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Tag testing in QRCodeSetupPayloadParser is wrong #10188

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bzbarsky-apple opened this issue Oct 4, 2021 · 0 comments · Fixed by #13201
Closed

Tag testing in QRCodeSetupPayloadParser is wrong #10188

bzbarsky-apple opened this issue Oct 4, 2021 · 0 comments · Fixed by #13201
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spec Mismatch between spec and implementation

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@bzbarsky-apple
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Problem

Code looks like this:

        const uint8_t tag = static_cast<uint8_t>(TLV::TagNumFromTag(reader.GetTag()));
        VerifyOrReturnError(TLV::IsContextTag(tag) == true || TLV::IsProfileTag(tag) == true, CHIP_ERROR_INVALID_TLV_TAG);

which is nonsense: the tag type tests need to happen on the tag, not the tag number.

But also, why are we allowing profile tags here anyway? The spec doesn't.

Proposed Solution

Align with spec, add tests.

@shana-apple
@bzbarsky-apple bzbarsky-apple added the spec Mismatch between spec and implementation label Oct 4, 2021
bzbarsky-apple added a commit to bzbarsky-apple/connectedhomeip that referenced this issue Dec 22, 2021
@bzbarsky-apple
Fix broken tag handling in QRCodeSetupPayloadParser.
065db81 
The only reason this worked in any way is that TLV::IsProfileTag()
tests true for small integers, so the VerifyOrReturnError was a no-op,
even though we were testing IsContextTag() and IsProfileTag() on the
tag _number_, not the tag.

Per spec, only context tags are allowed here, so just allow those.

Fixes project-chip#10188
@bzbarsky-apple bzbarsky-apple mentioned this issue Dec 22, 2021
Merged
Damian-Nordic pushed a commit that referenced this issue Dec 22, 2021
@bzbarsky-apple
Fix broken tag handling in QRCodeSetupPayloadParser. (#13201)
fcbcac2 
The only reason this worked in any way is that TLV::IsProfileTag()
tests true for small integers, so the VerifyOrReturnError was a no-op,
even though we were testing IsContextTag() and IsProfileTag() on the
tag _number_, not the tag.

Per spec, only context tags are allowed here, so just allow those.

Fixes #10188
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Fix broken tag handling in QRCodeSetupPayloadParser. bzbarsky-apple/connectedhomeip
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