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https://github.com/torvalds/linux
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d7c816733d
Right now, __list_add() code is repeated either in list.h or in list_debug.c, but the only differences between the two versions are the debug checks. This commit therefore extracts these debug checks into a separate __list_add_valid() function and consolidates __list_add(). Additionally this new __list_add_valid() function will stop list manipulations if a corruption is detected, instead of allowing for further corruption that may lead to even worse conditions. This is slight refactoring of the same hardening done in PaX and Grsecurity. Signed-off-by: Kees Cook <keescook@chromium.org> Acked-by: Steven Rostedt <rostedt@goodmis.org> Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Acked-by: Rik van Riel <riel@redhat.com>
99 lines
2.6 KiB
C
99 lines
2.6 KiB
C
/*
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* Copyright 2006, Red Hat, Inc., Dave Jones
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* Released under the General Public License (GPL).
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*
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* This file contains the linked list validation for DEBUG_LIST.
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*/
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#include <linux/export.h>
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#include <linux/list.h>
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#include <linux/bug.h>
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#include <linux/kernel.h>
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#include <linux/rculist.h>
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/*
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* Check that the data structures for the list manipulations are reasonably
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* valid. Failures here indicate memory corruption (and possibly an exploit
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* attempt).
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*/
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bool __list_add_valid(struct list_head *new, struct list_head *prev,
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struct list_head *next)
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{
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if (unlikely(next->prev != prev)) {
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WARN(1, "list_add corruption. next->prev should be prev (%p), but was %p. (next=%p).\n",
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prev, next->prev, next);
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return false;
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}
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if (unlikely(prev->next != next)) {
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WARN(1, "list_add corruption. prev->next should be next (%p), but was %p. (prev=%p).\n",
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next, prev->next, prev);
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return false;
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}
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if (unlikely(new == prev || new == next)) {
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WARN(1, "list_add double add: new=%p, prev=%p, next=%p.\n",
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new, prev, next);
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return false;
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}
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return true;
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}
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EXPORT_SYMBOL(__list_add_valid);
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void __list_del_entry(struct list_head *entry)
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{
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struct list_head *prev, *next;
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prev = entry->prev;
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next = entry->next;
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if (WARN(next == LIST_POISON1,
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"list_del corruption, %p->next is LIST_POISON1 (%p)\n",
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entry, LIST_POISON1) ||
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WARN(prev == LIST_POISON2,
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"list_del corruption, %p->prev is LIST_POISON2 (%p)\n",
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entry, LIST_POISON2) ||
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WARN(prev->next != entry,
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"list_del corruption. prev->next should be %p, "
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"but was %p\n", entry, prev->next) ||
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WARN(next->prev != entry,
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"list_del corruption. next->prev should be %p, "
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"but was %p\n", entry, next->prev))
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return;
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__list_del(prev, next);
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}
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EXPORT_SYMBOL(__list_del_entry);
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/**
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* list_del - deletes entry from list.
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* @entry: the element to delete from the list.
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* Note: list_empty on entry does not return true after this, the entry is
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* in an undefined state.
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*/
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void list_del(struct list_head *entry)
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{
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__list_del_entry(entry);
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entry->next = LIST_POISON1;
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entry->prev = LIST_POISON2;
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}
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EXPORT_SYMBOL(list_del);
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/*
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* RCU variants.
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*/
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void __list_add_rcu(struct list_head *new,
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struct list_head *prev, struct list_head *next)
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{
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WARN(next->prev != prev,
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"list_add_rcu corruption. next->prev should be prev (%p), but was %p. (next=%p).\n",
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prev, next->prev, next);
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WARN(prev->next != next,
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"list_add_rcu corruption. prev->next should be next (%p), but was %p. (prev=%p).\n",
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next, prev->next, prev);
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new->next = next;
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new->prev = prev;
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rcu_assign_pointer(list_next_rcu(prev), new);
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next->prev = new;
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}
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EXPORT_SYMBOL(__list_add_rcu);
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