3 files changed, 188 insertions, 102 deletions

diff --git a/arch/um/os-Linux/registers.c b/arch/um/os-Linux/registers.c
index c78fae3aba81..830fe6a1518a 100644
--- a/arch/um/os-Linux/registers.c
+++ b/arch/um/os-Linux/registers.c
@@ -8,42 +8,41 @@
 #include <string.h>
 #include <sys/ptrace.h>
 #include "sysdep/ptrace.h"
-#include "user.h"
 
-void save_registers(int pid, struct uml_pt_regs *regs)
+int save_registers(int pid, struct uml_pt_regs *regs)
 {
         int err;
 
         err = ptrace(PTRACE_GETREGS, pid, 0, regs->gp);
         if (err < 0)
-                panic("save_registers - saving registers failed, errno = %d\n",
-                      errno);
+                return -errno;
+        return 0;
 }
 
-void restore_registers(int pid, struct uml_pt_regs *regs)
+int restore_registers(int pid, struct uml_pt_regs *regs)
 {
         int err;
 
         err = ptrace(PTRACE_SETREGS, pid, 0, regs->gp);
         if (err < 0)
-                panic("restore_registers - saving registers failed, "
-                      "errno = %d\n", errno);
+                return -errno;
+        return 0;
 }
 
 /* This is set once at boot time and not changed thereafter */
 
 static unsigned long exec_regs[MAX_REG_NR];
 
-void init_registers(int pid)
+int init_registers(int pid)
 {
         int err;
 
         err = ptrace(PTRACE_GETREGS, pid, 0, exec_regs);
-        if (err)
-                panic("check_ptrace : PTRACE_GETREGS failed, errno = %d",
-                      errno);
+        if (err < 0)
+                return -errno;
 
         arch_init_registers(pid);
+        return 0;
 }
 
 void get_safe_registers(unsigned long *regs)
diff --git a/arch/um/os-Linux/skas/process.c b/arch/um/os-Linux/skas/process.c
index 7dc24e3cb190..862fea0290ec 100644
--- a/arch/um/os-Linux/skas/process.c
+++ b/arch/um/os-Linux/skas/process.c
@@ -38,17 +38,17 @@ int is_skas_winch(int pid, int fd, void *data)
 
 static int ptrace_dump_regs(int pid)
 {
-        unsigned long regs[MAX_REG_NR];
-        int i;
+        unsigned long regs[MAX_REG_NR];
+        int i;
 
-        if (ptrace(PTRACE_GETREGS, pid, 0, regs) < 0)
-                return -errno;
+        if (ptrace(PTRACE_GETREGS, pid, 0, regs) < 0)
+                return -errno;
 
         printk(UM_KERN_ERR "Stub registers -\n");
         for (i = 0; i < ARRAY_SIZE(regs); i++)
                 printk(UM_KERN_ERR "\t%d - %lx\n", i, regs[i]);
 
-        return 0;
+        return 0;
 }
 
 /*
@@ -73,9 +73,11 @@ void wait_stub_done(int pid)
                         break;
 
                 err = ptrace(PTRACE_CONT, pid, 0, 0);
-                if (err)
-                        panic("wait_stub_done : continue failed, errno = %d\n",
-                              errno);
+                if (err) {
+                        printk(UM_KERN_ERR "wait_stub_done : continue failed, "
+                               "errno = %d\n", errno);
+                        fatal_sigsegv();
+                }
         }
 
         if (((1 << WSTOPSIG(status)) & STUB_DONE_MASK) != 0)
@@ -86,8 +88,10 @@ bad_wait:
         if (err)
                 printk(UM_KERN_ERR "Failed to get registers from stub, "
                        "errno = %d\n", -err);
-        panic("wait_stub_done : failed to wait for SIGUSR1/SIGTRAP, pid = %d, "
-              "n = %d, errno = %d, status = 0x%x\n", pid, n, errno, status);
+        printk(UM_KERN_ERR "wait_stub_done : failed to wait for SIGTRAP, "
+               "pid = %d, n = %d, errno = %d, status = 0x%x\n", pid, n, errno,
+               status);
+        fatal_sigsegv();
 }
 
 extern unsigned long current_stub_stack(void);
@@ -98,9 +102,11 @@ void get_skas_faultinfo(int pid, struct faultinfo * fi)
 
         if (ptrace_faultinfo) {
                 err = ptrace(PTRACE_FAULTINFO, pid, 0, fi);
-                if (err)
-                        panic("get_skas_faultinfo - PTRACE_FAULTINFO failed, "
-                              "errno = %d\n", errno);
+                if (err) {
+                        printk(UM_KERN_ERR "get_skas_faultinfo - "
+                               "PTRACE_FAULTINFO failed, errno = %d\n", errno);
+                        fatal_sigsegv();
+                }
 
                 /* Special handling for i386, which has different structs */
                 if (sizeof(struct ptrace_faultinfo) < sizeof(struct faultinfo))
@@ -110,9 +116,11 @@ void get_skas_faultinfo(int pid, struct faultinfo * fi)
         }
         else {
                 err = ptrace(PTRACE_CONT, pid, 0, SIGSEGV);
-                if (err)
-                        panic("Failed to continue stub, pid = %d, errno = %d\n",
-                              pid, errno);
+                if (err) {
+                        printk(UM_KERN_ERR "Failed to continue stub, pid = %d, "
+                               "errno = %d\n", pid, errno);
+                        fatal_sigsegv();
+                }
                 wait_stub_done(pid);
 
                 /*
@@ -145,25 +153,31 @@ static void handle_trap(int pid, struct uml_pt_regs *regs,
         {
                 err = ptrace(PTRACE_POKEUSR, pid, PT_SYSCALL_NR_OFFSET,
                              __NR_getpid);
-                if (err < 0)
-                        panic("handle_trap - nullifying syscall failed, "
-                              "errno = %d\n", errno);
+                if (err < 0) {
+                        printk(UM_KERN_ERR "handle_trap - nullifying syscall "
+                               "failed, errno = %d\n", errno);
+                        fatal_sigsegv();
+                }
 
                 err = ptrace(PTRACE_SYSCALL, pid, 0, 0);
-                if (err < 0)
-                        panic("handle_trap - continuing to end of syscall "
-                              "failed, errno = %d\n", errno);
+                if (err < 0) {
+                        printk(UM_KERN_ERR "handle_trap - continuing to end of "
+                               "syscall failed, errno = %d\n", errno);
+                        fatal_sigsegv();
+                }
 
                 CATCH_EINTR(err = waitpid(pid, &status, WUNTRACED | __WALL));
                 if ((err < 0) || !WIFSTOPPED(status) ||
-                   (WSTOPSIG(status) != SIGTRAP + 0x80)) {
-                        err = ptrace_dump_regs(pid);
-                        if (err)
-                                printk(UM_KERN_ERR "Failed to get registers "
+                    (WSTOPSIG(status) != SIGTRAP + 0x80)) {
+                        err = ptrace_dump_regs(pid);
+                        if (err)
+                                printk(UM_KERN_ERR "Failed to get registers "
                                        "from process, errno = %d\n", -err);
-                        panic("handle_trap - failed to wait at end of syscall, "
-                              "errno = %d, status = %d\n", errno, status);
-                }
+                        printk(UM_KERN_ERR "handle_trap - failed to wait at "
+                               "end of syscall, errno = %d, status = %d\n",
+                               errno, status);
+                        fatal_sigsegv();
+                }
         }
 
         handle_syscall(regs);
@@ -181,9 +195,11 @@ static int userspace_tramp(void *stack)
         signal(SIGTERM, SIG_DFL);
         signal(SIGWINCH, SIG_IGN);
         err = set_interval();
-        if (err)
-                panic("userspace_tramp - setting timer failed, errno = %d\n",
-                      err);
+        if (err) {
+                printk(UM_KERN_ERR "userspace_tramp - setting timer failed, "
+                       "errno = %d\n", err);
+                exit(1);
+        }
 
         if (!proc_mm) {
                 /*
@@ -226,9 +242,11 @@ static int userspace_tramp(void *stack)
                 sa.sa_flags = SA_ONSTACK | SA_NODEFER;
                 sa.sa_handler = (void *) v;
                 sa.sa_restorer = NULL;
-                if (sigaction(SIGSEGV, &sa, NULL) < 0)
-                        panic("userspace_tramp - setting SIGSEGV handler "
-                              "failed - errno = %d\n", errno);
+                if (sigaction(SIGSEGV, &sa, NULL) < 0) {
+                        printk(UM_KERN_ERR "userspace_tramp - setting SIGSEGV "
+                               "handler failed - errno = %d\n", errno);
+                        exit(1);
+                }
         }
 
         kill(os_getpid(), SIGSTOP);
@@ -244,13 +262,18 @@ int start_userspace(unsigned long stub_stack)
 {
         void *stack;
         unsigned long sp;
-        int pid, status, n, flags;
+        int pid, status, n, flags, err;
 
         stack = mmap(NULL, UM_KERN_PAGE_SIZE,
                      PROT_READ | PROT_WRITE | PROT_EXEC,
                      MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
-        if (stack == MAP_FAILED)
-                panic("start_userspace : mmap failed, errno = %d", errno);
+        if (stack == MAP_FAILED) {
+                err = -errno;
+                printk(UM_KERN_ERR "start_userspace : mmap failed, "
+                       "errno = %d", errno);
+                return err;
+        }
+
         sp = (unsigned long) stack + UM_KERN_PAGE_SIZE - sizeof(void *);
 
         flags = CLONE_FILES;
@@ -260,29 +283,50 @@ int start_userspace(unsigned long stub_stack)
                 flags |= SIGCHLD;
 
         pid = clone(userspace_tramp, (void *) sp, flags, (void *) stub_stack);
-        if (pid < 0)
-                panic("start_userspace : clone failed, errno = %d", errno);
+        if (pid < 0) {
+                err = -errno;
+                printk(UM_KERN_ERR "start_userspace : clone failed, "
+                       "errno = %d", errno);
+                return err;
+        }
 
         do {
                 CATCH_EINTR(n = waitpid(pid, &status, WUNTRACED | __WALL));
-                if (n < 0)
-                        panic("start_userspace : wait failed, errno = %d",
-                              errno);
+                if (n < 0) {
+                        err = -errno;
+                        printk(UM_KERN_ERR "start_userspace : wait failed, "
+                               "errno = %d", errno);
+                        goto out_kill;
+                }
         } while (WIFSTOPPED(status) && (WSTOPSIG(status) == SIGVTALRM));
 
-        if (!WIFSTOPPED(status) || (WSTOPSIG(status) != SIGSTOP))
-                panic("start_userspace : expected SIGSTOP, got status = %d",
-                      status);
+        if (!WIFSTOPPED(status) || (WSTOPSIG(status) != SIGSTOP)) {
+                err = -EINVAL;
+                printk(UM_KERN_ERR "start_userspace : expected SIGSTOP, got "
+                       "status = %d", status);
+                goto out_kill;
+        }
 
         if (ptrace(PTRACE_OLDSETOPTIONS, pid, NULL,
-                   (void *) PTRACE_O_TRACESYSGOOD) < 0)
-                panic("start_userspace : PTRACE_OLDSETOPTIONS failed, "
-                      "errno = %d\n", errno);
+                   (void *) PTRACE_O_TRACESYSGOOD) < 0) {
+                err = -errno;
+                printk(UM_KERN_ERR "start_userspace : PTRACE_OLDSETOPTIONS "
+                       "failed, errno = %d\n", errno);
+                goto out_kill;
+        }
 
-        if (munmap(stack, UM_KERN_PAGE_SIZE) < 0)
-                panic("start_userspace : munmap failed, errno = %d\n", errno);
+        if (munmap(stack, UM_KERN_PAGE_SIZE) < 0) {
+                err = -errno;
+                printk(UM_KERN_ERR "start_userspace : munmap failed, "
+                       "errno = %d\n", errno);
+                goto out_kill;
+        }
 
         return pid;
+
+ out_kill:
+        os_kill_ptraced_process(pid, 1);
+        return err;
 }
 
 void userspace(struct uml_pt_regs *regs)
@@ -300,9 +344,16 @@ void userspace(struct uml_pt_regs *regs)
         nsecs += os_nsecs();
 
         while (1) {
+                /*
+                 * This can legitimately fail if the process loads a
+                 * bogus value into a segment register.  It will
+                 * segfault and PTRACE_GETREGS will read that value
+                 * out of the process.  However, PTRACE_SETREGS will
+                 * fail.  In this case, there is nothing to do but
+                 * just kill the process.
+                 */
                 if (ptrace(PTRACE_SETREGS, pid, 0, regs->gp))
-                        panic("userspace - PTRACE_SETREGS failed, "
-                              "errno = %d\n", errno);
+                        fatal_sigsegv();
 
                 /* Now we set local_using_sysemu to be used for one loop */
                 local_using_sysemu = get_using_sysemu();
@@ -310,21 +361,25 @@ void userspace(struct uml_pt_regs *regs)
                 op = SELECT_PTRACE_OPERATION(local_using_sysemu,
                                              singlestepping(NULL));
 
-                err = ptrace(op, pid, 0, 0);
-                if (err)
-                        panic("userspace - could not resume userspace process, "
-                              "pid=%d, ptrace operation = %d, errno = %d\n",
-                              pid, op, errno);
+                if (ptrace(op, pid, 0, 0)) {
+                        printk(UM_KERN_ERR "userspace - ptrace continue "
+                               "failed, op = %d, errno = %d\n", op, errno);
+                        fatal_sigsegv();
+                }
 
                 CATCH_EINTR(err = waitpid(pid, &status, WUNTRACED | __WALL));
-                if (err < 0)
-                        panic("userspace - waitpid failed, errno = %d\n",
-                              errno);
+                if (err < 0) {
+                        printk(UM_KERN_ERR "userspace - wait failed, "
+                               "errno = %d\n", errno);
+                        fatal_sigsegv();
+                }
 
                 regs->is_user = 1;
-                if (ptrace(PTRACE_GETREGS, pid, 0, regs->gp))
-                        panic("userspace - saving registers failed, "
-                              "errno = %d\n", errno);
+                if (ptrace(PTRACE_GETREGS, pid, 0, regs->gp)) {
+                        printk(UM_KERN_ERR "userspace - PTRACE_GETREGS failed, "
+                               "errno = %d\n", errno);
+                        fatal_sigsegv();
+                }
 
                 UPT_SYSCALL_NR(regs) = -1; /* Assume: It's not a syscall */
 
@@ -371,6 +426,7 @@ void userspace(struct uml_pt_regs *regs)
                         default:
                                 printk(UM_KERN_ERR "userspace - child stopped "
                                        "with signal %d\n", sig);
+                                fatal_sigsegv();
                         }
                         pid = userspace_pid[0];
                         interrupt_end();
@@ -422,9 +478,12 @@ int copy_context_skas0(unsigned long new_stack, int pid)
                                                      .it_interval = tv }) });
 
         err = ptrace_setregs(pid, thread_regs);
-        if (err < 0)
-                panic("copy_context_skas0 : PTRACE_SETREGS failed, "
-                      "pid = %d, errno = %d\n", pid, -err);
+        if (err < 0) {
+                err = -errno;
+                printk(UM_KERN_ERR "copy_context_skas0 : PTRACE_SETREGS "
+                       "failed, pid = %d, errno = %d\n", pid, -err);
+                return err;
+        }
 
         /* set a well known return code for detection of child write failure */
         child_data->err = 12345678;
@@ -434,31 +493,47 @@ int copy_context_skas0(unsigned long new_stack, int pid)
          * parent's stack, and check, if bad result.
          */
         err = ptrace(PTRACE_CONT, pid, 0, 0);
-        if (err)
-                panic("Failed to continue new process, pid = %d, "
-                      "errno = %d\n", pid, errno);
+        if (err) {
+                err = -errno;
+                printk(UM_KERN_ERR "Failed to continue new process, pid = %d, "
+                       "errno = %d\n", pid, errno);
+                return err;
+        }
+
         wait_stub_done(pid);
 
         pid = data->err;
-        if (pid < 0)
-                panic("copy_context_skas0 - stub-parent reports error %d\n",
-                      -pid);
+        if (pid < 0) {
+                printk(UM_KERN_ERR "copy_context_skas0 - stub-parent reports "
+                       "error %d\n", -pid);
+                return pid;
+        }
 
         /*
          * Wait, until child has finished too: read child's result from
          * child's stack and check it.
          */
         wait_stub_done(pid);
-        if (child_data->err != STUB_DATA)
-                panic("copy_context_skas0 - stub-child reports error %ld\n",
-                      child_data->err);
+        if (child_data->err != STUB_DATA) {
+                printk(UM_KERN_ERR "copy_context_skas0 - stub-child reports "
+                       "error %ld\n", child_data->err);
+                err = child_data->err;
+                goto out_kill;
+        }
 
         if (ptrace(PTRACE_OLDSETOPTIONS, pid, NULL,
-                   (void *)PTRACE_O_TRACESYSGOOD) < 0)
-                panic("copy_context_skas0 : PTRACE_OLDSETOPTIONS failed, "
-                      "errno = %d\n", errno);
+                   (void *)PTRACE_O_TRACESYSGOOD) < 0) {
+                err = -errno;
+                printk(UM_KERN_ERR "copy_context_skas0 : PTRACE_OLDSETOPTIONS "
+                       "failed, errno = %d\n", errno);
+                goto out_kill;
+        }
 
         return pid;
+
+ out_kill:
+        os_kill_ptraced_process(pid, 1);
+        return err;
 }
 
 /*
@@ -466,8 +541,8 @@ int copy_context_skas0(unsigned long new_stack, int pid)
  * available. Opening /proc/mm creates a new mm_context, which lacks
  * the stub-pages. Thus, we map them using /proc/mm-fd
  */
-void map_stub_pages(int fd, unsigned long code,
-                    unsigned long data, unsigned long stack)
+int map_stub_pages(int fd, unsigned long code, unsigned long data,
+                   unsigned long stack)
 {
         struct proc_mm_op mmop;
         int n;
@@ -491,8 +566,9 @@ void map_stub_pages(int fd, unsigned long code,
                 printk(UM_KERN_ERR "mmap args - addr = 0x%lx, fd = %d, "
                        "offset = %llx\n", code, code_fd,
                        (unsigned long long) code_offset);
-                panic("map_stub_pages : /proc/mm map for code failed, "
-                      "err = %d\n", n);
+                printk(UM_KERN_ERR "map_stub_pages : /proc/mm map for code "
+                       "failed, err = %d\n", n);
+                return -n;
         }
 
         if (stack) {
@@ -510,10 +586,15 @@ void map_stub_pages(int fd, unsigned long code,
                                       .offset  = map_offset
                 } } });
                 CATCH_EINTR(n = write(fd, &mmop, sizeof(mmop)));
-                if (n != sizeof(mmop))
-                        panic("map_stub_pages : /proc/mm map for data failed, "
-                              "err = %d\n", errno);
+                if (n != sizeof(mmop)) {
+                        n = errno;
+                        printk(UM_KERN_ERR "map_stub_pages : /proc/mm map for "
+                               "data failed, err = %d\n", n);
+                        return -n;
+                }
         }
+
+        return 0;
 }
 
 void new_thread(void *stack, jmp_buf *buf, void (*handler)(void))
@@ -574,7 +655,9 @@ int start_idle_thread(void *stack, jmp_buf *switch_buf)
                 kmalloc_ok = 0;
                 return 1;
         default:
-                panic("Bad sigsetjmp return in start_idle_thread - %d\n", n);
+                printk(UM_KERN_ERR "Bad sigsetjmp return in "
+                       "start_idle_thread - %d\n", n);
+                fatal_sigsegv();
         }
         longjmp(*switch_buf, 1);
 }
@@ -617,9 +700,11 @@ void __switch_mm(struct mm_id *mm_idp)
         if (proc_mm) {
                 err = ptrace(PTRACE_SWITCH_MM, userspace_pid[0], 0,
                              mm_idp->u.mm_fd);
-                if (err)
-                        panic("__switch_mm - PTRACE_SWITCH_MM failed, "
-                              "errno = %d\n", errno);
+                if (err) {
+                        printk(UM_KERN_ERR "__switch_mm - PTRACE_SWITCH_MM "
+                               "failed, errno = %d\n", errno);
+                        fatal_sigsegv();
+                }
         }
         else userspace_pid[0] = mm_idp->u.pid;
 }
diff --git a/arch/um/os-Linux/start_up.c b/arch/um/os-Linux/start_up.c
index b07887c36bb0..6d56d15884fd 100644
--- a/arch/um/os-Linux/start_up.c
+++ b/arch/um/os-Linux/start_up.c
@@ -411,7 +411,9 @@ static inline void check_skas3_ptrace_faultinfo(void)
                         non_fatal("found\n");
         }
 
-        init_registers(pid);
+        if (init_registers(pid))
+                fatal("Failed to initialize default registers");
+
         stop_ptraced_child(pid, 1, 1);
 }