From 24cecc37746393432d994c0dbc251fb9ac7c5d72 Mon Sep 17 00:00:00 2001 From: Catalin Marinas Date: Mon, 6 Jan 2020 14:35:39 +0000 Subject: arm64: Revert support for execute-only user mappings 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: # 4.9.x- Acked-by: Will Deacon Signed-off-by: Catalin Marinas Signed-off-by: Linus Torvalds --- mm/mmap.c | 6 ------ 1 file changed, 6 deletions(-) (limited to 'mm/mmap.c') diff --git a/mm/mmap.c b/mm/mmap.c index 9c648524e4dc..71e4ffc83bcd 100644 --- a/mm/mmap.c +++ b/mm/mmap.c @@ -90,12 +90,6 @@ 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, -- cgit v1.2.3