bash.exe、mintty.exe hung, hacking way cause app hung in msys-2.0.dll

[cssxn]

msys-2.0.dll which from cygwin project that using a hacking way to find the current dir path.

see,

msys2-runtime/winsup/cygwin/path.cc

Line 4859 in 0eeda3e

const uint8_t *rcall = (const uint8_t *) memchr (get_dir, 0xe8, 80);

the app hung when RtlGetCurrentDirectory_U is already hooked by other dll, and the opcode operator has an 0xE8,

that make this func find_fast_cwd_pointer get wrong lock pointer from PEB.

after that. when access the wrong pointer cause app hung or acccess violation.

this bug was fixed since April 2025 in cygwin project, see below

https://github.com/cygwin/cygwin/blob/b41e3b652c4215556a62a2f47e8f8f11553fa550/winsup/cygwin/x86_64/fastcwd.cc#L40

It would be greate to merge this fix;

this effect a lot of sofware which dependence on msys-2.0.dll

[dscho]

Commit c23bcc8 has indeed been integrated into Cygwin's main branch. However, you will notice that it has not been in any official release of Cygwin as of time of writing.