Merge branch 'for-5.2-vsprintf-hardening' into for-linus

Documentation/core-api/printk-formats.rst

@@ -58,6 +58,14 @@ A raw pointer value may be printed with %p which will hash the address
 before printing. The kernel also supports extended specifiers for printing
 pointers of different types.
 
+Some of the extended specifiers print the data on the given address instead
+of printing the address itself. In this case, the following error messages
+might be printed instead of the unreachable information::
+
+	(null)	 data on plain NULL address
+	(efault) data on invalid address
+	(einval) invalid data on a valid address
+
 Plain Pointers
 --------------
 

lib/test_printf.c

@@ -239,6 +239,7 @@ plain_format(void)
 #define PTR ((void *)0x456789ab)
 #define PTR_STR "456789ab"
 #define PTR_VAL_NO_CRNG "(ptrval)"
+#define ZEROS ""
 
 static int __init
 plain_format(void)
@@ -268,7 +269,6 @@ plain_hash_to_buffer(const void *p, char *buf, size_t len)
 	return 0;
 }
 
-
 static int __init
 plain_hash(void)
 {
@@ -325,6 +325,24 @@ test_hashed(const char *fmt, const void *p)
 	test(buf, fmt, p);
 }
 
+static void __init
+null_pointer(void)
+{
+	test_hashed("%p", NULL);
+	test(ZEROS "00000000", "%px", NULL);
+	test("(null)", "%pE", NULL);
+}
+
+#define PTR_INVALID ((void *)0x000000ab)
+
+static void __init
+invalid_pointer(void)
+{
+	test_hashed("%p", PTR_INVALID);
+	test(ZEROS "000000ab", "%px", PTR_INVALID);
+	test("(efault)", "%pE", PTR_INVALID);
+}
+
 static void __init
 symbol_ptr(void)
 {
@@ -462,8 +480,7 @@ struct_rtc_time(void)
 		.tm_year = 118,
 	};
 
-	test_hashed("%pt", &tm);
-
+	test("(%ptR?)", "%pt", &tm);
 	test("2018-11-26T05:35:43", "%ptR", &tm);
 	test("0118-10-26T05:35:43", "%ptRr", &tm);
 	test("05:35:43|2018-11-26", "%ptRt|%ptRd", &tm, &tm);
@@ -572,6 +589,8 @@ static void __init
 test_pointer(void)
 {
 	plain();
+	null_pointer();
+	invalid_pointer();
 	symbol_ptr();
 	kernel_ptr();
 	struct_resource();

lib/vsprintf.c

@@ -593,15 +593,13 @@ char *widen_string(char *buf, int n, char *end, struct printf_spec spec)
 	return buf;
 }
 
-static noinline_for_stack
-char *string(char *buf, char *end, const char *s, struct printf_spec spec)
+/* Handle string from a well known address. */
+static char *string_nocheck(char *buf, char *end, const char *s,
+			    struct printf_spec spec)
 {
 	int len = 0;
 	size_t lim = spec.precision;
 
-	if ((unsigned long)s < PAGE_SIZE)
-		s = "(null)";
-
 	while (lim--) {
 		char c = *s++;
 		if (!c)
@@ -614,9 +612,67 @@ char *string(char *buf, char *end, const char *s, struct printf_spec spec)
 	return widen_string(buf, len, end, spec);
 }
 
+/* Be careful: error messages must fit into the given buffer. */
+static char *error_string(char *buf, char *end, const char *s,
+			  struct printf_spec spec)
+{
+	/*
+	 * Hard limit to avoid a completely insane messages. It actually
+	 * works pretty well because most error messages are in
+	 * the many pointer format modifiers.
+	 */
+	if (spec.precision == -1)
+		spec.precision = 2 * sizeof(void *);
+
+	return string_nocheck(buf, end, s, spec);
+}
+
+/*
+ * This is not a fool-proof test. 99% of the time that this will fault is
+ * due to a bad pointer, not one that crosses into bad memory. Just test
+ * the address to make sure it doesn't fault due to a poorly added printk
+ * during debugging.
+ */
+static const char *check_pointer_msg(const void *ptr)
+{
+	char byte;
+
+	if (!ptr)
+		return "(null)";
+
+	if (probe_kernel_address(ptr, byte))
+		return "(efault)";
+
+	return NULL;
+}
+
+static int check_pointer(char **buf, char *end, const void *ptr,
+			 struct printf_spec spec)
+{
+	const char *err_msg;
+
+	err_msg = check_pointer_msg(ptr);
+	if (err_msg) {
+		*buf = error_string(*buf, end, err_msg, spec);
+		return -EFAULT;
+	}
+
+	return 0;
+}
+
 static noinline_for_stack
-char *pointer_string(char *buf, char *end, const void *ptr,
-		     struct printf_spec spec)
+char *string(char *buf, char *end, const char *s,
+	     struct printf_spec spec)
+{
+	if (check_pointer(&buf, end, s, spec))
+		return buf;
+
+	return string_nocheck(buf, end, s, spec);
+}
+
+static char *pointer_string(char *buf, char *end,
+			    const void *ptr,
+			    struct printf_spec spec)
 {
 	spec.base = 16;
 	spec.flags |= SMALL;
@@ -701,7 +757,7 @@ static char *ptr_to_id(char *buf, char *end, const void *ptr,
 	if (static_branch_unlikely(&not_filled_random_ptr_key)) {
 		spec.field_width = 2 * sizeof(ptr);
 		/* string length must be less than default_width */
-		return string(buf, end, str, spec);
+		return error_string(buf, end, str, spec);
 	}
 
 #ifdef CONFIG_64BIT
@@ -717,6 +773,55 @@ static char *ptr_to_id(char *buf, char *end, const void *ptr,
 	return pointer_string(buf, end, (const void *)hashval, spec);
 }
 
+int kptr_restrict __read_mostly;
+
+static noinline_for_stack
+char *restricted_pointer(char *buf, char *end, const void *ptr,
+			 struct printf_spec spec)
+{
+	switch (kptr_restrict) {
+	case 0:
+		/* Handle as %p, hash and do _not_ leak addresses. */
+		return ptr_to_id(buf, end, ptr, spec);
+	case 1: {
+		const struct cred *cred;
+
+		/*
+		 * kptr_restrict==1 cannot be used in IRQ context
+		 * because its test for CAP_SYSLOG would be meaningless.
+		 */
+		if (in_irq() || in_serving_softirq() || in_nmi()) {
+			if (spec.field_width == -1)
+				spec.field_width = 2 * sizeof(ptr);
+			return error_string(buf, end, "pK-error", spec);
+		}
+
+		/*
+		 * Only print the real pointer value if the current
+		 * process has CAP_SYSLOG and is running with the
+		 * same credentials it started with. This is because
+		 * access to files is checked at open() time, but %pK
+		 * checks permission at read() time. We don't want to
+		 * leak pointer values if a binary opens a file using
+		 * %pK and then elevates privileges before reading it.
+		 */
+		cred = current_cred();
+		if (!has_capability_noaudit(current, CAP_SYSLOG) ||
+		    !uid_eq(cred->euid, cred->uid) ||
+		    !gid_eq(cred->egid, cred->gid))
+			ptr = NULL;
+		break;
+	}
+	case 2:
+	default:
+		/* Always print 0's for %pK */
+		ptr = NULL;
+		break;
+	}
+
+	return pointer_string(buf, end, ptr, spec);
+}
+
 static noinline_for_stack
 char *dentry_name(char *buf, char *end, const struct dentry *d, struct printf_spec spec,
 		  const char *fmt)
@@ -736,6 +841,11 @@ char *dentry_name(char *buf, char *end, const struct dentry *d, struct printf_sp
 
 	rcu_read_lock();
 	for (i = 0; i < depth; i++, d = p) {
+		if (check_pointer(&buf, end, d, spec)) {
+			rcu_read_unlock();
+			return buf;
+		}
+
 		p = READ_ONCE(d->d_parent);
 		array[i] = READ_ONCE(d->d_name.name);
 		if (p == d) {
@@ -766,8 +876,12 @@ static noinline_for_stack
 char *bdev_name(char *buf, char *end, struct block_device *bdev,
 		struct printf_spec spec, const char *fmt)
 {
-	struct gendisk *hd = bdev->bd_disk;
-	
+	struct gendisk *hd;
+
+	if (check_pointer(&buf, end, bdev, spec))
+		return buf;
+
+	hd = bdev->bd_disk;
 	buf = string(buf, end, hd->disk_name, spec);
 	if (bdev->bd_part->partno) {
 		if (isdigit(hd->disk_name[strlen(hd->disk_name)-1])) {
@@ -802,7 +916,7 @@ char *symbol_string(char *buf, char *end, void *ptr,
 	else
 		sprint_symbol_no_offset(sym, value);
 
-	return string(buf, end, sym, spec);
+	return string_nocheck(buf, end, sym, spec);
 #else
 	return special_hex_number(buf, end, value, sizeof(void *));
 #endif
@@ -886,29 +1000,32 @@ char *resource_string(char *buf, char *end, struct resource *res,
 	int decode = (fmt[0] == 'R') ? 1 : 0;
 	const struct printf_spec *specp;
 
+	if (check_pointer(&buf, end, res, spec))
+		return buf;
+
 	*p++ = '[';
 	if (res->flags & IORESOURCE_IO) {
-		p = string(p, pend, "io  ", str_spec);
+		p = string_nocheck(p, pend, "io  ", str_spec);
 		specp = &io_spec;
 	} else if (res->flags & IORESOURCE_MEM) {
-		p = string(p, pend, "mem ", str_spec);
+		p = string_nocheck(p, pend, "mem ", str_spec);
 		specp = &mem_spec;
 	} else if (res->flags & IORESOURCE_IRQ) {
-		p = string(p, pend, "irq ", str_spec);
+		p = string_nocheck(p, pend, "irq ", str_spec);
 		specp = &default_dec_spec;
 	} else if (res->flags & IORESOURCE_DMA) {
-		p = string(p, pend, "dma ", str_spec);
+		p = string_nocheck(p, pend, "dma ", str_spec);
 		specp = &default_dec_spec;
 	} else if (res->flags & IORESOURCE_BUS) {
-		p = string(p, pend, "bus ", str_spec);
+		p = string_nocheck(p, pend, "bus ", str_spec);
 		specp = &bus_spec;
 	} else {
-		p = string(p, pend, "??? ", str_spec);
+		p = string_nocheck(p, pend, "??? ", str_spec);
 		specp = &mem_spec;
 		decode = 0;
 	}
 	if (decode && res->flags & IORESOURCE_UNSET) {
-		p = string(p, pend, "size ", str_spec);
+		p = string_nocheck(p, pend, "size ", str_spec);
 		p = number(p, pend, resource_size(res), *specp);
 	} else {
 		p = number(p, pend, res->start, *specp);
@@ -919,21 +1036,21 @@ char *resource_string(char *buf, char *end, struct resource *res,
 	}
 	if (decode) {
 		if (res->flags & IORESOURCE_MEM_64)
-			p = string(p, pend, " 64bit", str_spec);
+			p = string_nocheck(p, pend, " 64bit", str_spec);
 		if (res->flags & IORESOURCE_PREFETCH)
-			p = string(p, pend, " pref", str_spec);
+			p = string_nocheck(p, pend, " pref", str_spec);
 		if (res->flags & IORESOURCE_WINDOW)
-			p = string(p, pend, " window", str_spec);
+			p = string_nocheck(p, pend, " window", str_spec);
 		if (res->flags & IORESOURCE_DISABLED)
-			p = string(p, pend, " disabled", str_spec);
+			p = string_nocheck(p, pend, " disabled", str_spec);
 	} else {
-		p = string(p, pend, " flags ", str_spec);
+		p = string_nocheck(p, pend, " flags ", str_spec);
 		p = number(p, pend, res->flags, default_flag_spec);
 	}
 	*p++ = ']';
 	*p = '\0';
 
-	return string(buf, end, sym, spec);
+	return string_nocheck(buf, end, sym, spec);
 }
 
 static noinline_for_stack
@@ -948,9 +1065,8 @@ char *hex_string(char *buf, char *end, u8 *addr, struct printf_spec spec,
 		/* nothing to print */
 		return buf;
 
-	if (ZERO_OR_NULL_PTR(addr))
-		/* NULL pointer */
-		return string(buf, end, NULL, spec);
+	if (check_pointer(&buf, end, addr, spec))
+		return buf;
 
 	switch (fmt[1]) {
 	case 'C':
@@ -997,6 +1113,9 @@ char *bitmap_string(char *buf, char *end, unsigned long *bitmap,
 	int i, chunksz;
 	bool first = true;
 
+	if (check_pointer(&buf, end, bitmap, spec))
+		return buf;
+
 	/* reused to print numbers */
 	spec = (struct printf_spec){ .flags = SMALL | ZEROPAD, .base = 16 };
 
@@ -1038,6 +1157,9 @@ char *bitmap_list_string(char *buf, char *end, unsigned long *bitmap,
 	int cur, rbot, rtop;
 	bool first = true;
 
+	if (check_pointer(&buf, end, bitmap, spec))
+		return buf;
+
 	rbot = cur = find_first_bit(bitmap, nr_bits);
 	while (cur < nr_bits) {
 		rtop = cur;
@@ -1076,6 +1198,9 @@ char *mac_address_string(char *buf, char *end, u8 *addr,
 	char separator;
 	bool reversed = false;
 
+	if (check_pointer(&buf, end, addr, spec))
+		return buf;
+
 	switch (fmt[1]) {
 	case 'F':
 		separator = '-';
@@ -1101,7 +1226,7 @@ char *mac_address_string(char *buf, char *end, u8 *addr,
 	}
 	*p = '\0';
 
-	return string(buf, end, mac_addr, spec);
+	return string_nocheck(buf, end, mac_addr, spec);
 }
 
 static noinline_for_stack
@@ -1264,7 +1389,7 @@ char *ip6_addr_string(char *buf, char *end, const u8 *addr,
 	else
 		ip6_string(ip6_addr, addr, fmt);
 
-	return string(buf, end, ip6_addr, spec);
+	return string_nocheck(buf, end, ip6_addr, spec);
 }
 
 static noinline_for_stack
@@ -1275,7 +1400,7 @@ char *ip4_addr_string(char *buf, char *end, const u8 *addr,
 
 	ip4_string(ip4_addr, addr, fmt);
 
-	return string(buf, end, ip4_addr, spec);
+	return string_nocheck(buf, end, ip4_addr, spec);
 }
 
 static noinline_for_stack
@@ -1337,7 +1462,7 @@ char *ip6_addr_string_sa(char *buf, char *end, const struct sockaddr_in6 *sa,
 	}
 	*p = '\0';
 
-	return string(buf, end, ip6_addr, spec);
+	return string_nocheck(buf, end, ip6_addr, spec);
 }
 
 static noinline_for_stack
@@ -1372,7 +1497,42 @@ char *ip4_addr_string_sa(char *buf, char *end, const struct sockaddr_in *sa,
 	}
 	*p = '\0';
 
-	return string(buf, end, ip4_addr, spec);
+	return string_nocheck(buf, end, ip4_addr, spec);
+}
+
+static noinline_for_stack
+char *ip_addr_string(char *buf, char *end, const void *ptr,
+		     struct printf_spec spec, const char *fmt)
+{
+	char *err_fmt_msg;
+
+	if (check_pointer(&buf, end, ptr, spec))
+		return buf;
+
+	switch (fmt[1]) {
+	case '6':
+		return ip6_addr_string(buf, end, ptr, spec, fmt);
+	case '4':
+		return ip4_addr_string(buf, end, ptr, spec, fmt);
+	case 'S': {
+		const union {
+			struct sockaddr		raw;
+			struct sockaddr_in	v4;
+			struct sockaddr_in6	v6;
+		} *sa = ptr;
+
+		switch (sa->raw.sa_family) {
+		case AF_INET:
+			return ip4_addr_string_sa(buf, end, &sa->v4, spec, fmt);
+		case AF_INET6:
+			return ip6_addr_string_sa(buf, end, &sa->v6, spec, fmt);
+		default:
+			return error_string(buf, end, "(einval)", spec);
+		}}
+	}
+
+	err_fmt_msg = fmt[0] == 'i' ? "(%pi?)" : "(%pI?)";
+	return error_string(buf, end, err_fmt_msg, spec);
 }
 
 static noinline_for_stack
@@ -1387,9 +1547,8 @@ char *escaped_string(char *buf, char *end, u8 *addr, struct printf_spec spec,
 	if (spec.field_width == 0)
 		return buf;				/* nothing to print */
 
-	if (ZERO_OR_NULL_PTR(addr))
-		return string(buf, end, NULL, spec);	/* NULL pointer */
-
+	if (check_pointer(&buf, end, addr, spec))
+		return buf;
 
 	do {
 		switch (fmt[count++]) {
@@ -1435,6 +1594,21 @@ char *escaped_string(char *buf, char *end, u8 *addr, struct printf_spec spec,
 	return buf;
 }
 
+static char *va_format(char *buf, char *end, struct va_format *va_fmt,
+		       struct printf_spec spec, const char *fmt)
+{
+	va_list va;
+
+	if (check_pointer(&buf, end, va_fmt, spec))
+		return buf;
+
+	va_copy(va, *va_fmt->va);
+	buf += vsnprintf(buf, end > buf ? end - buf : 0, va_fmt->fmt, va);
+	va_end(va);
+
+	return buf;
+}
+
 static noinline_for_stack
 char *uuid_string(char *buf, char *end, const u8 *addr,
 		  struct printf_spec spec, const char *fmt)
@@ -1445,6 +1619,9 @@ char *uuid_string(char *buf, char *end, const u8 *addr,
 	const u8 *index = uuid_index;
 	bool uc = false;
 
+	if (check_pointer(&buf, end, addr, spec))
+		return buf;
+
 	switch (*(++fmt)) {
 	case 'L':
 		uc = true;		/* fall-through */
@@ -1473,56 +1650,7 @@ char *uuid_string(char *buf, char *end, const u8 *addr,
 
 	*p = 0;
 
-	return string(buf, end, uuid, spec);
-}
-
-int kptr_restrict __read_mostly;
-
-static noinline_for_stack
-char *restricted_pointer(char *buf, char *end, const void *ptr,
-			 struct printf_spec spec)
-{
-	switch (kptr_restrict) {
-	case 0:
-		/* Always print %pK values */
-		break;
-	case 1: {
-		const struct cred *cred;
-
-		/*
-		 * kptr_restrict==1 cannot be used in IRQ context
-		 * because its test for CAP_SYSLOG would be meaningless.
-		 */
-		if (in_irq() || in_serving_softirq() || in_nmi()) {
-			if (spec.field_width == -1)
-				spec.field_width = 2 * sizeof(ptr);
-			return string(buf, end, "pK-error", spec);
-		}
-
-		/*
-		 * Only print the real pointer value if the current
-		 * process has CAP_SYSLOG and is running with the
-		 * same credentials it started with. This is because
-		 * access to files is checked at open() time, but %pK
-		 * checks permission at read() time. We don't want to
-		 * leak pointer values if a binary opens a file using
-		 * %pK and then elevates privileges before reading it.
-		 */
-		cred = current_cred();
-		if (!has_capability_noaudit(current, CAP_SYSLOG) ||
-		    !uid_eq(cred->euid, cred->uid) ||
-		    !gid_eq(cred->egid, cred->gid))
-			ptr = NULL;
-		break;
-	}
-	case 2:
-	default:
-		/* Always print 0's for %pK */
-		ptr = NULL;
-		break;
-	}
-
-	return pointer_string(buf, end, ptr, spec);
+	return string_nocheck(buf, end, uuid, spec);
 }
 
 static noinline_for_stack
@@ -1532,24 +1660,31 @@ char *netdev_bits(char *buf, char *end, const void *addr,
 	unsigned long long num;
 	int size;
 
+	if (check_pointer(&buf, end, addr, spec))
+		return buf;
+
 	switch (fmt[1]) {
 	case 'F':
 		num = *(const netdev_features_t *)addr;
 		size = sizeof(netdev_features_t);
 		break;
 	default:
-		return ptr_to_id(buf, end, addr, spec);
+		return error_string(buf, end, "(%pN?)", spec);
 	}
 
 	return special_hex_number(buf, end, num, size);
 }
 
 static noinline_for_stack
-char *address_val(char *buf, char *end, const void *addr, const char *fmt)
+char *address_val(char *buf, char *end, const void *addr,
+		  struct printf_spec spec, const char *fmt)
 {
 	unsigned long long num;
 	int size;
 
+	if (check_pointer(&buf, end, addr, spec))
+		return buf;
+
 	switch (fmt[1]) {
 	case 'd':
 		num = *(const dma_addr_t *)addr;
@@ -1601,12 +1736,16 @@ char *time_str(char *buf, char *end, const struct rtc_time *tm, bool r)
 }
 
 static noinline_for_stack
-char *rtc_str(char *buf, char *end, const struct rtc_time *tm, const char *fmt)
+char *rtc_str(char *buf, char *end, const struct rtc_time *tm,
+	      struct printf_spec spec, const char *fmt)
 {
 	bool have_t = true, have_d = true;
 	bool raw = false;
 	int count = 2;
 
+	if (check_pointer(&buf, end, tm, spec))
+		return buf;
+
 	switch (fmt[count]) {
 	case 'd':
 		have_t = false;
@@ -1640,9 +1779,9 @@ char *time_and_date(char *buf, char *end, void *ptr, struct printf_spec spec,
 {
 	switch (fmt[1]) {
 	case 'R':
-		return rtc_str(buf, end, (const struct rtc_time *)ptr, fmt);
+		return rtc_str(buf, end, (const struct rtc_time *)ptr, spec, fmt);
 	default:
-		return ptr_to_id(buf, end, ptr, spec);
+		return error_string(buf, end, "(%ptR?)", spec);
 	}
 }
 
@@ -1650,8 +1789,11 @@ static noinline_for_stack
 char *clock(char *buf, char *end, struct clk *clk, struct printf_spec spec,
 	    const char *fmt)
 {
-	if (!IS_ENABLED(CONFIG_HAVE_CLK) || !clk)
-		return string(buf, end, NULL, spec);
+	if (!IS_ENABLED(CONFIG_HAVE_CLK))
+		return error_string(buf, end, "(%pC?)", spec);
+
+	if (check_pointer(&buf, end, clk, spec))
+		return buf;
 
 	switch (fmt[1]) {
 	case 'n':
@@ -1659,7 +1801,7 @@ char *clock(char *buf, char *end, struct clk *clk, struct printf_spec spec,
 #ifdef CONFIG_COMMON_CLK
 		return string(buf, end, __clk_get_name(clk), spec);
 #else
-		return ptr_to_id(buf, end, clk, spec);
+		return error_string(buf, end, "(%pC?)", spec);
 #endif
 	}
 }
@@ -1692,11 +1834,15 @@ char *format_flags(char *buf, char *end, unsigned long flags,
 }
 
 static noinline_for_stack
-char *flags_string(char *buf, char *end, void *flags_ptr, const char *fmt)
+char *flags_string(char *buf, char *end, void *flags_ptr,
+		   struct printf_spec spec, const char *fmt)
 {
 	unsigned long flags;
 	const struct trace_print_flags *names;
 
+	if (check_pointer(&buf, end, flags_ptr, spec))
+		return buf;
+
 	switch (fmt[1]) {
 	case 'p':
 		flags = *(unsigned long *)flags_ptr;
@@ -1713,8 +1859,7 @@ char *flags_string(char *buf, char *end, void *flags_ptr, const char *fmt)
 		names = gfpflag_names;
 		break;
 	default:
-		WARN_ONCE(1, "Unsupported flags modifier: %c\n", fmt[1]);
-		return buf;
+		return error_string(buf, end, "(%pG?)", spec);
 	}
 
 	return format_flags(buf, end, flags, names);
@@ -1736,13 +1881,13 @@ char *device_node_gen_full_name(const struct device_node *np, char *buf, char *e
 
 	/* special case for root node */
 	if (!parent)
-		return string(buf, end, "/", default_str_spec);
+		return string_nocheck(buf, end, "/", default_str_spec);
 
 	for (depth = 0; parent->parent; depth++)
 		parent = parent->parent;
 
 	for ( ; depth >= 0; depth--) {
-		buf = string(buf, end, "/", default_str_spec);
+		buf = string_nocheck(buf, end, "/", default_str_spec);
 		buf = string(buf, end, device_node_name_for_depth(np, depth),
 			     default_str_spec);
 	}
@@ -1770,10 +1915,10 @@ char *device_node_string(char *buf, char *end, struct device_node *dn,
 	str_spec.field_width = -1;
 
 	if (!IS_ENABLED(CONFIG_OF))
-		return string(buf, end, "(!OF)", spec);
+		return error_string(buf, end, "(%pOF?)", spec);
 
-	if ((unsigned long)dn < PAGE_SIZE)
-		return string(buf, end, "(null)", spec);
+	if (check_pointer(&buf, end, dn, spec))
+		return buf;
 
 	/* simple case without anything any more format specifiers */
 	fmt++;
@@ -1814,7 +1959,7 @@ char *device_node_string(char *buf, char *end, struct device_node *dn,
 			tbuf[2] = of_node_check_flag(dn, OF_POPULATED) ? 'P' : '-';
 			tbuf[3] = of_node_check_flag(dn, OF_POPULATED_BUS) ? 'B' : '-';
 			tbuf[4] = 0;
-			buf = string(buf, end, tbuf, str_spec);
+			buf = string_nocheck(buf, end, tbuf, str_spec);
 			break;
 		case 'c':	/* major compatible string */
 			ret = of_property_read_string(dn, "compatible", &p);
@@ -1825,10 +1970,10 @@ char *device_node_string(char *buf, char *end, struct device_node *dn,
 			has_mult = false;
 			of_property_for_each_string(dn, "compatible", prop, p) {
 				if (has_mult)
-					buf = string(buf, end, ",", str_spec);
-				buf = string(buf, end, "\"", str_spec);
+					buf = string_nocheck(buf, end, ",", str_spec);
+				buf = string_nocheck(buf, end, "\"", str_spec);
 				buf = string(buf, end, p, str_spec);
-				buf = string(buf, end, "\"", str_spec);
+				buf = string_nocheck(buf, end, "\"", str_spec);
 
 				has_mult = true;
 			}
@@ -1841,6 +1986,17 @@ char *device_node_string(char *buf, char *end, struct device_node *dn,
 	return widen_string(buf, buf - buf_start, end, spec);
 }
 
+static char *kobject_string(char *buf, char *end, void *ptr,
+			    struct printf_spec spec, const char *fmt)
+{
+	switch (fmt[1]) {
+	case 'F':
+		return device_node_string(buf, end, ptr, spec, fmt + 1);
+	}
+
+	return error_string(buf, end, "(%pO?)", spec);
+}
+
 /*
  * Show a '%p' thing.  A kernel extension is that the '%p' is followed
  * by an extra set of alphanumeric characters that are extended format
@@ -1957,18 +2113,6 @@ static noinline_for_stack
 char *pointer(const char *fmt, char *buf, char *end, void *ptr,
 	      struct printf_spec spec)
 {
-	const int default_width = 2 * sizeof(void *);
-
-	if (!ptr && *fmt != 'K' && *fmt != 'x') {
-		/*
-		 * Print (null) with the same width as a pointer so it makes
-		 * tabular output look nice.
-		 */
-		if (spec.field_width == -1)
-			spec.field_width = default_width;
-		return string(buf, end, "(null)", spec);
-	}
-
 	switch (*fmt) {
 	case 'F':
 	case 'f':
@@ -2004,50 +2148,19 @@ char *pointer(const char *fmt, char *buf, char *end, void *ptr,
 					 * 4:	001.002.003.004
 					 * 6:   000102...0f
 					 */
-		switch (fmt[1]) {
-		case '6':
-			return ip6_addr_string(buf, end, ptr, spec, fmt);
-		case '4':
-			return ip4_addr_string(buf, end, ptr, spec, fmt);
-		case 'S': {
-			const union {
-				struct sockaddr		raw;
-				struct sockaddr_in	v4;
-				struct sockaddr_in6	v6;
-			} *sa = ptr;
-
-			switch (sa->raw.sa_family) {
-			case AF_INET:
-				return ip4_addr_string_sa(buf, end, &sa->v4, spec, fmt);
-			case AF_INET6:
-				return ip6_addr_string_sa(buf, end, &sa->v6, spec, fmt);
-			default:
-				return string(buf, end, "(invalid address)", spec);
-			}}
-		}
-		break;
+		return ip_addr_string(buf, end, ptr, spec, fmt);
 	case 'E':
 		return escaped_string(buf, end, ptr, spec, fmt);
 	case 'U':
 		return uuid_string(buf, end, ptr, spec, fmt);
 	case 'V':
-		{
-			va_list va;
-
-			va_copy(va, *((struct va_format *)ptr)->va);
-			buf += vsnprintf(buf, end > buf ? end - buf : 0,
-					 ((struct va_format *)ptr)->fmt, va);
-			va_end(va);
-			return buf;
-		}
+		return va_format(buf, end, ptr, spec, fmt);
 	case 'K':
-		if (!kptr_restrict)
-			break;
 		return restricted_pointer(buf, end, ptr, spec);
 	case 'N':
 		return netdev_bits(buf, end, ptr, spec, fmt);
 	case 'a':
-		return address_val(buf, end, ptr, fmt);
+		return address_val(buf, end, ptr, spec, fmt);
 	case 'd':
 		return dentry_name(buf, end, ptr, spec, fmt);
 	case 't':
@@ -2064,13 +2177,9 @@ char *pointer(const char *fmt, char *buf, char *end, void *ptr,
 #endif
 
 	case 'G':
-		return flags_string(buf, end, ptr, fmt);
+		return flags_string(buf, end, ptr, spec, fmt);
 	case 'O':
-		switch (fmt[1]) {
-		case 'F':
-			return device_node_string(buf, end, ptr, spec, fmt + 1);
-		}
-		break;
+		return kobject_string(buf, end, ptr, spec, fmt);
 	case 'x':
 		return pointer_string(buf, end, ptr, spec);
 	}
@@ -2685,11 +2794,13 @@ int vbin_printf(u32 *bin_buf, size_t size, const char *fmt, va_list args)
 
 		case FORMAT_TYPE_STR: {
 			const char *save_str = va_arg(args, char *);
+			const char *err_msg;
 			size_t len;
 
-			if ((unsigned long)save_str > (unsigned long)-PAGE_SIZE
-					|| (unsigned long)save_str < PAGE_SIZE)
-				save_str = "(null)";
+			err_msg = check_pointer_msg(save_str);
+			if (err_msg)
+				save_str = err_msg;
+
 			len = strlen(save_str) + 1;
 			if (str + len < end)
 				memcpy(str, save_str, len);