Messages in this thread | | | Date | Tue, 5 Dec 2017 20:09:35 +0000 | From | Russell King - ARM Linux <> | Subject | Re: [PATCH] Arm: mm: ftrace: Only set text back to ro after kernel has been marked ro |
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On Tue, Dec 05, 2017 at 11:35:59AM -0800, Kees Cook wrote: > We don't _need_ to, but they're all contiguous, so the ro_perms array > used by set_kernel_text_*() is actually only a single entry: > > static struct section_perm ro_perms[] = { > /* Make kernel code and rodata RX (set RO). */ > { > .name = "text/rodata RO", > .start = (unsigned long)_stext, > .end = (unsigned long)__init_begin, > ...
Well, they may not be contiguous - it depends on DEBUG_ALIGN_RODATA.
Either way, we have __start_rodata_section_aligned, which is either the start of the read-only data section, or the start of the first section beyond __start_rodata if DEBUG_ALIGN_RODATA is not set.
Given that __start_rodata_section_aligned will always be less than __init_begin, is there any reason not to make the above end at __start_rodata_section_aligned, thereby allowing more of the read-only data (in the case of DEBUG_ALIGN_RODATA=n) or all of the read-only data (in the case of DEBUG_ALIGN_RODATA=y) to remain write-protected?
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