Kernel related (?) user space crash at ARM11 MPCore
Jamie Lokier
jamie at shareable.org
Mon Sep 21 18:25:47 EDT 2009
Russell King - ARM Linux wrote:
> > Hopefully it's clear that munmap of the region, followed by mmap
> > PROT_READ|PROTE_EXEC to restore the mapping with different permissions
> > (when it has a backing file) - hopefully it's clear that _that_ will
> > do the needed I-cache flush.
>
> Not necessarily, especially if the file is mapped using MAP_PRIVATE.
If the answer is not necessarily for MAP_SHARED, then we're in trouble
when someone does
internal_untar("some_files.tar.gz");
-> Uses open/ftruncate/mmap(PROT_WRITE)/close to write the files.
dlopen("some_files/code.so")
code(...)
Which strikes as the sort of thing people might do these days.
For MAP_PRIVATE... I'm not sure if that will trip people up or not.
-- Jamie
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