[PATCH 0/2] nptl: Update struct pthread_unwind_buf

[Florian Weimer]

* H. J. Lu:

>> My proposal is still rather hackish, but so is the existing code (the
>
> A pointer to a buffer in user program is passed to libpthread.
> There is a jmp buf in the buffer followed by other fields.  Since
> the size of jmp buf is increased in glibc 2.28, we need to know the
> offset of other fields. Otherwise libpthread may write beyond the
> buffer in user program.  I don't see how symbol versioning can help
> us here since the INTERNAL libpthread functions don't know the
> layout of __pthread_unwind_buf_t of USER programs.

I suggest *not* to increase the size of the jump buffer.

CET markup will not be correct for static libraries compiled against
2.27 or earlier with a CET-enabled toolchain, so this is the only
completely safe approach.