pub/scm/linux/kernel/git/tglx/history.git Fixes: 756f1ae8a44e ("PPC32: Rework signal code and add a swapcontext system call.") Fixes: 04879b04bf50 ("[PATCH] ppc64: VMX (Altivec) support & signal32 rework, from Ben Herrenschmidt") Link: https://lkml.kernel.org/r/20211020174406.17889-7-ebiederm@xxxxxxxxxxxx Signed-off-by: Eric W. Biederman <ebiederm@xxxxxxxxxxxx> Cc: Thomas Backlund <tmb@xxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- arch/powerpc/kernel/signal_32.c | 6 ++++-- arch/powerpc/kernel/signal_64.c | 9 ++++++--- 2 files changed, 10 insertions(+), 5 deletions(-) --- a/arch/powerpc/kernel/signal_32.c +++ b/arch/powerpc/kernel/signal_32.c @@ -1062,8 +1062,10 @@ SYSCALL_DEFINE3(swapcontext, struct ucon * or if another thread unmaps the region containing the context. * We kill the task with a SIGSEGV in this situation. */ - if (do_setcontext(new_ctx, regs, 0)) - do_exit(SIGSEGV); + if (do_setcontext(new_ctx, regs, 0)) { + force_sigsegv(SIGSEGV); + return -EFAULT; + } set_thread_flag(TIF_RESTOREALL); return 0; --- a/arch/powerpc/kernel/signal_64.c +++ b/arch/powerpc/kernel/signal_64.c @@ -703,15 +703,18 @@ SYSCALL_DEFINE3(swapcontext, struct ucon * We kill the task with a SIGSEGV in this situation. */ - if (__get_user_sigset(&set, &new_ctx->uc_sigmask)) - do_exit(SIGSEGV); + if (__get_user_sigset(&set, &new_ctx->uc_sigmask)) { + force_sigsegv(SIGSEGV); + return -EFAULT; + } set_current_blocked(&set); if (!user_read_access_begin(new_ctx, ctx_size)) return -EFAULT; if (__unsafe_restore_sigcontext(current, NULL, 0, &new_ctx->uc_mcontext)) { user_read_access_end(); - do_exit(SIGSEGV); + force_sigsegv(SIGSEGV); + return -EFAULT; } user_read_access_end(); Patches currently in stable-queue which might be from ebiederm@xxxxxxxxxxxx are queue-5.15/signal-vm86_32-properly-send-sigsegv-when-the-vm86-state-cannot-be-saved.patch queue-5.15/signal-don-t-always-set-sa_immutable-for-forced-signals.patch queue-5.15/signal-x86-in-emulate_vsyscall-force-a-signal-instead-of-calling-do_exit.patch queue-5.15/ipc-warn-if-trying-to-remove-ipc-object-which-is-absent.patch queue-5.15/signal-replace-force_sigsegv-sigsegv-with-force_fatal_sig-sigsegv.patch queue-5.15/signal-powerpc-on-swapcontext-failure-force-sigsegv.patch queue-5.15/exit-syscall_user_dispatch-send-ordinary-signals-on-failure.patch queue-5.15/signal-s390-use-force_sigsegv-in-default_trap_handler.patch queue-5.15/signal-implement-force_fatal_sig.patch queue-5.15/signal-sparc32-in-setup_rt_frame-and-setup_fram-use-force_fatal_sig.patch queue-5.15/signal-sparc32-exit-with-a-fatal-signal-when-try_to_clear_window_buffer-fails.patch queue-5.15/shm-extend-forced-shm-destroy-to-support-objects-from-several-ipc-nses.patch queue-5.15/signal-replace-force_fatal_sig-with-force_exit_sig-when-in-doubt.patch