From: Eric W. Biederman ebiederm@xmission.com
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@ellerman.id.au Cc: Benjamin Herrenschmidt benh@kernel.crashing.org Cc: Paul Mackerras paulus@samba.org 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 ebiederm@xmission.com Cc: Thomas Backlund tmb@iki.fi Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- 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();