[2.7] bpo-32997: Fix REDOS in fpformat #5984
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The regex to decode a number in fpformat is susceptible to catastrophic backtracking. This is a potential DOS vector if a server is using fpformat on untrusted number strings. Replace it with an equivalent non-vulnerable regex. The match behavior of the new regex is slightly different. This difference is addressed with a follow-up check.
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@serhiy-storchaka Figured you might be a good reviewer? |
Use a simplified regex. Capture the integer part of the number in one group, then strip off leading 0's.
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@serhiy-storchaka fc083d0 addresses your suggestion in the bpo. I agree that this seems like a better approach. |
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The regex to decode a number in fpformat is susceptible to
catastrophic backtracking.
This is a potential DOS vector if a server is using fpformat on
untrusted number strings.
Replace it with an equivalent non-vulnerable regex.
The match behavior of the new regex is slightly different.
This difference is addressed with a follow-up check.
https://bugs.python.org/issue32997