From 83a1f27ad773b1d8f0460d3a676114c7651918cc Mon Sep 17 00:00:00 2001 From: "Eric W. Biederman" Date: Wed, 20 Oct 2021 12:43:53 -0500 Subject: [PATCH] signal/powerpc: On swapcontext failure force SIGSEGV 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 Cc: Benjamin Herrenschmidt Cc: Paul Mackerras Cc: linuxppc-dev@lists.ozlabs.org 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@xmission.com Signed-off-by: Eric W. Biederman --- arch/powerpc/kernel/signal_32.c | 6 ++++-- arch/powerpc/kernel/signal_64.c | 9 ++++++--- 2 files changed, 10 insertions(+), 5 deletions(-) diff --git a/arch/powerpc/kernel/signal_32.c b/arch/powerpc/kernel/signal_32.c index 0608581967f0..666f3da41232 100644 --- a/arch/powerpc/kernel/signal_32.c +++ b/arch/powerpc/kernel/signal_32.c @@ -1062,8 +1062,10 @@ SYSCALL_DEFINE3(swapcontext, struct ucontext __user *, old_ctx, * 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; diff --git a/arch/powerpc/kernel/signal_64.c b/arch/powerpc/kernel/signal_64.c index 1831bba0582e..d8de622c9e4a 100644 --- a/arch/powerpc/kernel/signal_64.c +++ b/arch/powerpc/kernel/signal_64.c @@ -703,15 +703,18 @@ SYSCALL_DEFINE3(swapcontext, struct ucontext __user *, old_ctx, * 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(); -- 2.11.0