git push后修改错误的commit message

Easiest solution (but please read this whole answer before doing this):

git rebase -i <hash-of-commit-preceding-the-incorrect-one>(这里可以用要改的那次的hash，如果是前一两次也可以用HEAD^或者HEAD^^)

In the editor that opens, change

pick

to

reword

on the line for the incorrect commit.
Save the file and close the editor.
The editor will open again with the incorrect commit message. Fix it.
Save the file and close the editor.

git push --force

to update GitHub.