1 files changed, 34 insertions, 46 deletions

diff --git a/lib/vsprintf.c b/lib/vsprintf.c
index 95cd63b43b99..f9cee8e1233c 100644
--- a/lib/vsprintf.c
+++ b/lib/vsprintf.c
@@ -1449,6 +1449,8 @@ int kptr_restrict __read_mostly;
  *        (legacy clock framework) of the clock
  * - 'Cr' For a clock, it prints the current rate of the clock
  *
+ * ** Please update also Documentation/printk-formats.txt when making changes **
+ *
  * Note: The difference between 'S' and 'F' is that on ia64 and ppc64
  * function pointers are really function descriptors, which contain a
  * pointer to the real address.
@@ -1457,7 +1459,7 @@ static noinline_for_stack
 char *pointer(const char *fmt, char *buf, char *end, void *ptr,
               struct printf_spec spec)
 {
-        int default_width = 2 * sizeof(void *) + (spec.flags & SPECIAL ? 2 : 0);
+        const int default_width = 2 * sizeof(void *);
 
         if (!ptr && *fmt != 'K') {
                 /*
@@ -1769,14 +1771,14 @@ qualifier:
 
         case 'n':
                 /*
-                 * Since %n poses a greater security risk than utility, treat
-                 * it as an invalid format specifier. Warn about its use so
-                 * that new instances don't get added.
+                 * Since %n poses a greater security risk than
+                 * utility, treat it as any other invalid or
+                 * unsupported format specifier.
                  */
-                WARN_ONCE(1, "Please remove ignored %%n in '%s'\n", fmt);
                 /* Fall-through */
 
         default:
+                WARN_ONCE(1, "Please remove unsupported %%%c in format string\n", *fmt);
                 spec->type = FORMAT_TYPE_INVALID;
                 return fmt - start;
         }
@@ -1811,41 +1813,16 @@ qualifier:
  * @fmt: The format string to use
  * @args: Arguments for the format string
  *
- * This function follows C99 vsnprintf, but has some extensions:
- * %pS output the name of a text symbol with offset
- * %ps output the name of a text symbol without offset
- * %pF output the name of a function pointer with its offset
- * %pf output the name of a function pointer without its offset
- * %pB output the name of a backtrace symbol with its offset
- * %pR output the address range in a struct resource with decoded flags
- * %pr output the address range in a struct resource with raw flags
- * %pb output the bitmap with field width as the number of bits
- * %pbl output the bitmap as range list with field width as the number of bits
- * %pM output a 6-byte MAC address with colons
- * %pMR output a 6-byte MAC address with colons in reversed order
- * %pMF output a 6-byte MAC address with dashes
- * %pm output a 6-byte MAC address without colons
- * %pmR output a 6-byte MAC address without colons in reversed order
- * %pI4 print an IPv4 address without leading zeros
- * %pi4 print an IPv4 address with leading zeros
- * %pI6 print an IPv6 address with colons
- * %pi6 print an IPv6 address without colons
- * %pI6c print an IPv6 address as specified by RFC 5952
- * %pIS depending on sa_family of 'struct sockaddr *' print IPv4/IPv6 address
- * %piS depending on sa_family of 'struct sockaddr *' print IPv4/IPv6 address
- * %pU[bBlL] print a UUID/GUID in big or little endian using lower or upper
- *   case.
- * %*pE[achnops] print an escaped buffer
- * %*ph[CDN] a variable-length hex string with a separator (supports up to 64
- *           bytes of the input)
- * %pC output the name (Common Clock Framework) or address (legacy clock
- *     framework) of a clock
- * %pCn output the name (Common Clock Framework) or address (legacy clock
- *      framework) of a clock
- * %pCr output the current rate of a clock
- * %n is ignored
+ * This function generally follows C99 vsnprintf, but has some
+ * extensions and a few limitations:
+ *
+ * %n is unsupported
+ * %p* is handled by pointer()
  *
- * ** Please update Documentation/printk-formats.txt when making changes **
+ * See pointer() or Documentation/printk-formats.txt for more
+ * extensive description.
+ *
+ * ** Please update the documentation in both places when making changes **
  *
  * The return value is the number of characters which would
  * be generated for the given input, excluding the trailing
@@ -1944,10 +1921,15 @@ int vsnprintf(char *buf, size_t size, const char *fmt, va_list args)
                         break;
 
                 case FORMAT_TYPE_INVALID:
-                        if (str < end)
-                                *str = '%';
-                        ++str;
-                        break;
+                        /*
+                         * Presumably the arguments passed gcc's type
+                         * checking, but there is no safe or sane way
+                         * for us to continue parsing the format and
+                         * fetching from the va_list; the remaining
+                         * specifiers and arguments would be out of
+                         * sync.
+                         */
+                        goto out;
 
                 default:
                         switch (spec.type) {
@@ -1992,6 +1974,7 @@ int vsnprintf(char *buf, size_t size, const char *fmt, va_list args)
                 }
         }
 
+out:
         if (size > 0) {
                 if (str < end)
                         *str = '\0';
@@ -2189,9 +2172,10 @@ do {									\
 
                 switch (spec.type) {
                 case FORMAT_TYPE_NONE:
-                case FORMAT_TYPE_INVALID:
                 case FORMAT_TYPE_PERCENT_CHAR:
                         break;
+                case FORMAT_TYPE_INVALID:
+                        goto out;
 
                 case FORMAT_TYPE_WIDTH:
                 case FORMAT_TYPE_PRECISION:
@@ -2253,6 +2237,7 @@ do {									\
                 }
         }
 
+out:
         return (u32 *)(PTR_ALIGN(str, sizeof(u32))) - bin_buf;
 #undef save_arg
 }
@@ -2286,7 +2271,7 @@ int bstr_printf(char *buf, size_t size, const char *fmt, const u32 *bin_buf)
         char *str, *end;
         const char *args = (const char *)bin_buf;
 
-        if (WARN_ON_ONCE((int) size < 0))
+        if (WARN_ON_ONCE(size > INT_MAX))
                 return 0;
 
         str = buf;
@@ -2375,12 +2360,14 @@ int bstr_printf(char *buf, size_t size, const char *fmt, const u32 *bin_buf)
                         break;
 
                 case FORMAT_TYPE_PERCENT_CHAR:
-                case FORMAT_TYPE_INVALID:
                         if (str < end)
                                 *str = '%';
                         ++str;
                         break;
 
+                case FORMAT_TYPE_INVALID:
+                        goto out;
+
                 default: {
                         unsigned long long num;
 
@@ -2423,6 +2410,7 @@ int bstr_printf(char *buf, size_t size, const char *fmt, const u32 *bin_buf)
                 } /* switch(spec.type) */
         } /* while(*fmt) */
 
+out:
         if (size > 0) {
                 if (str < end)
                         *str = '\0';