From d43c57a1713ef73f5c423efecaa061ec4e448287 Mon Sep 17 00:00:00 2001 From: "Chang S. Bae" Date: Thu, 21 Oct 2021 15:55:15 -0700 Subject: [PATCH] x86/fpu: Reset permission and fpstate on exec() BugLink: https://bugs.launchpad.net/bugs/1967750 On exec(), extended register states saved in the buffer is cleared. With dynamic features, each task carries variables besides the register states. The struct fpu has permission information and struct fpstate contains buffer size and feature masks. They are all dynamically updated with dynamic features. Reset the current task's entire FPU data before an exec() so that the new task starts with default permission and fpstate. Rename the register state reset function because the old naming confuses as it does not reset struct fpstate. Signed-off-by: Chang S. Bae Signed-off-by: Borislav Petkov Link: https://lkml.kernel.org/r/20211021225527.10184-12-chang.seok.bae@intel.com (cherry picked from commit e61d6310a0f80cb986fd2076d432760b3619fb6d) Acked-by: Dimitri John Ledkov Signed-off-by: Andrea Righi --- arch/x86/kernel/fpu/core.c | 7 ++++--- 1 file changed, 4 insertions(+), 3 deletions(-) diff --git a/arch/x86/kernel/fpu/core.c b/arch/x86/kernel/fpu/core.c index 1ff6b83094a1..3349068cef7d 100644 --- a/arch/x86/kernel/fpu/core.c +++ b/arch/x86/kernel/fpu/core.c @@ -544,7 +544,7 @@ static inline void restore_fpregs_from_init_fpstate(u64 features_mask) /* * Reset current->fpu memory state to the init values. */ -static void fpu_reset_fpstate(void) +static void fpu_reset_fpregs(void) { struct fpu *fpu = ¤t->thread.fpu; @@ -579,7 +579,7 @@ void fpu__clear_user_states(struct fpu *fpu) fpregs_lock(); if (!cpu_feature_enabled(X86_FEATURE_FPU)) { - fpu_reset_fpstate(); + fpu_reset_fpregs(); fpregs_unlock(); return; } @@ -609,7 +609,8 @@ void fpu__clear_user_states(struct fpu *fpu) void fpu_flush_thread(void) { - fpu_reset_fpstate(); + fpstate_reset(¤t->thread.fpu); + fpu_reset_fpregs(); } /* * Load FPU context before returning to userspace. -- 2.39.5