Merge tag 'x86-core-2023-02-20' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

torvalds · torvalds · commit 8a68bd3e9ff6 · 2023-02-20T18:40:45.000-08:00
Pull x86 core updates from Ingo Molnar:

 - Clean up the signal frame layout tests

 - Suppress KMSAN false positive reports in arch_within_stack_frames()

* tag 'x86-core-2023-02-20' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  x86: Suppress KMSAN reports in arch_within_stack_frames()
  x86/signal/compat: Move sigaction_compat_abi() to signal_64.c
  x86/signal: Move siginfo field tests
diff --git a/arch/x86/include/asm/thread_info.h b/arch/x86/include/asm/thread_info.h
@@ -163,7 +163,12 @@ struct thread_info {
  *	GOOD_FRAME	if within a frame
  *	BAD_STACK	if placed across a frame boundary (or outside stack)
  *	NOT_STACK	unable to determine (no frame pointers, etc)
+ *
+ * This function reads pointers from the stack and dereferences them. The
+ * pointers may not have their KMSAN shadow set up properly, which may result
+ * in false positive reports. Disable instrumentation to avoid those.
  */
+__no_kmsan_checks
 static inline int arch_within_stack_frames(const void * const stack,
 					   const void * const stackend,
 					   const void *obj, unsigned long len)
diff --git a/arch/x86/kernel/Makefile b/arch/x86/kernel/Makefile
@@ -45,7 +45,6 @@ obj-y			+= head$(BITS).o
 obj-y			+= ebda.o
 obj-y			+= platform-quirks.o
 obj-y			+= process_$(BITS).o signal.o signal_$(BITS).o
-obj-$(CONFIG_COMPAT)	+= signal_compat.o
 obj-y			+= traps.o idt.o irq.o irq_$(BITS).o dumpstack_$(BITS).o
 obj-y			+= time.o ioport.o dumpstack.o nmi.o
 obj-$(CONFIG_MODIFY_LDT_SYSCALL)	+= ldt.o
diff --git a/arch/x86/kernel/signal_32.c b/arch/x86/kernel/signal_32.c
@@ -54,12 +54,14 @@ static inline void reload_segments(struct sigcontext_32 *sc)
 }
 
 #define sigset32_t			compat_sigset_t
+#define siginfo32_t			compat_siginfo_t
 #define restore_altstack32		compat_restore_altstack
 #define unsafe_save_altstack32		unsafe_compat_save_altstack
 
 #else
 
 #define sigset32_t			sigset_t
+#define siginfo32_t			siginfo_t
 #define __NR_ia32_sigreturn		__NR_sigreturn
 #define __NR_ia32_rt_sigreturn		__NR_rt_sigreturn
 #define restore_altstack32		restore_altstack
@@ -377,3 +379,128 @@ int ia32_setup_rt_frame(struct ksignal *ksig, struct pt_regs *regs)
 	user_access_end();
 	return -EFAULT;
 }
+
+/*
+ * The 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 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.
+ */
+
+/*
+* 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()!
+*/
+static_assert(NSIGILL  == 11);
+static_assert(NSIGFPE  == 15);
+static_assert(NSIGSEGV == 9);
+static_assert(NSIGBUS  == 5);
+static_assert(NSIGTRAP == 6);
+static_assert(NSIGCHLD == 6);
+static_assert(NSIGSYS  == 2);
+
+/* This is part of the ABI and can never change in size: */
+static_assert(sizeof(siginfo32_t) == 128);
+
+/* This is a part of the ABI and can never change in alignment */
+static_assert(__alignof__(siginfo32_t) == 4);
+
+/*
+* 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:
+*/
+static_assert(offsetof(siginfo32_t, _sifields) == 3 * sizeof(int));
+
+static_assert(offsetof(siginfo32_t, si_signo) == 0);
+static_assert(offsetof(siginfo32_t, si_errno) == 4);
+static_assert(offsetof(siginfo32_t, si_code)  == 8);
+
+/*
+* 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_SI_OFFSET(name)						\
+	static_assert(offsetof(siginfo32_t, _sifields) ==		\
+		      offsetof(siginfo32_t, _sifields.name))
+
+#define CHECK_SI_SIZE(name, size)					\
+	static_assert(sizeof_field(siginfo32_t, _sifields.name) == size)
+
+CHECK_SI_OFFSET(_kill);
+CHECK_SI_SIZE  (_kill, 2*sizeof(int));
+static_assert(offsetof(siginfo32_t, si_pid) == 0xC);
+static_assert(offsetof(siginfo32_t, si_uid) == 0x10);
+
+CHECK_SI_OFFSET(_timer);
+#ifdef CONFIG_COMPAT
+/* compat_siginfo_t doesn't have si_sys_private */
+CHECK_SI_SIZE  (_timer, 3*sizeof(int));
+#else
+CHECK_SI_SIZE  (_timer, 4*sizeof(int));
+#endif
+static_assert(offsetof(siginfo32_t, si_tid)     == 0x0C);
+static_assert(offsetof(siginfo32_t, si_overrun) == 0x10);
+static_assert(offsetof(siginfo32_t, si_value)   == 0x14);
+
+CHECK_SI_OFFSET(_rt);
+CHECK_SI_SIZE  (_rt, 3*sizeof(int));
+static_assert(offsetof(siginfo32_t, si_pid)   == 0x0C);
+static_assert(offsetof(siginfo32_t, si_uid)   == 0x10);
+static_assert(offsetof(siginfo32_t, si_value) == 0x14);
+
+CHECK_SI_OFFSET(_sigchld);
+CHECK_SI_SIZE  (_sigchld, 5*sizeof(int));
+static_assert(offsetof(siginfo32_t, si_pid)    == 0x0C);
+static_assert(offsetof(siginfo32_t, si_uid)    == 0x10);
+static_assert(offsetof(siginfo32_t, si_status) == 0x14);
+static_assert(offsetof(siginfo32_t, si_utime)  == 0x18);
+static_assert(offsetof(siginfo32_t, si_stime)  == 0x1C);
+
+CHECK_SI_OFFSET(_sigfault);
+CHECK_SI_SIZE  (_sigfault, 4*sizeof(int));
+static_assert(offsetof(siginfo32_t, si_addr) == 0x0C);
+
+static_assert(offsetof(siginfo32_t, si_trapno) == 0x10);
+
+static_assert(offsetof(siginfo32_t, si_addr_lsb) == 0x10);
+
+static_assert(offsetof(siginfo32_t, si_lower) == 0x14);
+static_assert(offsetof(siginfo32_t, si_upper) == 0x18);
+
+static_assert(offsetof(siginfo32_t, si_pkey) == 0x14);
+
+static_assert(offsetof(siginfo32_t, si_perf_data) == 0x10);
+static_assert(offsetof(siginfo32_t, si_perf_type) == 0x14);
+static_assert(offsetof(siginfo32_t, si_perf_flags) == 0x18);
+
+CHECK_SI_OFFSET(_sigpoll);
+CHECK_SI_SIZE  (_sigpoll, 2*sizeof(int));
+static_assert(offsetof(siginfo32_t, si_band) == 0x0C);
+static_assert(offsetof(siginfo32_t, si_fd)   == 0x10);
+
+CHECK_SI_OFFSET(_sigsys);
+CHECK_SI_SIZE  (_sigsys, 3*sizeof(int));
+static_assert(offsetof(siginfo32_t, si_call_addr) == 0x0C);
+static_assert(offsetof(siginfo32_t, si_syscall)   == 0x10);
+static_assert(offsetof(siginfo32_t, si_arch)      == 0x14);
+
+/* any new si_fields should be added here */
diff --git a/arch/x86/kernel/signal_64.c b/arch/x86/kernel/signal_64.c
@@ -381,3 +381,130 @@ COMPAT_SYSCALL_DEFINE0(x32_rt_sigreturn)
 	return 0;
 }
 #endif /* CONFIG_X86_X32_ABI */
+
+#ifdef CONFIG_COMPAT
+void sigaction_compat_abi(struct k_sigaction *act, struct k_sigaction *oact)
+{
+	if (!act)
+		return;
+
+	if (in_ia32_syscall())
+		act->sa.sa_flags |= SA_IA32_ABI;
+	if (in_x32_syscall())
+		act->sa.sa_flags |= SA_X32_ABI;
+}
+#endif /* CONFIG_COMPAT */
+
+/*
+* 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()!
+*/
+static_assert(NSIGILL  == 11);
+static_assert(NSIGFPE  == 15);
+static_assert(NSIGSEGV == 9);
+static_assert(NSIGBUS  == 5);
+static_assert(NSIGTRAP == 6);
+static_assert(NSIGCHLD == 6);
+static_assert(NSIGSYS  == 2);
+
+/* This is part of the ABI and can never change in size: */
+static_assert(sizeof(siginfo_t) == 128);
+
+/* This is a part of the ABI and can never change in alignment */
+static_assert(__alignof__(siginfo_t) == 8);
+
+/*
+* 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:
+*/
+static_assert(offsetof(siginfo_t, si_signo) == 0);
+static_assert(offsetof(siginfo_t, si_errno) == 4);
+static_assert(offsetof(siginfo_t, si_code)  == 8);
+
+/*
+* 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_SI_OFFSET(name)						\
+	static_assert(offsetof(siginfo_t, _sifields) == 		\
+		      offsetof(siginfo_t, _sifields.name))
+#define CHECK_SI_SIZE(name, size)					\
+	static_assert(sizeof_field(siginfo_t, _sifields.name) == size)
+
+CHECK_SI_OFFSET(_kill);
+CHECK_SI_SIZE  (_kill, 2*sizeof(int));
+static_assert(offsetof(siginfo_t, si_pid) == 0x10);
+static_assert(offsetof(siginfo_t, si_uid) == 0x14);
+
+CHECK_SI_OFFSET(_timer);
+CHECK_SI_SIZE  (_timer, 6*sizeof(int));
+static_assert(offsetof(siginfo_t, si_tid)     == 0x10);
+static_assert(offsetof(siginfo_t, si_overrun) == 0x14);
+static_assert(offsetof(siginfo_t, si_value)   == 0x18);
+
+CHECK_SI_OFFSET(_rt);
+CHECK_SI_SIZE  (_rt, 4*sizeof(int));
+static_assert(offsetof(siginfo_t, si_pid)   == 0x10);
+static_assert(offsetof(siginfo_t, si_uid)   == 0x14);
+static_assert(offsetof(siginfo_t, si_value) == 0x18);
+
+CHECK_SI_OFFSET(_sigchld);
+CHECK_SI_SIZE  (_sigchld, 8*sizeof(int));
+static_assert(offsetof(siginfo_t, si_pid)    == 0x10);
+static_assert(offsetof(siginfo_t, si_uid)    == 0x14);
+static_assert(offsetof(siginfo_t, si_status) == 0x18);
+static_assert(offsetof(siginfo_t, si_utime)  == 0x20);
+static_assert(offsetof(siginfo_t, si_stime)  == 0x28);
+
+#ifdef CONFIG_X86_X32_ABI
+/* no _sigchld_x32 in the generic siginfo_t */
+static_assert(sizeof_field(compat_siginfo_t, _sifields._sigchld_x32) ==
+	      7*sizeof(int));
+static_assert(offsetof(compat_siginfo_t, _sifields) ==
+	      offsetof(compat_siginfo_t, _sifields._sigchld_x32));
+static_assert(offsetof(compat_siginfo_t, _sifields._sigchld_x32._utime)  == 0x18);
+static_assert(offsetof(compat_siginfo_t, _sifields._sigchld_x32._stime)  == 0x20);
+#endif
+
+CHECK_SI_OFFSET(_sigfault);
+CHECK_SI_SIZE  (_sigfault, 8*sizeof(int));
+static_assert(offsetof(siginfo_t, si_addr)	== 0x10);
+
+static_assert(offsetof(siginfo_t, si_trapno)	== 0x18);
+
+static_assert(offsetof(siginfo_t, si_addr_lsb)	== 0x18);
+
+static_assert(offsetof(siginfo_t, si_lower)	== 0x20);
+static_assert(offsetof(siginfo_t, si_upper)	== 0x28);
+
+static_assert(offsetof(siginfo_t, si_pkey)	== 0x20);
+
+static_assert(offsetof(siginfo_t, si_perf_data)	 == 0x18);
+static_assert(offsetof(siginfo_t, si_perf_type)	 == 0x20);
+static_assert(offsetof(siginfo_t, si_perf_flags) == 0x24);
+
+CHECK_SI_OFFSET(_sigpoll);
+CHECK_SI_SIZE  (_sigpoll, 4*sizeof(int));
+static_assert(offsetof(siginfo_t, si_band) == 0x10);
+static_assert(offsetof(siginfo_t, si_fd)   == 0x18);
+
+CHECK_SI_OFFSET(_sigsys);
+CHECK_SI_SIZE  (_sigsys, 4*sizeof(int));
+static_assert(offsetof(siginfo_t, si_call_addr) == 0x10);
+static_assert(offsetof(siginfo_t, si_syscall)   == 0x18);
+static_assert(offsetof(siginfo_t, si_arch)      == 0x1C);
+
+/* any new si_fields should be added here */
diff --git a/arch/x86/kernel/signal_compat.c b/arch/x86/kernel/signal_compat.c
