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author | Joe Tsai <joetsai@digital-static.net> | 2021-08-30 10:25:11 -0700 |
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committer | Joe Tsai <joetsai@digital-static.net> | 2021-09-23 16:54:46 +0000 |
commit | 5961134fa5530e8e07b5536b9577e4755ac1e04a (patch) | |
tree | 510d91943cdb456797ff9e034cca5bfbc6b7cdc4 /src/crypto | |
parent | 335e72bcb6a5f670e2b3c65170c4287ca7265934 (diff) | |
download | go-5961134fa5530e8e07b5536b9577e4755ac1e04a.tar.gz go-5961134fa5530e8e07b5536b9577e4755ac1e04a.zip |
crypto: avoid escaping Hash.Sum on generic architectures
For architectures without a specialized implementation (e.g. arm),
the generic implementation allocates because it does:
var block = blockGeneric
which causes the compiler to give up trying to analyze block
even though it is technically only ever one implementation.
Instead of a variable, declare a function that wraps blockGeneric.
We apply this fix to md5, sha1, and sha256,
while sha512 already had the equivalent change.
We add a test to all hashing packages to ensure no allocations.
Credit goes to Cuong Manh Le for more specifically identifying
the problem and Keith Randal for suggesting a concrete solution.
Fixes #48055
Change-Id: I1a6a2e028038e051c83fd72b10a8bf4d210df57d
Reviewed-on: https://go-review.googlesource.com/c/go/+/346209
Trust: Joe Tsai <joetsai@digital-static.net>
Run-TryBot: Joe Tsai <joetsai@digital-static.net>
Reviewed-by: Filippo Valsorda <filippo@golang.org>
Reviewed-by: Cuong Manh Le <cuong.manhle.vn@gmail.com>
Reviewed-by: Keith Randall <khr@golang.org>
TryBot-Result: Go Bot <gobot@golang.org>
Diffstat (limited to 'src/crypto')
-rw-r--r-- | src/crypto/md5/md5_test.go | 14 | ||||
-rw-r--r-- | src/crypto/md5/md5block_generic.go | 4 | ||||
-rw-r--r-- | src/crypto/sha1/sha1_test.go | 14 | ||||
-rw-r--r-- | src/crypto/sha1/sha1block_generic.go | 4 | ||||
-rw-r--r-- | src/crypto/sha256/sha256_test.go | 14 | ||||
-rw-r--r-- | src/crypto/sha256/sha256block_generic.go | 4 | ||||
-rw-r--r-- | src/crypto/sha512/sha512_test.go | 14 |
7 files changed, 65 insertions, 3 deletions
diff --git a/src/crypto/md5/md5_test.go b/src/crypto/md5/md5_test.go index acd456af21..851e7fb10d 100644 --- a/src/crypto/md5/md5_test.go +++ b/src/crypto/md5/md5_test.go @@ -211,6 +211,20 @@ func TestLargeHashes(t *testing.T) { } } +func TestAllocations(t *testing.T) { + in := []byte("hello, world!") + out := make([]byte, 0, Size) + h := New() + n := int(testing.AllocsPerRun(10, func() { + h.Reset() + h.Write(in) + out = h.Sum(out[:0]) + })) + if n > 0 { + t.Errorf("allocs = %d, want 0", n) + } +} + var bench = New() var buf = make([]byte, 1024*1024*8+1) var sum = make([]byte, bench.Size()) diff --git a/src/crypto/md5/md5block_generic.go b/src/crypto/md5/md5block_generic.go index ea4fbcd0b4..23ed75304f 100644 --- a/src/crypto/md5/md5block_generic.go +++ b/src/crypto/md5/md5block_generic.go @@ -9,4 +9,6 @@ package md5 const haveAsm = false -var block = blockGeneric +func block(dig *digest, p []byte) { + blockGeneric(dig, p) +} diff --git a/src/crypto/sha1/sha1_test.go b/src/crypto/sha1/sha1_test.go index c3e6010af1..ab43c7792d 100644 --- a/src/crypto/sha1/sha1_test.go +++ b/src/crypto/sha1/sha1_test.go @@ -210,6 +210,20 @@ func TestLargeHashes(t *testing.T) { } } +func TestAllocations(t *testing.T) { + in := []byte("hello, world!") + out := make([]byte, 0, Size) + h := New() + n := int(testing.AllocsPerRun(10, func() { + h.Reset() + h.Write(in) + out = h.Sum(out[:0]) + })) + if n > 0 { + t.Errorf("allocs = %d, want 0", n) + } +} + var bench = New() var buf = make([]byte, 8192) diff --git a/src/crypto/sha1/sha1block_generic.go b/src/crypto/sha1/sha1block_generic.go index feaba5a23a..105aa31832 100644 --- a/src/crypto/sha1/sha1block_generic.go +++ b/src/crypto/sha1/sha1block_generic.go @@ -7,4 +7,6 @@ package sha1 -var block = blockGeneric +func block(dig *digest, p []byte) { + blockGeneric(dig, p) +} diff --git a/src/crypto/sha256/sha256_test.go b/src/crypto/sha256/sha256_test.go index a2794b015d..702aa0b371 100644 --- a/src/crypto/sha256/sha256_test.go +++ b/src/crypto/sha256/sha256_test.go @@ -289,6 +289,20 @@ func TestLargeHashes(t *testing.T) { } } +func TestAllocations(t *testing.T) { + in := []byte("hello, world!") + out := make([]byte, 0, Size) + h := New() + n := int(testing.AllocsPerRun(10, func() { + h.Reset() + h.Write(in) + out = h.Sum(out[:0]) + })) + if n > 0 { + t.Errorf("allocs = %d, want 0", n) + } +} + var bench = New() var buf = make([]byte, 8192) diff --git a/src/crypto/sha256/sha256block_generic.go b/src/crypto/sha256/sha256block_generic.go index 620c048b93..0f2bf8b231 100644 --- a/src/crypto/sha256/sha256block_generic.go +++ b/src/crypto/sha256/sha256block_generic.go @@ -7,4 +7,6 @@ package sha256 -var block = blockGeneric +func block(dig *digest, p []byte) { + blockGeneric(dig, p) +} diff --git a/src/crypto/sha512/sha512_test.go b/src/crypto/sha512/sha512_test.go index 0e1528fc69..aea772c7da 100644 --- a/src/crypto/sha512/sha512_test.go +++ b/src/crypto/sha512/sha512_test.go @@ -888,6 +888,20 @@ func TestLargeHashes(t *testing.T) { } } +func TestAllocations(t *testing.T) { + in := []byte("hello, world!") + out := make([]byte, 0, Size) + h := New() + n := int(testing.AllocsPerRun(10, func() { + h.Reset() + h.Write(in) + out = h.Sum(out[:0]) + })) + if n > 0 { + t.Errorf("allocs = %d, want 0", n) + } +} + var bench = New() var buf = make([]byte, 8192) |