diff options
Diffstat (limited to 'libgo/go/runtime/checkptr.go')
| -rw-r--r-- | libgo/go/runtime/checkptr.go | 29 |
1 files changed, 28 insertions, 1 deletions
diff --git a/libgo/go/runtime/checkptr.go b/libgo/go/runtime/checkptr.go index e52f7df..ad3ad29 100644 --- a/libgo/go/runtime/checkptr.go +++ b/libgo/go/runtime/checkptr.go @@ -2,6 +2,7 @@ // Use of this source code is governed by a BSD-style // license that can be found in the LICENSE file. +//go:build ignore // +build ignore package runtime @@ -9,6 +10,11 @@ package runtime import "unsafe" func checkptrAlignment(p unsafe.Pointer, elem *_type, n uintptr) { + // nil pointer is always suitably aligned (#47430). + if p == nil { + return + } + // Check that (*[n]elem)(p) is appropriately aligned. // Note that we allow unaligned pointers if the types they point to contain // no pointers themselves. See issue 37298. @@ -18,11 +24,32 @@ func checkptrAlignment(p unsafe.Pointer, elem *_type, n uintptr) { } // Check that (*[n]elem)(p) doesn't straddle multiple heap objects. - if size := n * elem.size; size > 1 && checkptrBase(p) != checkptrBase(add(p, size-1)) { + // TODO(mdempsky): Fix #46938 so we don't need to worry about overflow here. + if checkptrStraddles(p, n*elem.size) { throw("checkptr: converted pointer straddles multiple allocations") } } +// checkptrStraddles reports whether the first size-bytes of memory +// addressed by ptr is known to straddle more than one Go allocation. +func checkptrStraddles(ptr unsafe.Pointer, size uintptr) bool { + if size <= 1 { + return false + } + + // Check that add(ptr, size-1) won't overflow. This avoids the risk + // of producing an illegal pointer value (assuming ptr is legal). + if uintptr(ptr) >= -(size - 1) { + return true + } + end := add(ptr, size-1) + + // TODO(mdempsky): Detect when [ptr, end] contains Go allocations, + // but neither ptr nor end point into one themselves. + + return checkptrBase(ptr) != checkptrBase(end) +} + func checkptrArithmetic(p unsafe.Pointer, originals []unsafe.Pointer) { if 0 < uintptr(p) && uintptr(p) < minLegalPointer { throw("checkptr: pointer arithmetic computed bad pointer value") |