Commit c3873070 authored by Florian Westphal's avatar Florian Westphal

netfilter: nf_queue: fix possible use-after-free

Eric Dumazet says:
  The sock_hold() side seems suspect, because there is no guarantee
  that sk_refcnt is not already 0.

On failure, we cannot queue the packet and need to indicate an
error.  The packet will be dropped by the caller.

v2: split skb prefetch hunk into separate change

Fixes: 271b72c7 ("udp: RCU handling for Unicast packets.")
Reported-by: default avatarEric Dumazet <eric.dumazet@gmail.com>
Reviewed-by: default avatarEric Dumazet <edumazet@google.com>
Signed-off-by: default avatarFlorian Westphal <fw@strlen.de>
parent 2e78855d
...@@ -37,7 +37,7 @@ void nf_register_queue_handler(const struct nf_queue_handler *qh); ...@@ -37,7 +37,7 @@ void nf_register_queue_handler(const struct nf_queue_handler *qh);
void nf_unregister_queue_handler(void); void nf_unregister_queue_handler(void);
void nf_reinject(struct nf_queue_entry *entry, unsigned int verdict); void nf_reinject(struct nf_queue_entry *entry, unsigned int verdict);
void nf_queue_entry_get_refs(struct nf_queue_entry *entry); bool nf_queue_entry_get_refs(struct nf_queue_entry *entry);
void nf_queue_entry_free(struct nf_queue_entry *entry); void nf_queue_entry_free(struct nf_queue_entry *entry);
static inline void init_hashrandom(u32 *jhash_initval) static inline void init_hashrandom(u32 *jhash_initval)
......
...@@ -96,19 +96,21 @@ static void __nf_queue_entry_init_physdevs(struct nf_queue_entry *entry) ...@@ -96,19 +96,21 @@ static void __nf_queue_entry_init_physdevs(struct nf_queue_entry *entry)
} }
/* Bump dev refs so they don't vanish while packet is out */ /* Bump dev refs so they don't vanish while packet is out */
void nf_queue_entry_get_refs(struct nf_queue_entry *entry) bool nf_queue_entry_get_refs(struct nf_queue_entry *entry)
{ {
struct nf_hook_state *state = &entry->state; struct nf_hook_state *state = &entry->state;
if (state->sk && !refcount_inc_not_zero(&state->sk->sk_refcnt))
return false;
dev_hold(state->in); dev_hold(state->in);
dev_hold(state->out); dev_hold(state->out);
if (state->sk)
sock_hold(state->sk);
#if IS_ENABLED(CONFIG_BRIDGE_NETFILTER) #if IS_ENABLED(CONFIG_BRIDGE_NETFILTER)
dev_hold(entry->physin); dev_hold(entry->physin);
dev_hold(entry->physout); dev_hold(entry->physout);
#endif #endif
return true;
} }
EXPORT_SYMBOL_GPL(nf_queue_entry_get_refs); EXPORT_SYMBOL_GPL(nf_queue_entry_get_refs);
...@@ -196,7 +198,10 @@ static int __nf_queue(struct sk_buff *skb, const struct nf_hook_state *state, ...@@ -196,7 +198,10 @@ static int __nf_queue(struct sk_buff *skb, const struct nf_hook_state *state,
__nf_queue_entry_init_physdevs(entry); __nf_queue_entry_init_physdevs(entry);
nf_queue_entry_get_refs(entry); if (!nf_queue_entry_get_refs(entry)) {
kfree(entry);
return -ENOTCONN;
}
switch (entry->state.pf) { switch (entry->state.pf) {
case AF_INET: case AF_INET:
......
...@@ -710,9 +710,15 @@ static struct nf_queue_entry * ...@@ -710,9 +710,15 @@ static struct nf_queue_entry *
nf_queue_entry_dup(struct nf_queue_entry *e) nf_queue_entry_dup(struct nf_queue_entry *e)
{ {
struct nf_queue_entry *entry = kmemdup(e, e->size, GFP_ATOMIC); struct nf_queue_entry *entry = kmemdup(e, e->size, GFP_ATOMIC);
if (entry)
nf_queue_entry_get_refs(entry); if (!entry)
return entry; return NULL;
if (nf_queue_entry_get_refs(entry))
return entry;
kfree(entry);
return NULL;
} }
#if IS_ENABLED(CONFIG_BRIDGE_NETFILTER) #if IS_ENABLED(CONFIG_BRIDGE_NETFILTER)
......
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