1 files changed, 0 insertions, 134 deletions
diff --git a/kernel/stackleak.c b/kernel/stackleak.c
deleted file mode 100644
index b193a59fc05b..000000000000
--- a/kernel/stackleak.c
+++ /dev/null
@@ -1,134 +0,0 @@
-// SPDX-License-Identifier: GPL-2.0
-/*
- * This code fills the used part of the kernel stack with a poison value
- * before returning to userspace. It's part of the STACKLEAK feature
- * ported from grsecurity/PaX.
- *
- * Author: Alexander Popov <alex.popov@linux.com>
- *
- * STACKLEAK reduces the information which kernel stack leak bugs can
- * reveal and blocks some uninitialized stack variable attacks.
- */
-
-#include <linux/stackleak.h>
-#include <linux/kprobes.h>
-
-#ifdef CONFIG_STACKLEAK_RUNTIME_DISABLE
-#include <linux/jump_label.h>
-#include <linux/sysctl.h>
-
-static DEFINE_STATIC_KEY_FALSE(stack_erasing_bypass);
-
-int stack_erasing_sysctl(struct ctl_table *table, int write,
-			void __user *buffer, size_t *lenp, loff_t *ppos)
-{
-	int ret = 0;
-	int state = !static_branch_unlikely(&stack_erasing_bypass);
-	int prev_state = state;
-
-	table->data = &state;
-	table->maxlen = sizeof(int);
-	ret = proc_dointvec_minmax(table, write, buffer, lenp, ppos);
-	state = !!state;
-	if (ret || !write || state == prev_state)
-		return ret;
-
-	if (state)
-		static_branch_disable(&stack_erasing_bypass);
-	else
-		static_branch_enable(&stack_erasing_bypass);
-
-	pr_warn("stackleak: kernel stack erasing is %s\n",
-					state ? "enabled" : "disabled");
-	return ret;
-}
-
-#define skip_erasing()	static_branch_unlikely(&stack_erasing_bypass)
-#else
-#define skip_erasing()	false
-#endif /* CONFIG_STACKLEAK_RUNTIME_DISABLE */
-
-asmlinkage void notrace stackleak_erase(void)
-{
-	/* It would be nice not to have 'kstack_ptr' and 'boundary' on stack */
-	unsigned long kstack_ptr = current->lowest_stack;
-	unsigned long boundary = (unsigned long)end_of_stack(current);
-	unsigned int poison_count = 0;
-	const unsigned int depth = STACKLEAK_SEARCH_DEPTH / sizeof(unsigned long);
-
-	if (skip_erasing())
-		return;
-
-	/* Check that 'lowest_stack' value is sane */
-	if (unlikely(kstack_ptr - boundary >= THREAD_SIZE))
-		kstack_ptr = boundary;
-
-	/* Search for the poison value in the kernel stack */
-	while (kstack_ptr > boundary && poison_count <= depth) {
-		if (*(unsigned long *)kstack_ptr == STACKLEAK_POISON)
-			poison_count++;
-		else
-			poison_count = 0;
-
-		kstack_ptr -= sizeof(unsigned long);
-	}
-
-	/*
-	 * One 'long int' at the bottom of the thread stack is reserved and
-	 * should not be poisoned (see CONFIG_SCHED_STACK_END_CHECK=y).
-	 */
-	if (kstack_ptr == boundary)
-		kstack_ptr += sizeof(unsigned long);
-
-#ifdef CONFIG_STACKLEAK_METRICS
-	current->prev_lowest_stack = kstack_ptr;
-#endif
-
-	/*
-	 * Now write the poison value to the kernel stack. Start from
-	 * 'kstack_ptr' and move up till the new 'boundary'. We assume that
-	 * the stack pointer doesn't change when we write poison.
-	 */
-	if (on_thread_stack())
-		boundary = current_stack_pointer;
-	else
-		boundary = current_top_of_stack();
-
-	while (kstack_ptr < boundary) {
-		*(unsigned long *)kstack_ptr = STACKLEAK_POISON;
-		kstack_ptr += sizeof(unsigned long);
-	}
-
-	/* Reset the 'lowest_stack' value for the next syscall */
-	current->lowest_stack = current_top_of_stack() - THREAD_SIZE/64;
-}
-NOKPROBE_SYMBOL(stackleak_erase);
-
-void __used notrace stackleak_track_stack(void)
-{
-	/*
-	 * N.B. stackleak_erase() fills the kernel stack with the poison value,
-	 * which has the register width. That code assumes that the value
-	 * of 'lowest_stack' is aligned on the register width boundary.
-	 *
-	 * That is true for x86 and x86_64 because of the kernel stack
-	 * alignment on these platforms (for details, see 'cc_stack_align' in
-	 * arch/x86/Makefile). Take care of that when you port STACKLEAK to
-	 * new platforms.
-	 */
-	unsigned long sp = (unsigned long)&sp;
-
-	/*
-	 * Having CONFIG_STACKLEAK_TRACK_MIN_SIZE larger than
-	 * STACKLEAK_SEARCH_DEPTH makes the poison search in
-	 * stackleak_erase() unreliable. Let's prevent that.
-	 */
-	BUILD_BUG_ON(CONFIG_STACKLEAK_TRACK_MIN_SIZE > STACKLEAK_SEARCH_DEPTH);
-
-	if (sp < current->lowest_stack &&
-	    sp >= (unsigned long)task_stack_page(current) +
-						sizeof(unsigned long)) {
-		current->lowest_stack = sp;
-	}
-}
-EXPORT_SYMBOL(stackleak_track_stack);