From 36c4a73bf8d24721222d9ee4080ac955973fd388 Mon Sep 17 00:00:00 2001 From: Andrey Konovalov Date: Thu, 24 Mar 2022 18:11:38 -0700 Subject: kasan, arm64: don't tag executable vmalloc allocations Besides asking vmalloc memory to be executable via the prot argument of __vmalloc_node_range() (see the previous patch), the kernel can skip that bit and instead mark memory as executable via set_memory_x(). Once tag-based KASAN modes start tagging vmalloc allocations, executing code from such allocations will lead to the PC register getting a tag, which is not tolerated by the kernel. Generic kernel code typically allocates memory via module_alloc() if it intends to mark memory as executable. (On arm64 module_alloc() uses __vmalloc_node_range() without setting the executable bit). Thus, reset pointer tags of pointers returned from module_alloc(). However, on arm64 there's an exception: the eBPF subsystem. Instead of using module_alloc(), it uses vmalloc() (via bpf_jit_alloc_exec()) to allocate its JIT region. Thus, reset pointer tags of pointers returned from bpf_jit_alloc_exec(). Resetting tags for these pointers results in untagged pointers being passed to set_memory_x(). This causes conflicts in arithmetic checks in change_memory_common(), as vm_struct->addr pointer returned by find_vm_area() is tagged. Reset pointer tag of find_vm_area(addr)->addr in change_memory_common(). Link: https://lkml.kernel.org/r/b7b2595423340cd7d76b770e5d519acf3b72f0ab.1643047180.git.andreyknvl@google.com Signed-off-by: Andrey Konovalov Acked-by: Catalin Marinas Acked-by: Marco Elver Cc: Alexander Potapenko Cc: Andrey Ryabinin Cc: Dmitry Vyukov Cc: Evgenii Stepanov Cc: Mark Rutland Cc: Peter Collingbourne Cc: Vincenzo Frascino Cc: Will Deacon Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- arch/arm64/kernel/module.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) (limited to 'arch/arm64/kernel') diff --git a/arch/arm64/kernel/module.c b/arch/arm64/kernel/module.c index d3a1fa818348..f2d4bb14bfab 100644 --- a/arch/arm64/kernel/module.c +++ b/arch/arm64/kernel/module.c @@ -63,7 +63,8 @@ void *module_alloc(unsigned long size) return NULL; } - return p; + /* Memory is intended to be executable, reset the pointer tag. */ + return kasan_reset_tag(p); } enum aarch64_reloc_op { -- cgit