Commit d529ac41 authored by Petr Mladek's avatar Petr Mladek
Browse files

vsprintf: Do not check address of well-known strings 

We are going to check the address using probe_kernel_address(). It will
be more expensive and it does not make sense for well known address.

This patch splits the string() function. The variant without the check
is then used on locations that handle string constants or strings defined
as local variables.

This patch does not change the existing behavior.

Link: http://lkml.kernel.org/r/20190417115350.20479-4-pmladek@suse.com


To: Rasmus Villemoes <linux@rasmusvillemoes.dk>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: "Tobin C . Harding" <me@tobin.cc>
Cc: Joe Perches <joe@perches.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com>
Cc: linux-kernel@vger.kernel.org
Reviewed-by: default avatarAndy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: default avatarPetr Mladek <pmladek@suse.com>
Reviewed-by: default avatarSergey Senozhatsky <sergey.senozhatsky@gmail.com>
parent 1ac2f978

lib/vsprintf.c

+44 −37
Original line number Diff line number Diff line
@@ -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)
@@ -615,6 +613,15 @@ char *string(char *buf, char *end, const char *s, struct printf_spec spec) 
}



static noinline_for_stack

char *string(char *buf, char *end, const char *s,

	     struct printf_spec spec)

{

	if ((unsigned long)s < PAGE_SIZE)

		s = "(null)";



	return string_nocheck(buf, end, s, spec);

}



char *pointer_string(char *buf, char *end, const void *ptr,

		     struct printf_spec spec)

{
@@ -701,7 +708,7 @@ 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 string_nocheck(buf, end, str, spec);

	}



#ifdef CONFIG_64BIT
@@ -737,7 +744,7 @@ char *restricted_pointer(char *buf, char *end, const void *ptr, 
		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);

			return string_nocheck(buf, end, "pK-error", spec);

		}



		/*
@@ -851,7 +858,7 @@ 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
@@ -937,27 +944,27 @@ char *resource_string(char *buf, char *end, struct resource *res, 


	*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);
@@ -968,21 +975,21 @@ 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
@@ -1150,7 +1157,7 @@ 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
@@ -1313,7 +1320,7 @@ 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
@@ -1324,7 +1331,7 @@ 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
@@ -1386,7 +1393,7 @@ 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
@@ -1421,7 +1428,7 @@ 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
@@ -1522,7 +1529,7 @@ char *uuid_string(char *buf, char *end, const u8 *addr, 


	*p = 0;



	return string(buf, end, uuid, spec);

	return string_nocheck(buf, end, uuid, spec);

}



static noinline_for_stack
@@ -1736,13 +1743,13 @@ 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 +1777,10 @@ 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 string_nocheck(buf, end, "(!OF)", spec);



	if ((unsigned long)dn < PAGE_SIZE)

		return string(buf, end, "(null)", spec);

		return string_nocheck(buf, end, "(null)", spec);



	/* simple case without anything any more format specifiers */

	fmt++;
@@ -1814,7 +1821,7 @@ 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 +1832,10 @@ 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;

			}
@@ -1966,7 +1973,7 @@ char *pointer(const char *fmt, char *buf, char *end, void *ptr, 
		 */

		if (spec.field_width == -1)

			spec.field_width = default_width;

		return string(buf, end, "(null)", spec);

		return string_nocheck(buf, end, "(null)", spec);

	}



	switch (*fmt) {
@@ -2022,7 +2029,7 @@ char *pointer(const char *fmt, char *buf, char *end, void *ptr, 
			case AF_INET6:

				return ip6_addr_string_sa(buf, end, &sa->v6, spec, fmt);

			default:

				return string(buf, end, "(invalid address)", spec);

				return string_nocheck(buf, end, "(invalid address)", spec);

			}}

		}

		break;

CRA Git | Maintained and supported by SUSTech CRA and CCSE