Commit 8d965444 authored by Eric Dumazet's avatar Eric Dumazet Committed by David S. Miller
Browse files

[FIB]: full_children & empty_children should be uint, not ushort 



If declared as unsigned short, these fields can overflow, and whole
trie logic is broken. I could not make the machine crash, but some
tnode can never be freed.

Note for 64 bit arches : By reordering t_key and parent in [node,
leaf, tnode] structures, we can use 32 bits hole after t_key so that
sizeof(struct tnode) doesnt change after this patch.

Signed-off-by: default avatarEric Dumazet <dada1@cosmosbay.com>
Signed-off-by: default avatarRobert Olsson <robert.olsson@its.uu.se>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent f16f3026

net/ipv4/fib_trie.c

+12 −13
Original line number Diff line number Diff line
@@ -97,13 +97,13 @@ typedef unsigned int t_key; 
#define IS_LEAF(n) (n->parent & T_LEAF)



struct node {

	t_key key;

	unsigned long parent;

	t_key key;

};



struct leaf {

	t_key key;

	unsigned long parent;

	t_key key;

	struct hlist_head list;

	struct rcu_head rcu;

};
@@ -116,12 +116,12 @@ struct leaf_info { 
};



struct tnode {

	t_key key;

	unsigned long parent;

	t_key key;

	unsigned char pos;		/* 2log(KEYLENGTH) bits needed */

	unsigned char bits;		/* 2log(KEYLENGTH) bits needed */

	unsigned short full_children;	/* KEYLENGTH bits needed */

	unsigned short empty_children;	/* KEYLENGTH bits needed */

	unsigned int full_children;	/* KEYLENGTH bits needed */

	unsigned int empty_children;	/* KEYLENGTH bits needed */

	struct rcu_head rcu;

	struct node *child[0];

};
@@ -329,12 +329,12 @@ static inline void free_leaf_info(struct leaf_info *leaf) 
	call_rcu(&leaf->rcu, __leaf_info_free_rcu);

}



static struct tnode *tnode_alloc(unsigned int size)

static struct tnode *tnode_alloc(size_t size)

{

	struct page *pages;



	if (size <= PAGE_SIZE)

		return kcalloc(size, 1, GFP_KERNEL);

		return kzalloc(size, GFP_KERNEL);



	pages = alloc_pages(GFP_KERNEL|__GFP_ZERO, get_order(size));

	if (!pages)
@@ -346,8 +346,8 @@ static struct tnode *tnode_alloc(unsigned int size) 
static void __tnode_free_rcu(struct rcu_head *head)

{

	struct tnode *tn = container_of(head, struct tnode, rcu);

	unsigned int size = sizeof(struct tnode) +

		(1 << tn->bits) * sizeof(struct node *);

	size_t size = sizeof(struct tnode) +

		      (sizeof(struct node *) << tn->bits);



	if (size <= PAGE_SIZE)

		kfree(tn);
@@ -386,8 +386,7 @@ static struct leaf_info *leaf_info_new(int plen) 


static struct tnode* tnode_new(t_key key, int pos, int bits)

{

	int nchildren = 1<<bits;

	int sz = sizeof(struct tnode) + nchildren * sizeof(struct node *);

	size_t sz = sizeof(struct tnode) + (sizeof(struct node *) << bits);

	struct tnode *tn = tnode_alloc(sz);



	if (tn) {
@@ -399,8 +398,8 @@ static struct tnode* tnode_new(t_key key, int pos, int bits) 
		tn->empty_children = 1<<bits;

	}



	pr_debug("AT %p s=%u %u\n", tn, (unsigned int) sizeof(struct tnode),

		 (unsigned int) (sizeof(struct node) * 1<<bits));

	pr_debug("AT %p s=%u %lu\n", tn, (unsigned int) sizeof(struct tnode),

		 (unsigned long) (sizeof(struct node) << bits));

	return tn;

}

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