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The entire point of printing the pointers in list_debug is to see if there's any useful information in them (eg poison values, ASCII, etc); obscuring them to see if they compare equal makes them much less useful. If an attacker can force this message to be printed, we've already lost. Link: http://lkml.kernel.org/r/20180401223237.GV13332@bombadil.infradead.org Signed-off-by: Matthew Wilcox <mawilcox@microsoft.com> Reviewed-by: Tobin C. Harding <me@tobin.cc> Reviewed-by: Andrew Morton <akpm@linux-foundation.org> Cc: Eric Biggers <ebiggers3@gmail.com> Cc: Kees Cook <keescook@chromium.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
62 lines
1.8 KiB
C
62 lines
1.8 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 (CHECK_DATA_CORRUPTION(next->prev != prev,
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"list_add corruption. next->prev should be prev (%px), but was %px. (next=%px).\n",
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prev, next->prev, next) ||
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CHECK_DATA_CORRUPTION(prev->next != next,
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"list_add corruption. prev->next should be next (%px), but was %px. (prev=%px).\n",
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next, prev->next, prev) ||
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CHECK_DATA_CORRUPTION(new == prev || new == next,
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"list_add double add: new=%px, prev=%px, next=%px.\n",
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new, prev, next))
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return false;
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return true;
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}
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EXPORT_SYMBOL(__list_add_valid);
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bool __list_del_entry_valid(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 (CHECK_DATA_CORRUPTION(next == LIST_POISON1,
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"list_del corruption, %px->next is LIST_POISON1 (%px)\n",
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entry, LIST_POISON1) ||
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CHECK_DATA_CORRUPTION(prev == LIST_POISON2,
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"list_del corruption, %px->prev is LIST_POISON2 (%px)\n",
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entry, LIST_POISON2) ||
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CHECK_DATA_CORRUPTION(prev->next != entry,
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"list_del corruption. prev->next should be %px, but was %px\n",
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entry, prev->next) ||
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CHECK_DATA_CORRUPTION(next->prev != entry,
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"list_del corruption. next->prev should be %px, but was %px\n",
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entry, next->prev))
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return false;
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return true;
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}
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EXPORT_SYMBOL(__list_del_entry_valid);
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