Update hkdf.c to avoid potentially vulnerable code pattern #20990
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openssl-machine
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hold: cla required
paulidale
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May 17, 2023
paulidale
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May 17, 2023
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branch: master
The expression "if (a+b>c) a=c-b" is incorrect if "a+b" overflows. It should be replaced by "if (a>c-b) a=c-b", which avoids the potential overflow and is much easier to understand. This pattern is the root cause of CVE-2022-37454, a buffer overflow vulnerability in the "official" SHA-3 implementation. It has been confirmed that the addition in https://github.com/openssl/openssl/blob/master/providers/implementations/kdfs/hkdf.c#L534 cannot overflow. So this is only a minor change proposal to avoid a potentially vulnerable code pattern and to improve readability. More information: github/codeql#12036 (comment) CLA: trivial
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Took the liberty of squashing everything down neatly. This should fix the CLA tag. |
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severity: fips change
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Hi @paulidale, Thanks for looking into this and for fixing the CLA tag! Sorry for messing up the pull request... |
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No problem, we've all done similar and will again. |
t8m
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May 18, 2023
t8m
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approval: done
openssl-machine
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approval: ready to merge
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This pull request is ready to merge |
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Merged to master, 3.1, and 3.0 branches. Thank you for your contribution. |
openssl-machine
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May 19, 2023
The expression "if (a+b>c) a=c-b" is incorrect if "a+b" overflows. It should be replaced by "if (a>c-b) a=c-b", which avoids the potential overflow and is much easier to understand. This pattern is the root cause of CVE-2022-37454, a buffer overflow vulnerability in the "official" SHA-3 implementation. It has been confirmed that the addition in https://github.com/openssl/openssl/blob/master/providers/implementations/kdfs/hkdf.c#L534 cannot overflow. So this is only a minor change proposal to avoid a potentially vulnerable code pattern and to improve readability. More information: github/codeql#12036 (comment) CLA: trivial Reviewed-by: Paul Dale <pauli@openssl.org> Reviewed-by: Tomas Mraz <tomas@openssl.org> (Merged from #20990) (cherry picked from commit 56a51b5)
openssl-machine
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this pull request
May 19, 2023
The expression "if (a+b>c) a=c-b" is incorrect if "a+b" overflows. It should be replaced by "if (a>c-b) a=c-b", which avoids the potential overflow and is much easier to understand. This pattern is the root cause of CVE-2022-37454, a buffer overflow vulnerability in the "official" SHA-3 implementation. It has been confirmed that the addition in https://github.com/openssl/openssl/blob/master/providers/implementations/kdfs/hkdf.c#L534 cannot overflow. So this is only a minor change proposal to avoid a potentially vulnerable code pattern and to improve readability. More information: github/codeql#12036 (comment) CLA: trivial Reviewed-by: Paul Dale <pauli@openssl.org> Reviewed-by: Tomas Mraz <tomas@openssl.org> (Merged from #20990) (cherry picked from commit 56a51b5)
openssl-machine
pushed a commit
that referenced
this pull request
May 19, 2023
The expression "if (a+b>c) a=c-b" is incorrect if "a+b" overflows. It should be replaced by "if (a>c-b) a=c-b", which avoids the potential overflow and is much easier to understand. This pattern is the root cause of CVE-2022-37454, a buffer overflow vulnerability in the "official" SHA-3 implementation. It has been confirmed that the addition in https://github.com/openssl/openssl/blob/master/providers/implementations/kdfs/hkdf.c#L534 cannot overflow. So this is only a minor change proposal to avoid a potentially vulnerable code pattern and to improve readability. More information: github/codeql#12036 (comment) CLA: trivial Reviewed-by: Paul Dale <pauli@openssl.org> Reviewed-by: Tomas Mraz <tomas@openssl.org> (Merged from #20990)
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The expression
if (a+b>c) a=c-bis incorrect ifa+boverflows. It should be replaced byif (a>c-b) a=c-b, which avoids the potential overflow and is much easier to understand. This pattern is the root cause of CVE-2022-37454, a buffer overflow vulnerability in the "official" SHA-3 implementation.It has been confirmed that the addition in hkdf.c:534 cannot overflow. So this is only a minor proposed change to avoid potentially vulnerable code patterns and to improve readability. More information: github/codeql#12036 (comment)