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Message-Id: <1498650906-12907-7-git-send-email-elena.reshetova@intel.com>
Date: Wed, 28 Jun 2017 14:54:55 +0300
From: Elena Reshetova <elena.reshetova@...el.com>
To: netdev@...r.kernel.org
Cc: bridge@...ts.linux-foundation.org, linux-kernel@...r.kernel.org,
kuznet@....inr.ac.ru, jmorris@...ei.org, kaber@...sh.net,
stephen@...workplumber.org, peterz@...radead.org,
keescook@...omium.org, Elena Reshetova <elena.reshetova@...el.com>,
Hans Liljestrand <ishkamiel@...il.com>,
David Windsor <dwindsor@...il.com>
Subject: [PATCH 06/17] net: convert sk_buff_fclones.fclone_ref from atomic_t to refcount_t
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@...el.com>
Signed-off-by: Hans Liljestrand <ishkamiel@...il.com>
Signed-off-by: Kees Cook <keescook@...omium.org>
Signed-off-by: David Windsor <dwindsor@...il.com>
---
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 7498e64..5e26b4c 100644
--- a/include/linux/skbuff.h
+++ b/include/linux/skbuff.h
@@ -948,7 +948,7 @@ struct sk_buff_fclones {
struct sk_buff skb2;
- atomic_t fclone_ref;
+ refcount_t fclone_ref;
};
/**
@@ -968,7 +968,7 @@ 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 f04c1f8..1bd9352 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
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