Hello,
I recently pushed a commit (e4d874d88a2ef874a9c2fd7c47d3d3a35ae986e2) that
fixes code being placed in ELF sections that do not have the executable bit
set. This happens when a function is annotated with
__attribute__((section(".some_section"))), or when a section is defined via
inline assembly. In the latter case, it is assumed that the inline assembly
actually contains code, which will not always be the case, but should be the
case the vast majority of the time. When the instruction pointer points to code
in a non-executable section, a segmentation fault occurs.
I have included two files that recreate both of these bugs in
tests/exec_section_in_c.c and tests/exec_section_in_asm.c. The patch is
included on this email.
If anybody has any feedback, I would be curious to know if the blind addition
of the executable flag to sections defined in assembly will be a problem:
particularly if there is widespread usage of the writeable flag for these,
which might elicit segmentation faults from the combined use of the writeable
and executable flags for the same page.
Cheers,
- Jonathan M. Wilbur
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