4.19-stable review patch. If anyone has any objections, please let me know.
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[ Upstream commit b4711098066f1cf808d4dc11a1a842860a3292fe ]
static checker warning: drivers/xen/pvcalls-front.c:373 alloc_active_ring() error: we previously assumed 'map->active.ring' could be null (see line 357)
drivers/xen/pvcalls-front.c 351 static int alloc_active_ring(struct sock_mapping *map) 352 { 353 void *bytes; 354 355 map->active.ring = (struct pvcalls_data_intf *) 356 get_zeroed_page(GFP_KERNEL); 357 if (!map->active.ring) ^^^^^^^^^^^^^^^^^ Check
358 goto out; 359 360 map->active.ring->ring_order = PVCALLS_RING_ORDER; 361 bytes = (void *)__get_free_pages(GFP_KERNEL | __GFP_ZERO, 362 PVCALLS_RING_ORDER); 363 if (!bytes) 364 goto out; 365 366 map->active.data.in = bytes; 367 map->active.data.out = bytes + 368 XEN_FLEX_RING_SIZE(PVCALLS_RING_ORDER); 369 370 return 0; 371 372 out: --> 373 free_active_ring(map); ^^^ Add null check on map->active.ring before dereferencing it to avoid any NULL pointer dereferences.
Fixes: 9f51c05dc41a ("pvcalls-front: Avoid get_free_pages(GFP_KERNEL) under spinlock") Reported-by: Dan Carpenter dan.carpenter@oracle.com Suggested-by: Boris Ostrovsky boris.ostrovsky@oracle.com Signed-off-by: Wen Yang wen.yang99@zte.com.cn Reviewed-by: Boris Ostrovsky boris.ostrovsky@oracle.com CC: Boris Ostrovsky boris.ostrovsky@oracle.com CC: Juergen Gross jgross@suse.com CC: Stefano Stabellini sstabellini@kernel.org CC: Dan Carpenter dan.carpenter@oracle.com 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 | 3 +++ 1 file changed, 3 insertions(+)
diff --git a/drivers/xen/pvcalls-front.c b/drivers/xen/pvcalls-front.c index 6357160d466ab..91da7e44d5d4f 100644 --- a/drivers/xen/pvcalls-front.c +++ b/drivers/xen/pvcalls-front.c @@ -343,6 +343,9 @@ int pvcalls_front_socket(struct socket *sock)
static void free_active_ring(struct sock_mapping *map) { + if (!map->active.ring) + return; + free_pages((unsigned long)map->active.data.in, map->active.ring->ring_order); free_page((unsigned long)map->active.ring);