math/big: fix shift for recursive division

The previous s value could cause a crash
for certain inputs.

Will check in tests and documentation improvements later.

Thanks to the Go Ethereum team and the OSS-Fuzz project for reporting this.
Thanks to Rémy Oudompheng and Robert Griesemer for their help
developing and validating the fix.

Fixes CVE-2020-28362

Change-Id: Ibbf455c4436bcdb07c84a34fa6551fb3422356d3
Reviewed-by: Roland Shoemaker <>
Reviewed-by: Filippo Valsorda <>
Trust: Katie Hockman <>
Trust: Roland Shoemaker <>
Run-TryBot: Katie Hockman <>
Reviewed-by: Roland Shoemaker <>
TryBot-Result: Go Bot <>
1 file changed
tree: 99c236777e152cea208b785f6263f0b41bb540a1
  1. .gitattributes
  2. .github/
  3. .gitignore
  11. api/
  12. doc/
  13. favicon.ico
  14. lib/
  15. misc/
  16. robots.txt
  17. src/
  18. test/

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