Do not create invalid pointers in C code of string functions.

Some of the x86 string functions create pointers based on input strings
that may be outside of the input strings.  When this happens in C code,
the compiler can potentially detect this, leading to warnings in
application code when those string functions are inlined.  Perform those
operations in the assembly code instead of the C code to fix this.

diff --git a/ChangeLog b/ChangeLog
index 15deac7..c6c3356 100644 (file)
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,11 @@
+2015-07-07  Torvald Riegel  <triegel@redhat.com>
+
+       [BZ #18633]
+       * sysdeps/x86/bits/string.h (__memmove_g): Do not create invalid
+       pointer in C code.
+       (__strcat_c): Likewise.
+       (__strcat_g): Likewise.
+
 2015-07-07  Cyril Hrubis <chrubis@suse.cz>
 
        [BZ #18592]

diff --git a/NEWS b/NEWS
index 53dea6e..569a7d6 100644 (file)
--- a/NEWS
+++ b/NEWS
@@ -25,7 +25,7 @@ Version 2.22
   18496, 18497, 18498, 18502, 18507, 18512, 18513, 18519, 18520, 18522,
   18527, 18528, 18529, 18530, 18532, 18533, 18534, 18536, 18539, 18540,
   18542, 18544, 18545, 18546, 18547, 18549, 18553, 18558, 18569, 18583,
-  18585, 18586, 18592, 18593, 18594, 18602, 18612, 18613, 18619.
+  18585, 18586, 18592, 18593, 18594, 18602, 18612, 18613, 18619, 18633.
 
 * Cache information can be queried via sysconf() function on s390 e.g. with
   _SC_LEVEL1_ICACHE_SIZE as argument.

diff --git a/sysdeps/x86/bits/string.h b/sysdeps/x86/bits/string.h
index a117f6b..4973620 100644 (file)
--- a/sysdeps/x86/bits/string.h
+++ b/sysdeps/x86/bits/string.h
@@ -176,13 +176,15 @@ __memmove_g (void *__dest, const void *__src, size_t __n)
         "m" ( *(struct { __extension__ char __x[__n]; } *)__src));
   else
     __asm__ __volatile__
-      ("std\n\t"
+      ("decl %1\n\t"
+       "decl %2\n\t"
+       "std\n\t"
        "rep; movsb\n\t"
        "cld"
        : "=&c" (__d0), "=&S" (__d1), "=&D" (__d2),
         "=m" ( *(struct { __extension__ char __x[__n]; } *)__dest)
-       : "0" (__n), "1" (__n - 1 + (const char *) __src),
-        "2" (__n - 1 + (char *) __tmp),
+       : "0" (__n), "1" (__n + (const char *) __src),
+        "2" (__n + (char *) __tmp),
         "m" ( *(struct { __extension__ char __x[__n]; } *)__src));
   return __dest;
 }
@@ -999,9 +1001,10 @@ __strcat_c (char *__dest, const char __src[], size_t __srclen)
      : "cc");
   --__tmp;
 # else
-  register char *__tmp = __dest - 1;
+  register char *__tmp = __dest;
   __asm__ __volatile__
-    ("1:\n\t"
+    ("decl     %0\n\t"
+     "1:\n\t"
      "incl     %0\n\t"
      "cmpb     $0,(%0)\n\t"
      "jne      1b\n"
@@ -1020,10 +1023,11 @@ __STRING_INLINE char *__strcat_g (char *__dest, const char *__src);
 __STRING_INLINE char *
 __strcat_g (char *__dest, const char *__src)
 {
-  register char *__tmp = __dest - 1;
+  register char *__tmp = __dest;
   register char __dummy;
   __asm__ __volatile__
-    ("1:\n\t"
+    ("decl     %1\n\t"
+     "1:\n\t"
      "incl     %1\n\t"
      "cmpb     $0,(%1)\n\t"
      "jne      1b\n"