fix clib_mem_unaligned() invalid read
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, and
the invalid ones are discarded.
For example, for a 5-Bytes string, we will do an invalid read of size 3,
even though those 3 Bytes are never used.
This patch proposes to only read what we have at the cost of reading as
a u64 in one call, but that way, we do not trigger an invalid read
error.
Change-Id: I3e0b31c4113d9c8e53aa5fa3d3d396ec80f06a27
Signed-off-by: Gabriel Ganne <gabriel.ganne@enea.com>
diff --git a/src/vppinfra/hash.c b/src/vppinfra/hash.c
index 062ad88..b3db9f8 100644
--- a/src/vppinfra/hash.c
+++ b/src/vppinfra/hash.c
@@ -80,20 +80,24 @@
#if uword_bits == 64
static inline u64
-zap64 (u64 x, word n)
+get_unaligned_as_u64 (void const *data, int 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 _
+ int i;
+ u64 r = 0;
+ u8 const *p = (u8 const *) data;
+
if (clib_arch_is_big_endian)
- return x & masks_big_endian[n];
+ {
+ for (i = 0; i < n; i++)
+ r |= ((u64) ((*(p + i)) << (u8) (1 << (8 - i))));
+ }
else
- return x & masks_little_endian[n];
+ {
+ for (i = 0; i < n; i++)
+ r |= ((u64) ((*(p + i)) << (u8) (1 << i)));
+ }
+
+ return r;
}
static inline u64
@@ -122,19 +126,16 @@
case 2:
a += clib_mem_unaligned (q + 0, u64);
b += clib_mem_unaligned (q + 1, u64);
- if (n % sizeof (u64))
- c += zap64 (clib_mem_unaligned (q + 2, u64), n % sizeof (u64)) << 8;
+ c += get_unaligned_as_u64 (q + 2, n % sizeof (u64)) << 8;
break;
case 1:
a += clib_mem_unaligned (q + 0, u64);
- if (n % sizeof (u64))
- b += zap64 (clib_mem_unaligned (q + 1, u64), n % sizeof (u64));
+ b += get_unaligned_as_u64 (q + 1, n % sizeof (u64));
break;
case 0:
- if (n % sizeof (u64))
- a += zap64 (clib_mem_unaligned (q + 0, u64), n % sizeof (u64));
+ a += get_unaligned_as_u64 (q + 0, n % sizeof (u64));
break;
}