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path: root/src/runtime/checkptr.go
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2021-07-28runtime: don't crash on nil pointers in checkptrAlignmentMatthew Dempsky
Ironically, checkptrAlignment had a latent case of bad pointer arithmetic: if ptr is nil, then `add(ptr, size-1)` might produce an illegal pointer value. The fix is to simply check for nil at the top of checkptrAlignment, and short-circuit if so. This CL also adds a more explicit bounds check in checkptrStraddles, rather than relying on `add(ptr, size-1)` to wrap around. I don't think this is necessary today, but it seems prudent to be careful. Fixes #47430. Change-Id: I5c50b2f7f41415dbebbd803e1b8e7766ca95e1fd Reviewed-on: https://go-review.googlesource.com/c/go/+/338029 Trust: Matthew Dempsky <mdempsky@google.com> Run-TryBot: Matthew Dempsky <mdempsky@google.com> TryBot-Result: Go Bot <gobot@golang.org> Reviewed-by: Keith Randall <khr@golang.org>
2021-06-28cmd/compile,runtime: change unsafe.Slice((*T)(nil), 0) to return []T(nil)Matthew Dempsky
This CL removes the unconditional OCHECKNIL check added in walkUnsafeSlice by instead passing it as a pointer to runtime.unsafeslice, and hiding the check behind a `len == 0` check. While here, this CL also implements checkptr functionality for unsafe.Slice and disallows use of unsafe.Slice with //go:notinheap types. Updates #46742. Change-Id: I743a445ac124304a4d7322a7fe089c4a21b9a655 Reviewed-on: https://go-review.googlesource.com/c/go/+/331070 Run-TryBot: Matthew Dempsky <mdempsky@google.com> TryBot-Result: Go Bot <gobot@golang.org> Trust: Matthew Dempsky <mdempsky@google.com> Reviewed-by: Keith Randall <khr@golang.org>
2020-03-17runtime: don't report a pointer alignment error for pointer-free base typeKeith Randall
Fixes #37298 Change-Id: I8ba9c8b106e16cea7dd25473c7390b0f2ba9a1a5 Reviewed-on: https://go-review.googlesource.com/c/go/+/223781 Run-TryBot: Keith Randall <khr@golang.org> Reviewed-by: Ian Lance Taylor <iant@golang.org> Reviewed-by: Matthew Dempsky <mdempsky@google.com> TryBot-Result: Gobot Gobot <gobot@golang.org>
2020-03-12runtime: emit more specific errors from checkptrJohan Jansson
Update error messages for pointer alignment checks and pointer arithmetic checks so that each type of error has a unique error message. Fixes #37488 Change-Id: Ida2c2fa3f041a3307d665879a463f9e8f2c1fd03 Reviewed-on: https://go-review.googlesource.com/c/go/+/223037 Reviewed-by: Matthew Dempsky <mdempsky@google.com> Run-TryBot: Matthew Dempsky <mdempsky@google.com> TryBot-Result: Gobot Gobot <gobot@golang.org>
2020-01-09runtime: change checkptr to use throw instead of panicMatthew Dempsky
Updates #34964. Change-Id: I5afb2c1e77a9a47358a1d0d108c4a787d7172b94 Reviewed-on: https://go-review.googlesource.com/c/go/+/214217 Run-TryBot: Matthew Dempsky <mdempsky@google.com> TryBot-Result: Gobot Gobot <gobot@golang.org> Reviewed-by: Austin Clements <austin@google.com>
2019-10-22runtime: fix -d=checkptr failure for testing/quickMatthew Dempsky
This CL extends checkptrBase to recognize pointers into the stack and data/bss sections. I was meaning to do this eventually anyway, but it's also an easy way to workaround #35068. Updates #35068. Change-Id: Ib47f0aa800473a4fbc249da52ff03bec32c3ebe2 Reviewed-on: https://go-review.googlesource.com/c/go/+/202639 Run-TryBot: Matthew Dempsky <mdempsky@google.com> TryBot-Result: Gobot Gobot <gobot@golang.org> Reviewed-by: Austin Clements <austin@google.com>
2019-10-22runtime: somewhat better checkptr error messagesMatthew Dempsky
They're still lacking in details, but at least better than being printed as raw interface values. Updates #22218. Change-Id: I4fd813253afdd6455c0c9b5a05c61659805abad1 Reviewed-on: https://go-review.googlesource.com/c/go/+/202677 Run-TryBot: Matthew Dempsky <mdempsky@google.com> TryBot-Result: Gobot Gobot <gobot@golang.org> Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
2019-10-21cmd/compile: recognize (*[Big]T)(ptr)[:n:m] pattern for -d=checkptrMatthew Dempsky
A common idiom for turning an unsafe.Pointer into a slice is to write: s := (*[Big]T)(ptr)[:n:m] This technically violates Go's unsafe pointer rules (rule #1 says T2 can't be bigger than T1), but it's fairly common and not too difficult to recognize, so might as well allow it for now so we can make progress on #34972. This should be revisited if #19367 is accepted. Updates #22218. Updates #34972. Change-Id: Id824e2461904e770910b6e728b4234041d2cc8bc Reviewed-on: https://go-review.googlesource.com/c/go/+/201839 Run-TryBot: Matthew Dempsky <mdempsky@google.com> TryBot-Result: Gobot Gobot <gobot@golang.org> Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
2019-10-17cmd/compile: detect unsafe conversions from smaller to larger typesMatthew Dempsky
This CL extends the runtime instrumentation for (*T)(ptr) to also check that the first and last bytes of *(*T)(ptr) are part of the same heap object. Updates #22218. Updates #34959. Change-Id: I2c8063fe1b7fe6e6145e41c5654cb64dd1c9dd41 Reviewed-on: https://go-review.googlesource.com/c/go/+/201778 Run-TryBot: Matthew Dempsky <mdempsky@google.com> Reviewed-by: Keith Randall <khr@golang.org> Reviewed-by: Cuong Manh Le <cuong.manhle.vn@gmail.com> TryBot-Result: Gobot Gobot <gobot@golang.org>
2019-10-17cmd/compile: add -d=checkptr to validate unsafe.Pointer rulesMatthew Dempsky
This CL adds -d=checkptr as a compile-time option for adding instrumentation to check that Go code is following unsafe.Pointer safety rules dynamically. In particular, it currently checks two things: 1. When converting unsafe.Pointer to *T, make sure the resulting pointer is aligned appropriately for T. 2. When performing pointer arithmetic, if the result points to a Go heap object, make sure we can find an unsafe.Pointer-typed operand that pointed into the same object. These checks are currently disabled for the runtime, and can also be disabled through a new //go:nocheckptr annotation. The latter is necessary for functions like strings.noescape, which intentionally violate safety rules to workaround escape analysis limitations. Fixes #22218. Change-Id: If5a51273881d93048f74bcff10a3275c9c91da6a Reviewed-on: https://go-review.googlesource.com/c/go/+/162237 Run-TryBot: Matthew Dempsky <mdempsky@google.com> TryBot-Result: Gobot Gobot <gobot@golang.org> Reviewed-by: Keith Randall <khr@golang.org>
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