vppinfra: avoid mem overflow in hash_memory()

Change-Id: Ic81aafd5f378de06e5ea8cdd6a59e07ff1a7afca
Type: improvement
Signed-off-by: Damjan Marion <damarion@cisco.com>

diff --git a/src/vppinfra/hash.c b/src/vppinfra/hash.c
index 7b88692..7c1dcd4 100644 (file)
--- a/src/vppinfra/hash.c
+++ b/src/vppinfra/hash.c
@@ -77,241 +77,53 @@ set_is_user (void *v, uword i, uword is_user)
 
 static u8 *hash_format_pair_default (u8 * s, va_list * args);
 
-#if uword_bits == 64
-
-static inline u64
-zap64 (u64 x, word n)
-{
-#define _(n) (((u64) 1 << (u64) (8*(n))) - (u64) 1)
-  static u64 masks_little_endian[] = {
-    0, _(1), _(2), _(3), _(4), _(5), _(6), _(7),
-  };
-  static u64 masks_big_endian[] = {
-    0, ~_(7), ~_(6), ~_(5), ~_(4), ~_(3), ~_(2), ~_(1),
-  };
-#undef _
-  if (clib_arch_is_big_endian)
-    return x & masks_big_endian[n];
-  else
-    return x & masks_little_endian[n];
-}
-
-/**
- * make address-sanitizer skip this:
- * clib_mem_unaligned + zap64 casts its input as u64, computes a mask
- * according to the input length, and returns the casted maked value.
- * Therefore all the 8 Bytes of the u64 are systematically read, which
- * rightfully causes address-sanitizer to raise an error on smaller inputs.
- *
- * However the invalid Bytes are discarded within zap64(), which is why
- * this can be silenced safely.
- *
- * The above is true *unless* the extra bytes cross a page boundary
- * into unmapped or no-access space, hence the boundary crossing check.
- */
-static inline u64
-hash_memory64 (void *p, word n_bytes, u64 state)
+__clib_export uword
+hash_memory (void *p, word n_bytes, uword state)
 {
-  u64 *q = p;
+  uword last[3] = {};
+  uwordu *q = p;
   u64 a, b, c, n;
-  int page_boundary_crossing;
-  u64 start_addr, end_addr;
-  union
-  {
-    u8 as_u8[8];
-    u64 as_u64;
-  } tmp;
-
-  /*
-   * If the request crosses a 4k boundary, it's not OK to assume
-   * that the zap64 game is safe. 4k is the minimum known page size.
-   */
-  start_addr = (u64) p;
-  end_addr = start_addr + n_bytes + 7;
-  page_boundary_crossing = (start_addr >> 12) != (end_addr >> 12);
-
-  a = b = 0x9e3779b97f4a7c13LL;
-  c = state;
-  n = n_bytes;
-
-  while (n >= 3 * sizeof (u64))
-    {
-      a += clib_mem_unaligned (q + 0, u64);
-      b += clib_mem_unaligned (q + 1, u64);
-      c += clib_mem_unaligned (q + 2, u64);
-      hash_mix64 (a, b, c);
-      n -= 3 * sizeof (u64);
-      q += 3;
-    }
-
-  c += n_bytes;
-  switch (n / sizeof (u64))
-    {
-    case 2:
-      a += clib_mem_unaligned (q + 0, u64);
-      b += clib_mem_unaligned (q + 1, u64);
-      if (n % sizeof (u64))
-       {
-         if (PREDICT_TRUE (page_boundary_crossing == 0))
-           {
-             CLIB_MEM_OVERFLOW_PUSH (q + 2, sizeof (u64));
-             c += zap64 (clib_mem_unaligned (q + 2, u64), n % sizeof (u64))
-                  << 8;
-             CLIB_MEM_OVERFLOW_POP ();
-           }
-         else
-           {
-             clib_memcpy_fast (tmp.as_u8, q + 2, n % sizeof (u64));
-             c += zap64 (tmp.as_u64, n % sizeof (u64)) << 8;
-           }
-       }
-      break;
-
-    case 1:
-      a += clib_mem_unaligned (q + 0, u64);
-      if (n % sizeof (u64))
-       {
-         if (PREDICT_TRUE (page_boundary_crossing == 0))
-           {
-             CLIB_MEM_OVERFLOW_PUSH (q + 1, sizeof (u64));
-             b += zap64 (clib_mem_unaligned (q + 1, u64), n % sizeof (u64));
-             CLIB_MEM_OVERFLOW_POP ();
-           }
-         else
-           {
-             clib_memcpy_fast (tmp.as_u8, q + 1, n % sizeof (u64));
-             b += zap64 (tmp.as_u64, n % sizeof (u64));
-           }
-       }
-      break;
-
-    case 0:
-      if (n % sizeof (u64))
-       {
-         if (PREDICT_TRUE (page_boundary_crossing == 0))
-           {
-             CLIB_MEM_OVERFLOW_PUSH (q + 0, sizeof (u64));
-             a += zap64 (clib_mem_unaligned (q + 0, u64), n % sizeof (u64));
-             CLIB_MEM_OVERFLOW_POP ();
-           }
-         else
-           {
-             clib_memcpy_fast (tmp.as_u8, q, n % sizeof (u64));
-             a += zap64 (tmp.as_u64, n % sizeof (u64));
-           }
-       }
-      break;
-    }
-
-  hash_mix64 (a, b, c);
 
-  return c;
-}
-
-#else /* if uword_bits == 64 */
-
-static inline u32
-zap32 (u32 x, word n)
-{
-#define _(n) (((u32) 1 << (u32) (8*(n))) - (u32) 1)
-  static u32 masks_little_endian[] = {
-    0, _(1), _(2), _(3),
-  };
-  static u32 masks_big_endian[] = {
-    0, ~_(3), ~_(2), ~_(1),
-  };
-#undef _
-  if (clib_arch_is_big_endian)
-    return x & masks_big_endian[n];
-  else
-    return x & masks_little_endian[n];
-}
-
-static inline u32
-hash_memory32 (void *p, word n_bytes, u32 state)
-{
-  u32 *q = p;
-  u32 a, b, c, n;
-
-  a = b = 0x9e3779b9;
+  a = b = (uword_bits == 64) ? 0x9e3779b97f4a7c13LL : 0x9e3779b9;
   c = state;
   n = n_bytes;
 
-  while (n >= 3 * sizeof (u32))
+  while (n >= 3 * sizeof (uword))
     {
-      a += clib_mem_unaligned (q + 0, u32);
-      b += clib_mem_unaligned (q + 1, u32);
-      c += clib_mem_unaligned (q + 2, u32);
-      hash_mix32 (a, b, c);
-      n -= 3 * sizeof (u32);
+      a += q[0];
+      b += q[1];
+      c += q[2];
+      hash_mix (a, b, c);
+      n -= 3 * sizeof (uword);
       q += 3;
     }
 
   c += n_bytes;
-  switch (n / sizeof (u32))
-    {
-    case 2:
-      a += clib_mem_unaligned (q + 0, u32);
-      b += clib_mem_unaligned (q + 1, u32);
-      if (n % sizeof (u32))
-       c += zap32 (clib_mem_unaligned (q + 2, u32), n % sizeof (u32)) << 8;
-      break;
 
-    case 1:
-      a += clib_mem_unaligned (q + 0, u32);
-      if (n % sizeof (u32))
-       b += zap32 (clib_mem_unaligned (q + 1, u32), n % sizeof (u32));
-      break;
-
-    case 0:
-      if (n % sizeof (u32))
-       a += zap32 (clib_mem_unaligned (q + 0, u32), n % sizeof (u32));
-      break;
+  if (n > 0)
+    {
+      clib_memcpy_fast (&last, q, n);
+      a += last[0];
+      b += last[1];
+      c += last[2];
     }
 
-  hash_mix32 (a, b, c);
+  hash_mix (a, b, c);
 
   return c;
 }
-#endif
-
-__clib_export uword
-hash_memory (void *p, word n_bytes, uword state)
-{
-  uword *q = p;
-
-#if uword_bits == 64
-  return hash_memory64 (q, n_bytes, state);
-#else
-  return hash_memory32 (q, n_bytes, state);
-#endif
-}
-
-#if uword_bits == 64
-always_inline uword
-hash_uword (uword x)
-{
-  u64 a, b, c;
 
-  a = b = 0x9e3779b97f4a7c13LL;
-  c = 0;
-  a += x;
-  hash_mix64 (a, b, c);
-  return c;
-}
-#else
 always_inline uword
 hash_uword (uword x)
 {
-  u32 a, b, c;
+  uword a, b, c;
 
-  a = b = 0x9e3779b9;
+  a = b = (uword_bits == 64) ? 0x9e3779b97f4a7c13LL : 0x9e3779b9;
   c = 0;
   a += x;
-  hash_mix32 (a, b, c);
+  hash_mix (a, b, c);
   return c;
 }
-#endif
 
 /* Call sum function.  Hash code will be sum function value
    modulo the prime length of the hash table. */

diff --git a/src/vppinfra/hash.h b/src/vppinfra/hash.h
index f5735bc..968c778 100644 (file)
--- a/src/vppinfra/hash.h
+++ b/src/vppinfra/hash.h
@@ -527,6 +527,12 @@ do {                                               \
 #define hash_mix64_step_3(a,b,c) hash_mix_step(a,b,c,35,49,11)
 #define hash_mix64_step_4(a,b,c) hash_mix_step(a,b,c,12,18,22)
 
+#if uword_bits == 64
+#define hash_mix(a, b, c) hash_mix64 (a, b, c)
+#else
+#define hash_mix(a, b, c) hash_mix32 (a, b, c)
+#endif
+
 /* Hash function based on that of Bob Jenkins (bob_jenkins@compuserve.com).
    Thanks, Bob. */
 #define hash_mix64(a0,b0,c0)                   \

diff --git a/src/vppinfra/types.h b/src/vppinfra/types.h
index 34b8b07..24dd5b3 100644 (file)
--- a/src/vppinfra/types.h
+++ b/src/vppinfra/types.h
@@ -171,6 +171,8 @@ typedef u64 u64u __attribute__ ((aligned (1), __may_alias__));
 typedef i16 i16u __attribute__ ((aligned (1), __may_alias__));
 typedef i32 i32u __attribute__ ((aligned (1), __may_alias__));
 typedef i64 i64u __attribute__ ((aligned (1), __may_alias__));
+typedef word wordu __attribute__ ((aligned (1), __may_alias__));
+typedef uword uwordu __attribute__ ((aligned (1), __may_alias__));
 
 #endif /* included_clib_types_h */