From: Kirill A. Shutemov Date: Mon, 3 Apr 2023 11:10:20 +0000 (+0300) Subject: x86/mm/iommu/sva: Do not allow to set FORCE_TAGGED_SVA bit from outside X-Git-Tag: v6.6.7~2964^2 X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=97740266de26e5dfe6e4fbecacb6995b66c2e378;p=platform%2Fkernel%2Flinux-starfive.git x86/mm/iommu/sva: Do not allow to set FORCE_TAGGED_SVA bit from outside arch_prctl(ARCH_FORCE_TAGGED_SVA) overrides the default and allows LAM and SVA to co-exist in the process. It is expected by called by the process when it knows what it is doing. arch_prctl() operates on the current process, but the same code is reachable from ptrace where it can be called on arbitrary task. Make it strict and only allow to set MM_CONTEXT_FORCE_TAGGED_SVA for the current process. Fixes: 23e5d9ec2bab ("x86/mm/iommu/sva: Make LAM and SVA mutually exclusive") Suggested-by: Dmitry Vyukov Signed-off-by: Kirill A. Shutemov Signed-off-by: Dave Hansen Reviewed-by: Dmitry Vyukov Link: https://lore.kernel.org/all/20230403111020.3136-3-kirill.shutemov%40linux.intel.com --- diff --git a/arch/x86/kernel/process_64.c b/arch/x86/kernel/process_64.c index bc2ac56..223b223 100644 --- a/arch/x86/kernel/process_64.c +++ b/arch/x86/kernel/process_64.c @@ -883,6 +883,8 @@ long do_arch_prctl_64(struct task_struct *task, int option, unsigned long arg2) case ARCH_ENABLE_TAGGED_ADDR: return prctl_enable_tagged_addr(task->mm, arg2); case ARCH_FORCE_TAGGED_SVA: + if (current != task) + return -EINVAL; set_bit(MM_CONTEXT_FORCE_TAGGED_SVA, &task->mm->context.flags); return 0; case ARCH_GET_MAX_TAG_BITS: