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Subject[PATCH V4 2/2] ptr_ring: try vmalloc() when kmalloc() fails
Date
This patch switch to use kvmalloc_array() for using a vmalloc()
fallback to help in case kmalloc() fails.

Reported-by: syzbot+e4d4f9ddd4295539735d@syzkaller.appspotmail.com
Fixes: 2e0ab8ca83c12 ("ptr_ring: array based FIFO for pointers")
Signed-off-by: Jason Wang <jasowang@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
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