Merge tag 'for-linus-4.8-rc0-tag' of git://git.kernel.org/pub/scm/linux/kernel/git...

[sfrench/cifs-2.6.git] / arch / x86 / kernel / signal_compat.c

diff --git a/arch/x86/kernel/signal_compat.c b/arch/x86/kernel/signal_compat.c
index dc3c0b1c816fabb7112426754c3e4bbc86df986a..b44564bf86a836f66808af13947cea34bd1a9717 100644 (file)
--- a/arch/x86/kernel/signal_compat.c
+++ b/arch/x86/kernel/signal_compat.c
@@ -1,11 +1,104 @@
 #include <linux/compat.h>
 #include <linux/uaccess.h>
 
+/*
+ * The compat_siginfo_t structure and handing code is very easy
+ * to break in several ways.  It must always be updated when new
+ * updates are made to the main siginfo_t, and
+ * copy_siginfo_to_user32() must be updated when the
+ * (arch-independent) copy_siginfo_to_user() is updated.
+ *
+ * It is also easy to put a new member in the compat_siginfo_t
+ * which has implicit alignment which can move internal structure
+ * alignment around breaking the ABI.  This can happen if you,
+ * for instance, put a plain 64-bit value in there.
+ */
+static inline void signal_compat_build_tests(void)
+{
+       int _sifields_offset = offsetof(compat_siginfo_t, _sifields);
+
+       /*
+        * If adding a new si_code, there is probably new data in
+        * the siginfo.  Make sure folks bumping the si_code
+        * limits also have to look at this code.  Make sure any
+        * new fields are handled in copy_siginfo_to_user32()!
+        */
+       BUILD_BUG_ON(NSIGILL  != 8);
+       BUILD_BUG_ON(NSIGFPE  != 8);
+       BUILD_BUG_ON(NSIGSEGV != 4);
+       BUILD_BUG_ON(NSIGBUS  != 5);
+       BUILD_BUG_ON(NSIGTRAP != 4);
+       BUILD_BUG_ON(NSIGCHLD != 6);
+       BUILD_BUG_ON(NSIGSYS  != 1);
+
+       /* This is part of the ABI and can never change in size: */
+       BUILD_BUG_ON(sizeof(compat_siginfo_t) != 128);
+       /*
+        * The offsets of all the (unioned) si_fields are fixed
+        * in the ABI, of course.  Make sure none of them ever
+        * move and are always at the beginning:
+        */
+       BUILD_BUG_ON(offsetof(compat_siginfo_t, _sifields) != 3 * sizeof(int));
+#define CHECK_CSI_OFFSET(name)   BUILD_BUG_ON(_sifields_offset != offsetof(compat_siginfo_t, _sifields.name))
+
+        /*
+        * Ensure that the size of each si_field never changes.
+        * If it does, it is a sign that the
+        * copy_siginfo_to_user32() code below needs to updated
+        * along with the size in the CHECK_SI_SIZE().
+        *
+        * We repeat this check for both the generic and compat
+        * siginfos.
+        *
+        * Note: it is OK for these to grow as long as the whole
+        * structure stays within the padding size (checked
+        * above).
+        */
+#define CHECK_CSI_SIZE(name, size) BUILD_BUG_ON(size != sizeof(((compat_siginfo_t *)0)->_sifields.name))
+#define CHECK_SI_SIZE(name, size) BUILD_BUG_ON(size != sizeof(((siginfo_t *)0)->_sifields.name))
+
+       CHECK_CSI_OFFSET(_kill);
+       CHECK_CSI_SIZE  (_kill, 2*sizeof(int));
+       CHECK_SI_SIZE   (_kill, 2*sizeof(int));
+
+       CHECK_CSI_OFFSET(_timer);
+       CHECK_CSI_SIZE  (_timer, 5*sizeof(int));
+       CHECK_SI_SIZE   (_timer, 6*sizeof(int));
+
+       CHECK_CSI_OFFSET(_rt);
+       CHECK_CSI_SIZE  (_rt, 3*sizeof(int));
+       CHECK_SI_SIZE   (_rt, 4*sizeof(int));
+
+       CHECK_CSI_OFFSET(_sigchld);
+       CHECK_CSI_SIZE  (_sigchld, 5*sizeof(int));
+       CHECK_SI_SIZE   (_sigchld, 8*sizeof(int));
+
+       CHECK_CSI_OFFSET(_sigchld_x32);
+       CHECK_CSI_SIZE  (_sigchld_x32, 7*sizeof(int));
+       /* no _sigchld_x32 in the generic siginfo_t */
+
+       CHECK_CSI_OFFSET(_sigfault);
+       CHECK_CSI_SIZE  (_sigfault, 4*sizeof(int));
+       CHECK_SI_SIZE   (_sigfault, 8*sizeof(int));
+
+       CHECK_CSI_OFFSET(_sigpoll);
+       CHECK_CSI_SIZE  (_sigpoll, 2*sizeof(int));
+       CHECK_SI_SIZE   (_sigpoll, 4*sizeof(int));
+
+       CHECK_CSI_OFFSET(_sigsys);
+       CHECK_CSI_SIZE  (_sigsys, 3*sizeof(int));
+       CHECK_SI_SIZE   (_sigsys, 4*sizeof(int));
+
+       /* any new si_fields should be added here */
+}
+
 int copy_siginfo_to_user32(compat_siginfo_t __user *to, const siginfo_t *from)
 {
        int err = 0;
        bool ia32 = test_thread_flag(TIF_IA32);
 
+       signal_compat_build_tests();
+
        if (!access_ok(VERIFY_WRITE, to, sizeof(compat_siginfo_t)))
                return -EFAULT;
 
@@ -32,6 +125,21 @@ int copy_siginfo_to_user32(compat_siginfo_t __user *to, const siginfo_t *from)
                                          &to->_sifields._pad[0]);
                        switch (from->si_code >> 16) {
                        case __SI_FAULT >> 16:
+                               if (from->si_signo == SIGBUS &&
+                                   (from->si_code == BUS_MCEERR_AR ||
+                                    from->si_code == BUS_MCEERR_AO))
+                                       put_user_ex(from->si_addr_lsb, &to->si_addr_lsb);
+
+                               if (from->si_signo == SIGSEGV) {
+                                       if (from->si_code == SEGV_BNDERR) {
+                                               compat_uptr_t lower = (unsigned long)&to->si_lower;
+                                               compat_uptr_t upper = (unsigned long)&to->si_upper;
+                                               put_user_ex(lower, &to->si_lower);
+                                               put_user_ex(upper, &to->si_upper);
+                                       }
+                                       if (from->si_code == SEGV_PKUERR)
+                                               put_user_ex(from->si_pkey, &to->si_pkey);
+                               }
                                break;
                        case __SI_SYS >> 16:
                                put_user_ex(from->si_syscall, &to->si_syscall);