[PATCH V4 2/2] ptr_ring: try vmalloc() when kmalloc() fails

[Jason Wang]

This patch switch to use kvmalloc_array() for using a vmalloc()
fallback to help in case kmalloc() fails.

Reported-by: syzbot+e4d4f9ddd42955397...@syzkaller.appspotmail.com
Fixes: 2e0ab8ca83c12 ("ptr_ring: array based FIFO for pointers")
Signed-off-by: Jason Wang <jasow...@redhat.com>
---
 include/linux/ptr_ring.h | 13 ++++++++-----
 1 file changed, 8 insertions(+), 5 deletions(-)

diff --git a/include/linux/ptr_ring.h b/include/linux/ptr_ring.h
index 6051a5f..b884b77 100644
--- a/include/linux/ptr_ring.h
+++ b/include/linux/ptr_ring.h
@@ -464,11 +464,14 @@ static inline int ptr_ring_consume_batched_bh(struct 
ptr_ring *r,
        __PTR_RING_PEEK_CALL_v; \
 })
 
+/* Not all gfp_t flags (besides GFP_KERNEL) are allowed. See
+ * documentation for vmalloc for which of them are legal.
+ */
 static inline void **__ptr_ring_init_queue_alloc(unsigned int size, gfp_t gfp)
 {
        if (size * sizeof(void *) > KMALLOC_MAX_SIZE)
                return NULL;
-       return kcalloc(size, sizeof(void *), gfp);
+       return kvmalloc_array(size, sizeof(void *), gfp | __GFP_ZERO);
 }
 
 static inline void __ptr_ring_set_size(struct ptr_ring *r, int size)
@@ -603,7 +606,7 @@ static inline int ptr_ring_resize(struct ptr_ring *r, int 
size, gfp_t gfp,
        spin_unlock(&(r)->producer_lock);
        spin_unlock_irqrestore(&(r)->consumer_lock, flags);
 
-       kfree(old);
+       kvfree(old);
 
        return 0;
 }
@@ -643,7 +646,7 @@ static inline int ptr_ring_resize_multiple(struct ptr_ring 
**rings,
        }
 
        for (i = 0; i < nrings; ++i)
-               kfree(queues[i]);
+               kvfree(queues[i]);
 
        kfree(queues);
 
@@ -651,7 +654,7 @@ static inline int ptr_ring_resize_multiple(struct ptr_ring 
**rings,
 
 nomem:
        while (--i >= 0)
-               kfree(queues[i]);
+               kvfree(queues[i]);
 
        kfree(queues);
 
@@ -666,7 +669,7 @@ static inline void ptr_ring_cleanup(struct ptr_ring *r, 
void (*destroy)(void *))
        if (destroy)
                while ((ptr = ptr_ring_consume(r)))
                        destroy(ptr);
-       kfree(r->queue);
+       kvfree(r->queue);
 }
 
 #endif /* _LINUX_PTR_RING_H  */
-- 
2.7.4