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authorLinus Torvalds <torvalds@linux-foundation.org>2021-06-20 09:09:58 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2021-06-20 09:09:58 -0700
commit8363e795eb79a74c857ba89e3b04668a33fe3344 (patch)
treeedfdbfa3be22e945ce84260d2a48b7fb6cdac210 /arch/x86/kernel/fpu/signal.c
parentb84a7c286cecf0604a5f8bd5dfcd5e1ca7233e15 (diff)
parent28e5e44aa3f4e0e0370864ed008fb5e2d85f4dc8 (diff)
Merge tag 'x86_urgent_for_v5.13_rc6' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull x86 fixes from Borislav Petkov: "A first set of urgent fixes to the FPU/XSTATE handling mess^W code. (There's a lot more in the pipe): - Prevent corruption of the XSTATE buffer in signal handling by validating what is being copied from userspace first. - Invalidate other task's preserved FPU registers on XRSTOR failure (#PF) because latter can still modify some of them. - Restore the proper PKRU value in case userspace modified it - Reset FPU state when signal restoring fails Other: - Map EFI boot services data memory as encrypted in a SEV guest so that the guest can access it and actually boot properly - Two SGX correctness fixes: proper resources freeing and a NUMA fix" * tag 'x86_urgent_for_v5.13_rc6' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: x86/mm: Avoid truncating memblocks for SGX memory x86/sgx: Add missing xa_destroy() when virtual EPC is destroyed x86/fpu: Reset state for all signal restore failures x86/pkru: Write hardware init value to PKRU when xstate is init x86/process: Check PF_KTHREAD and not current->mm for kernel threads x86/fpu: Invalidate FPU state after a failed XRSTOR from a user buffer x86/fpu: Prevent state corruption in __fpu__restore_sig() x86/ioremap: Map EFI-reserved memory as encrypted for SEV
Diffstat (limited to 'arch/x86/kernel/fpu/signal.c')
-rw-r--r--arch/x86/kernel/fpu/signal.c54
1 files changed, 35 insertions, 19 deletions
diff --git a/arch/x86/kernel/fpu/signal.c b/arch/x86/kernel/fpu/signal.c
index a4ec65317a7f..ec3ae3054792 100644
--- a/arch/x86/kernel/fpu/signal.c
+++ b/arch/x86/kernel/fpu/signal.c
@@ -307,13 +307,17 @@ static int __fpu__restore_sig(void __user *buf, void __user *buf_fx, int size)
return 0;
}
- if (!access_ok(buf, size))
- return -EACCES;
+ if (!access_ok(buf, size)) {
+ ret = -EACCES;
+ goto out;
+ }
- if (!static_cpu_has(X86_FEATURE_FPU))
- return fpregs_soft_set(current, NULL,
- 0, sizeof(struct user_i387_ia32_struct),
- NULL, buf) != 0;
+ if (!static_cpu_has(X86_FEATURE_FPU)) {
+ ret = fpregs_soft_set(current, NULL, 0,
+ sizeof(struct user_i387_ia32_struct),
+ NULL, buf);
+ goto out;
+ }
if (use_xsave()) {
struct _fpx_sw_bytes fx_sw_user;
@@ -369,6 +373,25 @@ static int __fpu__restore_sig(void __user *buf, void __user *buf_fx, int size)
fpregs_unlock();
return 0;
}
+
+ /*
+ * The above did an FPU restore operation, restricted to
+ * the user portion of the registers, and failed, but the
+ * microcode might have modified the FPU registers
+ * nevertheless.
+ *
+ * If the FPU registers do not belong to current, then
+ * invalidate the FPU register state otherwise the task might
+ * preempt current and return to user space with corrupted
+ * FPU registers.
+ *
+ * In case current owns the FPU registers then no further
+ * action is required. The fixup below will handle it
+ * correctly.
+ */
+ if (test_thread_flag(TIF_NEED_FPU_LOAD))
+ __cpu_invalidate_fpregs_state();
+
fpregs_unlock();
} else {
/*
@@ -377,7 +400,7 @@ static int __fpu__restore_sig(void __user *buf, void __user *buf_fx, int size)
*/
ret = __copy_from_user(&env, buf, sizeof(env));
if (ret)
- goto err_out;
+ goto out;
envp = &env;
}
@@ -405,16 +428,9 @@ static int __fpu__restore_sig(void __user *buf, void __user *buf_fx, int size)
if (use_xsave() && !fx_only) {
u64 init_bv = xfeatures_mask_user() & ~user_xfeatures;
- if (using_compacted_format()) {
- ret = copy_user_to_xstate(&fpu->state.xsave, buf_fx);
- } else {
- ret = __copy_from_user(&fpu->state.xsave, buf_fx, state_size);
-
- if (!ret && state_size > offsetof(struct xregs_state, header))
- ret = validate_user_xstate_header(&fpu->state.xsave.header);
- }
+ ret = copy_user_to_xstate(&fpu->state.xsave, buf_fx);
if (ret)
- goto err_out;
+ goto out;
sanitize_restored_user_xstate(&fpu->state, envp, user_xfeatures,
fx_only);
@@ -434,7 +450,7 @@ static int __fpu__restore_sig(void __user *buf, void __user *buf_fx, int size)
ret = __copy_from_user(&fpu->state.fxsave, buf_fx, state_size);
if (ret) {
ret = -EFAULT;
- goto err_out;
+ goto out;
}
sanitize_restored_user_xstate(&fpu->state, envp, user_xfeatures,
@@ -452,7 +468,7 @@ static int __fpu__restore_sig(void __user *buf, void __user *buf_fx, int size)
} else {
ret = __copy_from_user(&fpu->state.fsave, buf_fx, state_size);
if (ret)
- goto err_out;
+ goto out;
fpregs_lock();
ret = copy_kernel_to_fregs_err(&fpu->state.fsave);
@@ -463,7 +479,7 @@ static int __fpu__restore_sig(void __user *buf, void __user *buf_fx, int size)
fpregs_deactivate(fpu);
fpregs_unlock();
-err_out:
+out:
if (ret)
fpu__clear_user_states(fpu);
return ret;