The current rose_remove_neigh() performs two distinct operations: 1. Removes rose_neigh from rose_neigh_list 2. Frees the rose_neigh structure Split these operations into separate functions to improve maintainability and prepare for upcoming refcount_t conversion. The timer cleanup remains in rose_remove_neigh() because free operations can be called from timer itself. This patch introduce rose_neigh_put() to handle the freeing of rose_neigh structures and modify rose_remove_neigh() to handle removal only. Signed-off-by: Takamitsu Iwai --- include/net/rose.h | 8 ++++++++ net/rose/rose_route.c | 15 ++++++--------- 2 files changed, 14 insertions(+), 9 deletions(-) diff --git a/include/net/rose.h b/include/net/rose.h index 23267b4efcfa..174b4f605d84 100644 --- a/include/net/rose.h +++ b/include/net/rose.h @@ -151,6 +151,14 @@ struct rose_sock { #define rose_sk(sk) ((struct rose_sock *)(sk)) +static inline void rose_neigh_put(struct rose_neigh *rose_neigh) +{ + if (rose_neigh->ax25) + ax25_cb_put(rose_neigh->ax25); + kfree(rose_neigh->digipeat); + kfree(rose_neigh); +} + /* af_rose.c */ extern ax25_address rose_callsign; extern int sysctl_rose_restart_request_timeout; diff --git a/net/rose/rose_route.c b/net/rose/rose_route.c index b72bf8a08d48..0c44c416f485 100644 --- a/net/rose/rose_route.c +++ b/net/rose/rose_route.c @@ -234,20 +234,12 @@ static void rose_remove_neigh(struct rose_neigh *rose_neigh) if ((s = rose_neigh_list) == rose_neigh) { rose_neigh_list = rose_neigh->next; - if (rose_neigh->ax25) - ax25_cb_put(rose_neigh->ax25); - kfree(rose_neigh->digipeat); - kfree(rose_neigh); return; } while (s != NULL && s->next != NULL) { if (s->next == rose_neigh) { s->next = rose_neigh->next; - if (rose_neigh->ax25) - ax25_cb_put(rose_neigh->ax25); - kfree(rose_neigh->digipeat); - kfree(rose_neigh); return; } @@ -331,8 +323,10 @@ static int rose_del_node(struct rose_route_struct *rose_route, if (rose_node->neighbour[i] == rose_neigh) { rose_neigh->count--; - if (rose_neigh->count == 0 && rose_neigh->use == 0) + if (rose_neigh->count == 0 && rose_neigh->use == 0) { rose_remove_neigh(rose_neigh); + rose_neigh_put(rose_neigh); + } rose_node->count--; @@ -513,6 +507,7 @@ void rose_rt_device_down(struct net_device *dev) } rose_remove_neigh(s); + rose_neigh_put(s); } spin_unlock_bh(&rose_neigh_list_lock); spin_unlock_bh(&rose_node_list_lock); @@ -569,6 +564,7 @@ static int rose_clear_routes(void) if (s->use == 0 && !s->loopback) { s->count = 0; rose_remove_neigh(s); + rose_neigh_put(s); } } @@ -1301,6 +1297,7 @@ void __exit rose_rt_free(void) rose_neigh = rose_neigh->next; rose_remove_neigh(s); + rose_neigh_put(s); } while (rose_node != NULL) { -- 2.39.5 (Apple Git-154) The 'use' field in struct rose_neigh is used as a reference counter but lacks atomicity. This can lead to race conditions where a rose_neigh structure is freed while still being referenced by other code paths. For example, when rose_neigh->use becomes zero during an ioctl operation via rose_rt_ioctl(), the structure may be removed while its timer is still active, potentially causing use-after-free issues. This patch changes the type of 'use' from unsigned short to refcount_t and updates all code paths to use rose_neigh_hold() and rose_neigh_put() which operate reference counts atomically. Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2") Signed-off-by: Takamitsu Iwai --- include/net/rose.h | 18 +++++++++++++----- net/rose/af_rose.c | 10 ++++------ net/rose/rose_in.c | 12 ++++++------ net/rose/rose_route.c | 26 +++++++++++++------------- net/rose/rose_timer.c | 2 +- 5 files changed, 37 insertions(+), 31 deletions(-) diff --git a/include/net/rose.h b/include/net/rose.h index 174b4f605d84..2b5491bbf39a 100644 --- a/include/net/rose.h +++ b/include/net/rose.h @@ -8,6 +8,7 @@ #ifndef _ROSE_H #define _ROSE_H +#include #include #include #include @@ -96,7 +97,7 @@ struct rose_neigh { ax25_cb *ax25; struct net_device *dev; unsigned short count; - unsigned short use; + refcount_t use; unsigned int number; char restarted; char dce_mode; @@ -151,12 +152,19 @@ struct rose_sock { #define rose_sk(sk) ((struct rose_sock *)(sk)) +static inline void rose_neigh_hold(struct rose_neigh *rose_neigh) +{ + refcount_inc(&rose_neigh->use); +} + static inline void rose_neigh_put(struct rose_neigh *rose_neigh) { - if (rose_neigh->ax25) - ax25_cb_put(rose_neigh->ax25); - kfree(rose_neigh->digipeat); - kfree(rose_neigh); + if (refcount_dec_and_test(&rose_neigh->use)) { + if (rose_neigh->ax25) + ax25_cb_put(rose_neigh->ax25); + kfree(rose_neigh->digipeat); + kfree(rose_neigh); + } } /* af_rose.c */ diff --git a/net/rose/af_rose.c b/net/rose/af_rose.c index 4e72b636a46a..6d0846e2be30 100644 --- a/net/rose/af_rose.c +++ b/net/rose/af_rose.c @@ -170,7 +170,7 @@ void rose_kill_by_neigh(struct rose_neigh *neigh) if (rose->neighbour == neigh) { rose_disconnect(s, ENETUNREACH, ROSE_OUT_OF_ORDER, 0); - rose->neighbour->use--; + rose_neigh_put(rose->neighbour); rose->neighbour = NULL; } } @@ -212,7 +212,7 @@ static void rose_kill_by_device(struct net_device *dev) if (rose->device == dev) { rose_disconnect(sk, ENETUNREACH, ROSE_OUT_OF_ORDER, 0); if (rose->neighbour) - rose->neighbour->use--; + rose_neigh_put(rose->neighbour); netdev_put(rose->device, &rose->dev_tracker); rose->device = NULL; } @@ -655,7 +655,7 @@ static int rose_release(struct socket *sock) break; case ROSE_STATE_2: - rose->neighbour->use--; + rose_neigh_put(rose->neighbour); release_sock(sk); rose_disconnect(sk, 0, -1, -1); lock_sock(sk); @@ -874,8 +874,6 @@ static int rose_connect(struct socket *sock, struct sockaddr *uaddr, int addr_le rose->state = ROSE_STATE_1; - rose->neighbour->use++; - rose_write_internal(sk, ROSE_CALL_REQUEST); rose_start_heartbeat(sk); rose_start_t1timer(sk); @@ -1077,7 +1075,7 @@ int rose_rx_call_request(struct sk_buff *skb, struct net_device *dev, struct ros GFP_ATOMIC); make_rose->facilities = facilities; - make_rose->neighbour->use++; + rose_neigh_hold(make_rose->neighbour); if (rose_sk(sk)->defer) { make_rose->state = ROSE_STATE_5; diff --git a/net/rose/rose_in.c b/net/rose/rose_in.c index 3e99181e759f..0276b393f0e5 100644 --- a/net/rose/rose_in.c +++ b/net/rose/rose_in.c @@ -56,7 +56,7 @@ static int rose_state1_machine(struct sock *sk, struct sk_buff *skb, int framety case ROSE_CLEAR_REQUEST: rose_write_internal(sk, ROSE_CLEAR_CONFIRMATION); rose_disconnect(sk, ECONNREFUSED, skb->data[3], skb->data[4]); - rose->neighbour->use--; + rose_neigh_put(rose->neighbour); break; default: @@ -79,12 +79,12 @@ static int rose_state2_machine(struct sock *sk, struct sk_buff *skb, int framety case ROSE_CLEAR_REQUEST: rose_write_internal(sk, ROSE_CLEAR_CONFIRMATION); rose_disconnect(sk, 0, skb->data[3], skb->data[4]); - rose->neighbour->use--; + rose_neigh_put(rose->neighbour); break; case ROSE_CLEAR_CONFIRMATION: rose_disconnect(sk, 0, -1, -1); - rose->neighbour->use--; + rose_neigh_put(rose->neighbour); break; default: @@ -121,7 +121,7 @@ static int rose_state3_machine(struct sock *sk, struct sk_buff *skb, int framety case ROSE_CLEAR_REQUEST: rose_write_internal(sk, ROSE_CLEAR_CONFIRMATION); rose_disconnect(sk, 0, skb->data[3], skb->data[4]); - rose->neighbour->use--; + rose_neigh_put(rose->neighbour); break; case ROSE_RR: @@ -234,7 +234,7 @@ static int rose_state4_machine(struct sock *sk, struct sk_buff *skb, int framety case ROSE_CLEAR_REQUEST: rose_write_internal(sk, ROSE_CLEAR_CONFIRMATION); rose_disconnect(sk, 0, skb->data[3], skb->data[4]); - rose->neighbour->use--; + rose_neigh_put(rose->neighbour); break; default: @@ -254,7 +254,7 @@ static int rose_state5_machine(struct sock *sk, struct sk_buff *skb, int framety if (frametype == ROSE_CLEAR_REQUEST) { rose_write_internal(sk, ROSE_CLEAR_CONFIRMATION); rose_disconnect(sk, 0, skb->data[3], skb->data[4]); - rose_sk(sk)->neighbour->use--; + rose_neigh_put(rose_sk(sk)->neighbour); } return 0; diff --git a/net/rose/rose_route.c b/net/rose/rose_route.c index 0c44c416f485..a032543bbbc8 100644 --- a/net/rose/rose_route.c +++ b/net/rose/rose_route.c @@ -93,11 +93,11 @@ static int __must_check rose_add_node(struct rose_route_struct *rose_route, rose_neigh->ax25 = NULL; rose_neigh->dev = dev; rose_neigh->count = 0; - rose_neigh->use = 0; rose_neigh->dce_mode = 0; rose_neigh->loopback = 0; rose_neigh->number = rose_neigh_no++; rose_neigh->restarted = 0; + refcount_set(&rose_neigh->use, 1); skb_queue_head_init(&rose_neigh->queue); @@ -255,10 +255,10 @@ static void rose_remove_route(struct rose_route *rose_route) struct rose_route *s; if (rose_route->neigh1 != NULL) - rose_route->neigh1->use--; + rose_neigh_put(rose_route->neigh1); if (rose_route->neigh2 != NULL) - rose_route->neigh2->use--; + rose_neigh_put(rose_route->neigh2); if ((s = rose_route_list) == rose_route) { rose_route_list = rose_route->next; @@ -323,7 +323,7 @@ static int rose_del_node(struct rose_route_struct *rose_route, if (rose_node->neighbour[i] == rose_neigh) { rose_neigh->count--; - if (rose_neigh->count == 0 && rose_neigh->use == 0) { + if (rose_neigh->count == 0) { rose_remove_neigh(rose_neigh); rose_neigh_put(rose_neigh); } @@ -375,11 +375,11 @@ void rose_add_loopback_neigh(void) sn->ax25 = NULL; sn->dev = NULL; sn->count = 0; - sn->use = 0; sn->dce_mode = 1; sn->loopback = 1; sn->number = rose_neigh_no++; sn->restarted = 1; + refcount_set(&sn->use, 1); skb_queue_head_init(&sn->queue); @@ -561,8 +561,7 @@ static int rose_clear_routes(void) s = rose_neigh; rose_neigh = rose_neigh->next; - if (s->use == 0 && !s->loopback) { - s->count = 0; + if (!s->loopback) { rose_remove_neigh(s); rose_neigh_put(s); } @@ -680,6 +679,7 @@ struct rose_neigh *rose_get_neigh(rose_address *addr, unsigned char *cause, for (i = 0; i < node->count; i++) { if (node->neighbour[i]->restarted) { res = node->neighbour[i]; + rose_neigh_hold(node->neighbour[i]); goto out; } } @@ -780,13 +780,13 @@ static void rose_del_route_by_neigh(struct rose_neigh *rose_neigh) } if (rose_route->neigh1 == rose_neigh) { - rose_route->neigh1->use--; + rose_neigh_put(rose_route->neigh1); rose_route->neigh1 = NULL; rose_transmit_clear_request(rose_route->neigh2, rose_route->lci2, ROSE_OUT_OF_ORDER, 0); } if (rose_route->neigh2 == rose_neigh) { - rose_route->neigh2->use--; + rose_neigh_put(rose_route->neigh2); rose_route->neigh2 = NULL; rose_transmit_clear_request(rose_route->neigh1, rose_route->lci1, ROSE_OUT_OF_ORDER, 0); } @@ -915,7 +915,7 @@ int rose_route_frame(struct sk_buff *skb, ax25_cb *ax25) rose_clear_queues(sk); rose->cause = ROSE_NETWORK_CONGESTION; rose->diagnostic = 0; - rose->neighbour->use--; + rose_neigh_put(rose->neighbour); rose->neighbour = NULL; rose->lci = 0; rose->state = ROSE_STATE_0; @@ -1058,8 +1058,8 @@ int rose_route_frame(struct sk_buff *skb, ax25_cb *ax25) rose_route->lci2 = new_lci; rose_route->neigh2 = new_neigh; - rose_route->neigh1->use++; - rose_route->neigh2->use++; + rose_neigh_hold(rose_route->neigh1); + rose_neigh_hold(rose_route->neigh2); rose_route->next = rose_route_list; rose_route_list = rose_route; @@ -1186,7 +1186,7 @@ static int rose_neigh_show(struct seq_file *seq, void *v) (rose_neigh->loopback) ? "RSLOOP-0" : ax2asc(buf, &rose_neigh->callsign), rose_neigh->dev ? rose_neigh->dev->name : "???", rose_neigh->count, - rose_neigh->use, + refcount_read(&rose_neigh->use) - 1, (rose_neigh->dce_mode) ? "DCE" : "DTE", (rose_neigh->restarted) ? "yes" : "no", ax25_display_timer(&rose_neigh->t0timer) / HZ, diff --git a/net/rose/rose_timer.c b/net/rose/rose_timer.c index 020369c49587..bb60a1654d61 100644 --- a/net/rose/rose_timer.c +++ b/net/rose/rose_timer.c @@ -180,7 +180,7 @@ static void rose_timer_expiry(struct timer_list *t) break; case ROSE_STATE_2: /* T3 */ - rose->neighbour->use--; + rose_neigh_put(rose->neighbour); rose_disconnect(sk, ETIMEDOUT, -1, -1); break; -- 2.39.5 (Apple Git-154) Current implementation maintains two separate reference counting mechanisms: the 'count' field in struct rose_neigh tracks references from rose_node structures, while the 'use' field (now refcount_t) tracks references from rose_sock. This patch merges these two reference counting systems using 'use' field for proper reference management. Specifically, this patch adds incrementing and decrementing of rose_neigh->use when rose_neigh->count is incremented or decremented. This patch also modifies rose_rt_free(), rose_rt_device_down() and rose_clear_route() to properly release references to rose_neigh objects before freeing a rose_node through rose_remove_node(). These changes ensure rose_neigh structures are properly freed only when all references, including those from rose_node structures, are released. As a result, this resolves a slab-use-after-free issue reported by Syzbot. Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2") Reported-by: syzbot+942297eecf7d2d61d1f1@syzkaller.appspotmail.com Closes: https://syzkaller.appspot.com/bug?extid=942297eecf7d2d61d1f1 Signed-off-by: Takamitsu Iwai --- net/rose/rose_route.c | 18 ++++++++++++++++-- 1 file changed, 16 insertions(+), 2 deletions(-) diff --git a/net/rose/rose_route.c b/net/rose/rose_route.c index a032543bbbc8..20e772114a39 100644 --- a/net/rose/rose_route.c +++ b/net/rose/rose_route.c @@ -178,6 +178,7 @@ static int __must_check rose_add_node(struct rose_route_struct *rose_route, } } rose_neigh->count++; + rose_neigh_hold(rose_neigh); goto out; } @@ -187,6 +188,7 @@ static int __must_check rose_add_node(struct rose_route_struct *rose_route, rose_node->neighbour[rose_node->count] = rose_neigh; rose_node->count++; rose_neigh->count++; + rose_neigh_hold(rose_neigh); } out: @@ -322,6 +324,7 @@ static int rose_del_node(struct rose_route_struct *rose_route, for (i = 0; i < rose_node->count; i++) { if (rose_node->neighbour[i] == rose_neigh) { rose_neigh->count--; + rose_neigh_put(rose_neigh); if (rose_neigh->count == 0) { rose_remove_neigh(rose_neigh); @@ -430,6 +433,7 @@ int rose_add_loopback_node(const rose_address *address) rose_node_list = rose_node; rose_loopback_neigh->count++; + rose_neigh_hold(rose_loopback_neigh); out: spin_unlock_bh(&rose_node_list_lock); @@ -461,6 +465,7 @@ void rose_del_loopback_node(const rose_address *address) rose_remove_node(rose_node); rose_loopback_neigh->count--; + rose_neigh_put(rose_loopback_neigh); out: spin_unlock_bh(&rose_node_list_lock); @@ -500,6 +505,7 @@ void rose_rt_device_down(struct net_device *dev) memmove(&t->neighbour[i], &t->neighbour[i + 1], sizeof(t->neighbour[0]) * (t->count - i)); + rose_neigh_put(s); } if (t->count <= 0) @@ -543,6 +549,7 @@ static int rose_clear_routes(void) { struct rose_neigh *s, *rose_neigh; struct rose_node *t, *rose_node; + int i; spin_lock_bh(&rose_node_list_lock); spin_lock_bh(&rose_neigh_list_lock); @@ -553,8 +560,12 @@ static int rose_clear_routes(void) while (rose_node != NULL) { t = rose_node; rose_node = rose_node->next; - if (!t->loopback) + + if (!t->loopback) { + for (i = 0; i < rose_node->count; i++) + rose_neigh_put(t->neighbour[i]); rose_remove_node(t); + } } while (rose_neigh != NULL) { @@ -1186,7 +1197,7 @@ static int rose_neigh_show(struct seq_file *seq, void *v) (rose_neigh->loopback) ? "RSLOOP-0" : ax2asc(buf, &rose_neigh->callsign), rose_neigh->dev ? rose_neigh->dev->name : "???", rose_neigh->count, - refcount_read(&rose_neigh->use) - 1, + refcount_read(&rose_neigh->use) - rose_neigh->count - 1, (rose_neigh->dce_mode) ? "DCE" : "DTE", (rose_neigh->restarted) ? "yes" : "no", ax25_display_timer(&rose_neigh->t0timer) / HZ, @@ -1291,6 +1302,7 @@ void __exit rose_rt_free(void) struct rose_neigh *s, *rose_neigh = rose_neigh_list; struct rose_node *t, *rose_node = rose_node_list; struct rose_route *u, *rose_route = rose_route_list; + int i; while (rose_neigh != NULL) { s = rose_neigh; @@ -1304,6 +1316,8 @@ void __exit rose_rt_free(void) t = rose_node; rose_node = rose_node->next; + for (i = 0; i < t->count; i++) + rose_neigh_put(t->neighbour[i]); rose_remove_node(t); } -- 2.39.5 (Apple Git-154)