diff options
Diffstat (limited to 'arch/arc/kernel/signal.c')
| -rw-r--r-- | arch/arc/kernel/signal.c | 45 |
1 files changed, 29 insertions, 16 deletions
diff --git a/arch/arc/kernel/signal.c b/arch/arc/kernel/signal.c index ee6ef2f60a28..6763654239a2 100644 --- a/arch/arc/kernel/signal.c +++ b/arch/arc/kernel/signal.c @@ -101,7 +101,6 @@ SYSCALL_DEFINE0(rt_sigreturn) { struct rt_sigframe __user *sf; unsigned int magic; - int err; struct pt_regs *regs = current_pt_regs(); /* Always make any pending restarted system calls return -EINTR */ @@ -119,18 +118,28 @@ SYSCALL_DEFINE0(rt_sigreturn) if (!access_ok(VERIFY_READ, sf, sizeof(*sf))) goto badframe; - err = restore_usr_regs(regs, sf); - err |= __get_user(magic, &sf->sigret_magic); - if (err) + if (__get_user(magic, &sf->sigret_magic)) goto badframe; if (unlikely(is_do_ss_needed(magic))) if (restore_altstack(&sf->uc.uc_stack)) goto badframe; + if (restore_usr_regs(regs, sf)) + goto badframe; + /* Don't restart from sigreturn */ syscall_wont_restart(regs); + /* + * Ensure that sigreturn always returns to user mode (in case the + * regs saved on user stack got fudged between save and sigreturn) + * Otherwise it is easy to panic the kernel with a custom + * signal handler and/or restorer which clobberes the status32/ret + * to return to a bogus location in kernel mode. + */ + regs->status32 |= STATUS_U_MASK; + return regs->r0; badframe: @@ -191,6 +200,15 @@ setup_rt_frame(int signo, struct k_sigaction *ka, siginfo_t *info, return 1; /* + * w/o SA_SIGINFO, struct ucontext is partially populated (only + * uc_mcontext/uc_sigmask) for kernel's normal user state preservation + * during signal handler execution. This works for SA_SIGINFO as well + * although the semantics are now overloaded (the same reg state can be + * inspected by userland: but are they allowed to fiddle with it ? + */ + err |= stash_usr_regs(sf, regs, set); + + /* * SA_SIGINFO requires 3 args to signal handler: * #1: sig-no (common to any handler) * #2: struct siginfo @@ -213,14 +231,6 @@ setup_rt_frame(int signo, struct k_sigaction *ka, siginfo_t *info, magic = MAGIC_SIGALTSTK; } - /* - * w/o SA_SIGINFO, struct ucontext is partially populated (only - * uc_mcontext/uc_sigmask) for kernel's normal user state preservation - * during signal handler execution. This works for SA_SIGINFO as well - * although the semantics are now overloaded (the same reg state can be - * inspected by userland: but are they allowed to fiddle with it ? - */ - err |= stash_usr_regs(sf, regs, set); err |= __put_user(magic, &sf->sigret_magic); if (err) return err; @@ -233,8 +243,11 @@ setup_rt_frame(int signo, struct k_sigaction *ka, siginfo_t *info, /* * handler returns using sigreturn stub provided already by userpsace + * If not, nuke the process right away */ - BUG_ON(!(ka->sa.sa_flags & SA_RESTORER)); + if(!(ka->sa.sa_flags & SA_RESTORER)) + return 1; + regs->blink = (unsigned long)ka->sa.sa_restorer; /* User Stack for signal handler will be above the frame just carved */ @@ -301,12 +314,12 @@ handle_signal(unsigned long sig, struct k_sigaction *ka, siginfo_t *info, struct pt_regs *regs) { sigset_t *oldset = sigmask_to_save(); - int ret; + int failed; /* Set up the stack frame */ - ret = setup_rt_frame(sig, ka, info, oldset, regs); + failed = setup_rt_frame(sig, ka, info, oldset, regs); - if (ret) + if (failed) force_sigsegv(sig, current); else signal_delivered(sig, info, ka, regs, 0); |