4.20-stable review patch. If anyone has any objections, please let me know.
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[ Upstream commit 9f51c05dc41a6d69423e3d03d18eb7ab22f9ec19 ]
The problem is that we call this with a spin lock held. The call tree is: pvcalls_front_accept() holds bedata->socket_lock. -> create_active() -> __get_free_pages() uses GFP_KERNEL
The create_active() function is only called from pvcalls_front_accept() with a spin_lock held, The allocation is not allowed to sleep and GFP_KERNEL is not sufficient.
This issue was detected by using the Coccinelle software.
v2: Add a function doing the allocations which is called outside the lock and passing the allocated data to create_active().
v3: Use the matching deallocators i.e., free_page() and free_pages(), respectively.
v4: It would be better to pre-populate map (struct sock_mapping), rather than introducing one more new struct.
v5: Since allocating the data outside of this call it should also be freed outside, when create_active() fails. Move kzalloc(sizeof(*map2), GFP_ATOMIC) outside spinlock and use GFP_KERNEL instead.
v6: Drop the superfluous calls.
Suggested-by: Juergen Gross jgross@suse.com Suggested-by: Boris Ostrovsky boris.ostrovsky@oracle.com Suggested-by: Stefano Stabellini sstabellini@kernel.org Signed-off-by: Wen Yang wen.yang99@zte.com.cn Acked-by: Stefano Stabellini sstabellini@kernel.org CC: Julia Lawall julia.lawall@lip6.fr CC: Boris Ostrovsky boris.ostrovsky@oracle.com CC: Juergen Gross jgross@suse.com CC: Stefano Stabellini sstabellini@kernel.org CC: xen-devel@lists.xenproject.org CC: linux-kernel@vger.kernel.org Signed-off-by: Boris Ostrovsky boris.ostrovsky@oracle.com Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/xen/pvcalls-front.c | 81 +++++++++++++++++++++++++++---------- 1 file changed, 59 insertions(+), 22 deletions(-)
diff --git a/drivers/xen/pvcalls-front.c b/drivers/xen/pvcalls-front.c index 01588582ae663..6357160d466ab 100644 --- a/drivers/xen/pvcalls-front.c +++ b/drivers/xen/pvcalls-front.c @@ -341,6 +341,39 @@ int pvcalls_front_socket(struct socket *sock) return ret; }
+static void free_active_ring(struct sock_mapping *map) +{ + free_pages((unsigned long)map->active.data.in, + map->active.ring->ring_order); + free_page((unsigned long)map->active.ring); +} + +static int alloc_active_ring(struct sock_mapping *map) +{ + void *bytes; + + map->active.ring = (struct pvcalls_data_intf *) + get_zeroed_page(GFP_KERNEL); + if (!map->active.ring) + goto out; + + map->active.ring->ring_order = PVCALLS_RING_ORDER; + bytes = (void *)__get_free_pages(GFP_KERNEL | __GFP_ZERO, + PVCALLS_RING_ORDER); + if (!bytes) + goto out; + + map->active.data.in = bytes; + map->active.data.out = bytes + + XEN_FLEX_RING_SIZE(PVCALLS_RING_ORDER); + + return 0; + +out: + free_active_ring(map); + return -ENOMEM; +} + static int create_active(struct sock_mapping *map, int *evtchn) { void *bytes; @@ -349,15 +382,7 @@ static int create_active(struct sock_mapping *map, int *evtchn) *evtchn = -1; init_waitqueue_head(&map->active.inflight_conn_req);
- map->active.ring = (struct pvcalls_data_intf *) - __get_free_page(GFP_KERNEL | __GFP_ZERO); - if (map->active.ring == NULL) - goto out_error; - map->active.ring->ring_order = PVCALLS_RING_ORDER; - bytes = (void *)__get_free_pages(GFP_KERNEL | __GFP_ZERO, - PVCALLS_RING_ORDER); - if (bytes == NULL) - goto out_error; + bytes = map->active.data.in; for (i = 0; i < (1 << PVCALLS_RING_ORDER); i++) map->active.ring->ref[i] = gnttab_grant_foreign_access( pvcalls_front_dev->otherend_id, @@ -367,10 +392,6 @@ static int create_active(struct sock_mapping *map, int *evtchn) pvcalls_front_dev->otherend_id, pfn_to_gfn(virt_to_pfn((void *)map->active.ring)), 0);
- map->active.data.in = bytes; - map->active.data.out = bytes + - XEN_FLEX_RING_SIZE(PVCALLS_RING_ORDER); - ret = xenbus_alloc_evtchn(pvcalls_front_dev, evtchn); if (ret) goto out_error; @@ -391,8 +412,6 @@ static int create_active(struct sock_mapping *map, int *evtchn) out_error: if (*evtchn >= 0) xenbus_free_evtchn(pvcalls_front_dev, *evtchn); - free_pages((unsigned long)map->active.data.in, PVCALLS_RING_ORDER); - free_page((unsigned long)map->active.ring); return ret; }
@@ -412,17 +431,24 @@ int pvcalls_front_connect(struct socket *sock, struct sockaddr *addr, return PTR_ERR(map);
bedata = dev_get_drvdata(&pvcalls_front_dev->dev); + ret = alloc_active_ring(map); + if (ret < 0) { + pvcalls_exit_sock(sock); + return ret; + }
spin_lock(&bedata->socket_lock); ret = get_request(bedata, &req_id); if (ret < 0) { spin_unlock(&bedata->socket_lock); + free_active_ring(map); pvcalls_exit_sock(sock); return ret; } ret = create_active(map, &evtchn); if (ret < 0) { spin_unlock(&bedata->socket_lock); + free_active_ring(map); pvcalls_exit_sock(sock); return ret; } @@ -784,25 +810,36 @@ int pvcalls_front_accept(struct socket *sock, struct socket *newsock, int flags) } }
- spin_lock(&bedata->socket_lock); - ret = get_request(bedata, &req_id); - if (ret < 0) { + map2 = kzalloc(sizeof(*map2), GFP_KERNEL); + if (map2 == NULL) { clear_bit(PVCALLS_FLAG_ACCEPT_INFLIGHT, (void *)&map->passive.flags); - spin_unlock(&bedata->socket_lock); + pvcalls_exit_sock(sock); + return -ENOMEM; + } + ret = alloc_active_ring(map2); + if (ret < 0) { + clear_bit(PVCALLS_FLAG_ACCEPT_INFLIGHT, + (void *)&map->passive.flags); + kfree(map2); pvcalls_exit_sock(sock); return ret; } - map2 = kzalloc(sizeof(*map2), GFP_ATOMIC); - if (map2 == NULL) { + spin_lock(&bedata->socket_lock); + ret = get_request(bedata, &req_id); + if (ret < 0) { clear_bit(PVCALLS_FLAG_ACCEPT_INFLIGHT, (void *)&map->passive.flags); spin_unlock(&bedata->socket_lock); + free_active_ring(map2); + kfree(map2); pvcalls_exit_sock(sock); - return -ENOMEM; + return ret; } + ret = create_active(map2, &evtchn); if (ret < 0) { + free_active_ring(map2); kfree(map2); clear_bit(PVCALLS_FLAG_ACCEPT_INFLIGHT, (void *)&map->passive.flags);