diff options
| author | Catalin Marinas <catalin.marinas@arm.com> | 2020-01-06 14:35:39 +0000 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2020-01-09 10:17:56 +0100 |
| commit | d9c64efbe05e4cced2c1ffbf93b658eab5714f54 (patch) | |
| tree | 80df9ace7c0cfd5614db3100203a87bfc6732c91 /mm | |
| parent | 7650b4b1df091815bbbbb837d308dd4154684f8a (diff) | |
arm64: Revert support for execute-only user mappings
commit 24cecc37746393432d994c0dbc251fb9ac7c5d72 upstream.
The ARMv8 64-bit architecture supports execute-only user permissions by
clearing the PTE_USER and PTE_UXN bits, practically making it a mostly
privileged mapping but from which user running at EL0 can still execute.
The downside, however, is that the kernel at EL1 inadvertently reading
such mapping would not trip over the PAN (privileged access never)
protection.
Revert the relevant bits from commit cab15ce604e5 ("arm64: Introduce
execute-only page access permissions") so that PROT_EXEC implies
PROT_READ (and therefore PTE_USER) until the architecture gains proper
support for execute-only user mappings.
Fixes: cab15ce604e5 ("arm64: Introduce execute-only page access permissions")
Cc: <stable@vger.kernel.org> # 4.9.x-
Acked-by: Will Deacon <will@kernel.org>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'mm')
| -rw-r--r-- | mm/mmap.c | 6 |
1 files changed, 0 insertions, 6 deletions
diff --git a/mm/mmap.c b/mm/mmap.c index 59fd53b41c9c..8c6ed06983f9 100644 --- a/mm/mmap.c +++ b/mm/mmap.c @@ -89,12 +89,6 @@ static void unmap_region(struct mm_struct *mm, * MAP_PRIVATE r: (no) no r: (yes) yes r: (no) yes r: (no) yes * w: (no) no w: (no) no w: (copy) copy w: (no) no * x: (no) no x: (no) yes x: (no) yes x: (yes) yes - * - * On arm64, PROT_EXEC has the following behaviour for both MAP_SHARED and - * MAP_PRIVATE: - * r: (no) no - * w: (no) no - * x: (yes) yes */ pgprot_t protection_map[16] __ro_after_init = { __P000, __P001, __P010, __P011, __P100, __P101, __P110, __P111, |