diff options
| author | khr@golang.org <khr@golang.org> | 2024-04-15 17:52:20 -0700 |
|---|---|---|
| committer | Keith Randall <khr@golang.org> | 2024-04-19 17:38:07 +0000 |
| commit | ef2f3391da20e4aca689033045c0d00fddd0b190 (patch) | |
| tree | 5bab32ea9a1f7bca26d60c6d987557a1fdfd9df8 /src/runtime/hash64.go | |
| parent | 2b82a4f488179a62a69dd318ea62f0624641ae63 (diff) | |
| download | go-ef2f3391da20e4aca689033045c0d00fddd0b190.tar.gz go-ef2f3391da20e4aca689033045c0d00fddd0b190.zip | |
runtime: make it harder to find collisions in the 64-bit fallback hash
Currently the first argument to mix() can be set by an attacker, as it
is just the input bytes xored by some constants. That lets an attacker
set the value being multipled by to 0. That can lead to lots of
collisions. To fix, xor the first argument with the process-wide seed,
so the magic collision-generating value isn't a constant known to the
attacker. (Maybe there's a timing attack that could figure out the
process-wide seed, but that's a much harder attack.)
Fixes #66841
Change-Id: I33e073c78355d1cee08660de52074e6ccc38b426
Reviewed-on: https://go-review.googlesource.com/c/go/+/579115
Reviewed-by: M Zhuo <mengzhuo1203@gmail.com>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Reviewed-by: Keith Randall <khr@google.com>
Reviewed-by: Michael Pratt <mpratt@google.com>
Diffstat (limited to 'src/runtime/hash64.go')
| -rw-r--r-- | src/runtime/hash64.go | 14 |
1 files changed, 7 insertions, 7 deletions
diff --git a/src/runtime/hash64.go b/src/runtime/hash64.go index 2864a4b963..bd16b7cd96 100644 --- a/src/runtime/hash64.go +++ b/src/runtime/hash64.go @@ -50,32 +50,32 @@ func memhashFallback(p unsafe.Pointer, seed, s uintptr) uintptr { seed1 := seed seed2 := seed for ; l > 48; l -= 48 { - seed = mix(r8(p)^m2, r8(add(p, 8))^seed) - seed1 = mix(r8(add(p, 16))^m3, r8(add(p, 24))^seed1) - seed2 = mix(r8(add(p, 32))^m4, r8(add(p, 40))^seed2) + seed = mix(r8(p)^hashkey[1]^m2, r8(add(p, 8))^seed) + seed1 = mix(r8(add(p, 16))^hashkey[2]^m3, r8(add(p, 24))^seed1) + seed2 = mix(r8(add(p, 32))^hashkey[3]^m4, r8(add(p, 40))^seed2) p = add(p, 48) } seed ^= seed1 ^ seed2 } for ; l > 16; l -= 16 { - seed = mix(r8(p)^m2, r8(add(p, 8))^seed) + seed = mix(r8(p)^hashkey[1]^m2, r8(add(p, 8))^seed) p = add(p, 16) } a = r8(add(p, l-16)) b = r8(add(p, l-8)) } - return mix(m5^s, mix(a^m2, b^seed)) + return mix(m5^s, mix(a^hashkey[1]^m2, b^seed)) } func memhash32Fallback(p unsafe.Pointer, seed uintptr) uintptr { a := r4(p) - return mix(m5^4, mix(a^m2, a^seed^hashkey[0]^m1)) + return mix(m5^4, mix(a^hashkey[1]^m2, a^seed^hashkey[0]^m1)) } func memhash64Fallback(p unsafe.Pointer, seed uintptr) uintptr { a := r8(p) - return mix(m5^8, mix(a^m2, a^seed^hashkey[0]^m1)) + return mix(m5^8, mix(a^hashkey[1]^m2, a^seed^hashkey[0]^m1)) } func mix(a, b uintptr) uintptr { |