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path: root/drivers/xen/pvcalls-front.c
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Diffstat (limited to 'drivers/xen/pvcalls-front.c')
-rw-r--r--drivers/xen/pvcalls-front.c88
1 files changed, 76 insertions, 12 deletions
diff --git a/drivers/xen/pvcalls-front.c b/drivers/xen/pvcalls-front.c
index 50ce4820f7ee..3e7aa807c317 100644
--- a/drivers/xen/pvcalls-front.c
+++ b/drivers/xen/pvcalls-front.c
@@ -32,6 +32,7 @@ struct pvcalls_bedata {
struct xen_pvcalls_front_ring ring;
grant_ref_t ref;
int irq;
+ bool disabled;
struct list_head socket_mappings;
spinlock_t socket_lock;
@@ -131,6 +132,20 @@ static inline int get_request(struct pvcalls_bedata *bedata, int *req_id)
return 0;
}
+/*
+ * Wait for the backend's response to req_id, or for the frontend to be
+ * disabled because the backend violated the wire protocol. Returns 0 once
+ * the response has arrived, or -EIO if the frontend was disabled.
+ */
+static int pvcalls_front_wait_rsp(struct pvcalls_bedata *bedata, u32 req_id)
+{
+ wait_event(bedata->inflight_req,
+ READ_ONCE(bedata->rsp[req_id].req_id) == req_id ||
+ READ_ONCE(bedata->disabled));
+
+ return READ_ONCE(bedata->disabled) ? -EIO : 0;
+}
+
static bool pvcalls_front_write_todo(struct sock_mapping *map)
{
struct pvcalls_data_intf *intf = map->active.ring;
@@ -168,7 +183,8 @@ static irqreturn_t pvcalls_front_event_handler(int irq, void *dev_id)
struct pvcalls_bedata *bedata;
struct xen_pvcalls_response *rsp;
uint8_t *src, *dst;
- int req_id = 0, more = 0, done = 0;
+ u32 req_id = 0;
+ int more = 0, done = 0;
if (dev == NULL)
return IRQ_HANDLED;
@@ -179,12 +195,31 @@ static irqreturn_t pvcalls_front_event_handler(int irq, void *dev_id)
pvcalls_exit();
return IRQ_HANDLED;
}
+ if (READ_ONCE(bedata->disabled)) {
+ pvcalls_exit();
+ return IRQ_HANDLED;
+ }
again:
while (RING_HAS_UNCONSUMED_RESPONSES(&bedata->ring)) {
rsp = RING_GET_RESPONSE(&bedata->ring, bedata->ring.rsp_cons);
req_id = rsp->req_id;
+ if (req_id >= PVCALLS_NR_RSP_PER_RING) {
+ /*
+ * The backend supplied a req_id that would index
+ * bedata->rsp[] out of bounds: a protocol violation
+ * from a malicious or buggy backend. Log once, stop
+ * trusting this backend and disable the frontend rather
+ * than silently dropping the response and continuing.
+ */
+ pr_err_once("pvcalls: backend sent out-of-range req_id %u, disabling frontend\n",
+ req_id);
+ WRITE_ONCE(bedata->disabled, true);
+ bedata->ring.rsp_cons++;
+ done = 1;
+ break;
+ }
if (rsp->cmd == PVCALLS_POLL) {
struct sock_mapping *map = (struct sock_mapping *)(uintptr_t)
rsp->u.poll.id;
@@ -217,7 +252,7 @@ again:
}
RING_FINAL_CHECK_FOR_RESPONSES(&bedata->ring, more);
- if (more)
+ if (more && !READ_ONCE(bedata->disabled))
goto again;
if (done)
wake_up(&bedata->inflight_req);
@@ -330,8 +365,11 @@ int pvcalls_front_socket(struct socket *sock)
if (notify)
notify_remote_via_irq(bedata->irq);
- wait_event(bedata->inflight_req,
- READ_ONCE(bedata->rsp[req_id].req_id) == req_id);
+ ret = pvcalls_front_wait_rsp(bedata, req_id);
+ if (ret) {
+ pvcalls_exit();
+ return ret;
+ }
/* read req_id, then the content */
smp_rmb();
@@ -477,8 +515,11 @@ int pvcalls_front_connect(struct socket *sock, struct sockaddr *addr,
if (notify)
notify_remote_via_irq(bedata->irq);
- wait_event(bedata->inflight_req,
- READ_ONCE(bedata->rsp[req_id].req_id) == req_id);
+ ret = pvcalls_front_wait_rsp(bedata, req_id);
+ if (ret) {
+ pvcalls_exit_sock(sock);
+ return ret;
+ }
/* read req_id, then the content */
smp_rmb();
@@ -711,8 +752,11 @@ int pvcalls_front_bind(struct socket *sock, struct sockaddr *addr, int addr_len)
if (notify)
notify_remote_via_irq(bedata->irq);
- wait_event(bedata->inflight_req,
- READ_ONCE(bedata->rsp[req_id].req_id) == req_id);
+ ret = pvcalls_front_wait_rsp(bedata, req_id);
+ if (ret) {
+ pvcalls_exit_sock(sock);
+ return ret;
+ }
/* read req_id, then the content */
smp_rmb();
@@ -761,8 +805,11 @@ int pvcalls_front_listen(struct socket *sock, int backlog)
if (notify)
notify_remote_via_irq(bedata->irq);
- wait_event(bedata->inflight_req,
- READ_ONCE(bedata->rsp[req_id].req_id) == req_id);
+ ret = pvcalls_front_wait_rsp(bedata, req_id);
+ if (ret) {
+ pvcalls_exit_sock(sock);
+ return ret;
+ }
/* read req_id, then the content */
smp_rmb();
@@ -820,6 +867,14 @@ int pvcalls_front_accept(struct socket *sock, struct socket *newsock,
}
}
+ if (READ_ONCE(bedata->disabled)) {
+ clear_bit(PVCALLS_FLAG_ACCEPT_INFLIGHT,
+ (void *)&map->passive.flags);
+ wake_up(&map->passive.inflight_accept_req);
+ pvcalls_exit_sock(sock);
+ return -EIO;
+ }
+
map2 = kzalloc_obj(*map2);
if (map2 == NULL) {
clear_bit(PVCALLS_FLAG_ACCEPT_INFLIGHT,
@@ -880,10 +935,18 @@ int pvcalls_front_accept(struct socket *sock, struct socket *newsock,
}
if (wait_event_interruptible(bedata->inflight_req,
- READ_ONCE(bedata->rsp[req_id].req_id) == req_id)) {
+ READ_ONCE(bedata->rsp[req_id].req_id) == req_id ||
+ READ_ONCE(bedata->disabled))) {
pvcalls_exit_sock(sock);
return -EINTR;
}
+ if (READ_ONCE(bedata->disabled)) {
+ clear_bit(PVCALLS_FLAG_ACCEPT_INFLIGHT,
+ (void *)&map->passive.flags);
+ wake_up(&map->passive.inflight_accept_req);
+ pvcalls_exit_sock(sock);
+ return -EIO;
+ }
/* read req_id, then the content */
smp_rmb();
@@ -1054,7 +1117,8 @@ int pvcalls_front_release(struct socket *sock)
notify_remote_via_irq(bedata->irq);
wait_event(bedata->inflight_req,
- READ_ONCE(bedata->rsp[req_id].req_id) == req_id);
+ READ_ONCE(bedata->rsp[req_id].req_id) == req_id ||
+ READ_ONCE(bedata->disabled));
if (map->active_socket) {
/*
generated by cgit v1.2.3 (git 2.39.1) at 2026-07-07 03:30:34 +0000