refcount_t type and corresponding API should be
used instead of atomic_t when the variable is used as
a reference counter. This allows to avoid accidental
refcounter overflows that might lead to use-after-free
situations.
Signed-off-by: Elena Reshetova <elena.reshetova@xxxxxxxxx>
Signed-off-by: Hans Liljestrand <ishkamiel@xxxxxxxxx>
Signed-off-by: Kees Cook <keescook@xxxxxxxxxxxx>
Signed-off-by: David Windsor <dwindsor@xxxxxxxxx>
---
include/linux/skbuff.h | 4 ++--
net/core/skbuff.c | 10 +++++-----
2 files changed, 7 insertions(+), 7 deletions(-)
diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h
index 0bcaec4..63ce21f 100644
--- a/include/linux/skbuff.h
+++ b/include/linux/skbuff.h
@@ -945,7 +945,7 @@ struct sk_buff_fclones {
struct sk_buff skb2;
- atomic_t fclone_ref;
+ refcount_t fclone_ref;
};
/**
@@ -965,7 +965,7 @@ static inline bool skb_fclone_busy(const struct sock *sk,
fclones = container_of(skb, struct sk_buff_fclones, skb1);
return skb->fclone == SKB_FCLONE_ORIG &&
- atomic_read(&fclones->fclone_ref) > 1 &&
+ refcount_read(&fclones->fclone_ref) > 1 &&
fclones->skb2.sk == sk;
}
diff --git a/net/core/skbuff.c b/net/core/skbuff.c
index 94e961f..6911269 100644
--- a/net/core/skbuff.c
+++ b/net/core/skbuff.c
@@ -268,7 +268,7 @@ struct sk_buff *__alloc_skb(unsigned int size, gfp_t gfp_mask,
kmemcheck_annotate_bitfield(&fclones->skb2, flags1);
skb->fclone = SKB_FCLONE_ORIG;
- atomic_set(&fclones->fclone_ref, 1);
+ refcount_set(&fclones->fclone_ref, 1);
fclones->skb2.fclone = SKB_FCLONE_CLONE;
}
@@ -629,7 +629,7 @@ static void kfree_skbmem(struct sk_buff *skb)
* This test would have no chance to be true for the clone,
* while here, branch prediction will be good.
*/
- if (atomic_read(&fclones->fclone_ref) == 1)
+ if (refcount_read(&fclones->fclone_ref) == 1)
goto fastpath;
break;
@@ -637,7 +637,7 @@ static void kfree_skbmem(struct sk_buff *skb)
fclones = container_of(skb, struct sk_buff_fclones, skb2);
break;
}
- if (!atomic_dec_and_test(&fclones->fclone_ref))
+ if (!refcount_dec_and_test(&fclones->fclone_ref))
return;
fastpath:
kmem_cache_free(skbuff_fclone_cache, fclones);
@@ -1018,9 +1018,9 @@ struct sk_buff *skb_clone(struct sk_buff *skb, gfp_t gfp_mask)
return NULL;
if (skb->fclone == SKB_FCLONE_ORIG &&
- atomic_read(&fclones->fclone_ref) == 1) {
+ refcount_read(&fclones->fclone_ref) == 1) {
n = &fclones->skb2;
- atomic_set(&fclones->fclone_ref, 2);
+ refcount_set(&fclones->fclone_ref, 2);
} else {
if (skb_pfmemalloc(skb))
gfp_mask |= __GFP_MEMALLOC;
--
2.7.4
