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encoding/binary: Size panics when passed a nil pointer to a slice #60892

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lmb opened this issue Jun 20, 2023 · 3 comments
Closed

encoding/binary: Size panics when passed a nil pointer to a slice #60892

lmb opened this issue Jun 20, 2023 · 3 comments
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NeedsFix The path to resolution is known, but the work has not been done.
Milestone
Go1.21

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@lmb
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lmb commented Jun 20, 2023

What version of Go are you using (go version)?

1.20

Does this issue reproduce with the latest release?

Yes.

What did you do?

Pass (*[]byte)(nil) to binary.Size.

https://go.dev/play/p/eKvs4FJHkxy

What did you expect to see?

The function should return -1.

What did you see instead?

The function panicked instead:

panic: reflect: call of reflect.Value.Type on zero Value

goroutine 1 [running]:
reflect.Value.typeSlow({0x0?, 0x0?, 0xc0000406c8?})
	/usr/local/go-faketime/src/reflect/value.go:2610 +0x12e
reflect.Value.Type(...)
	/usr/local/go-faketime/src/reflect/value.go:2605
encoding/binary.dataSize({0x0?, 0x0?, 0x60?})
	/usr/local/go-faketime/src/encoding/binary/binary.go:490 +0x17f
encoding/binary.Size({0x4873c0?, 0x0?})
	/usr/local/go-faketime/src/encoding/binary/binary.go:463 +0xb9
main.main()
	/tmp/sandbox3549274882/prog.go:11 +0x25
@gopherbot
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Change https://go.dev/cl/504575 mentions this issue: encoding/binary: on invalid type return -1 from Size

@bcmills bcmills added the NeedsFix The path to resolution is known, but the work has not been done. label Jun 20, 2023
@dmitshur dmitshur added this to the Go1.21 milestone Jun 21, 2023
@lmb
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lmb commented Jul 4, 2023

Could this get a backport to v1.20?

@ianlancetaylor
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We normally only backport serious bugs that have no workaround. This bug has a simple workaround, so it's not eligible for backporting.

bradfitz pushed a commit to tailscale/go that referenced this issue Jul 15, 2023
@ianlancetaylor @bradfitz
encoding/binary: on invalid type return -1 from Size
12fd4f5 
Size is defined as returning -1 if the type is not fixed-size.
Before this CL cases like Size((*[]int)(nil)) would crash.

Fixes golang#60892

Change-Id: Iee8e20a0aee24b542b78cb4160c3b2c5a3eb02c2
Reviewed-on: https://go-review.googlesource.com/c/go/+/504575
Auto-Submit: Ian Lance Taylor <iant@golang.org>
Run-TryBot: Ian Lance Taylor <iant@golang.org>
Reviewed-by: Robert Griesemer <gri@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
Reviewed-by: Bryan Mills <bcmills@google.com>
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