| Message ID | 20181106214404.2497-2-ard.biesheuvel@linaro.org (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | get rid of writable linear aliases of read-only vmalloc mappings | expand |
On Tue, Nov 06, 2018 at 10:44:03PM +0100, Ard Biesheuvel wrote: > Call vm_unmap_aliases() every time we apply any changes to permission > attributes of mappings in the vmalloc region. This avoids any potential > issues resulting from lingering writable or executable aliases of > mappings that should be read-only or non-executable, respectively. > > Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org> > --- > arch/arm64/mm/pageattr.c | 6 ++++++ > 1 file changed, 6 insertions(+) > > diff --git a/arch/arm64/mm/pageattr.c b/arch/arm64/mm/pageattr.c > index a56359373d8b..f8cf5bc1d1f8 100644 > --- a/arch/arm64/mm/pageattr.c > +++ b/arch/arm64/mm/pageattr.c > @@ -93,6 +93,12 @@ static int change_memory_common(unsigned long addr, int numpages, > if (!numpages) > return 0; > > + /* > + * Get rid of potentially aliasing lazily unmapped vm areas that may > + * have permissions set that deviate from the ones we are setting here. > + */ > + vm_unmap_aliases(); So this might_sleep(), which I don't think is currently the case for our set_memory_XX() functions. However, a quick look at the existing callsites indicates that's ok and matches the x86 implementation, so: Acked-by: Will Deacon <will.deacon@arm.com> Will
diff --git a/arch/arm64/mm/pageattr.c b/arch/arm64/mm/pageattr.c index a56359373d8b..f8cf5bc1d1f8 100644 --- a/arch/arm64/mm/pageattr.c +++ b/arch/arm64/mm/pageattr.c @@ -93,6 +93,12 @@ static int change_memory_common(unsigned long addr, int numpages, if (!numpages) return 0; + /* + * Get rid of potentially aliasing lazily unmapped vm areas that may + * have permissions set that deviate from the ones we are setting here. + */ + vm_unmap_aliases(); + return __change_memory_common(start, size, set_mask, clear_mask); }
Call vm_unmap_aliases() every time we apply any changes to permission attributes of mappings in the vmalloc region. This avoids any potential issues resulting from lingering writable or executable aliases of mappings that should be read-only or non-executable, respectively. Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org> --- arch/arm64/mm/pageattr.c | 6 ++++++ 1 file changed, 6 insertions(+)