lkml.org 
[lkml]   [2017]   [Jun]   [30]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
From
Subject[PATCH 06/17] net: convert sk_buff_fclones.fclone_ref from atomic_t to refcount_t
Date
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@intel.com>
Signed-off-by: Hans Liljestrand <ishkamiel@gmail.com>
Signed-off-by: Kees Cook <keescook@chromium.org>
Signed-off-by: David Windsor <dwindsor@gmail.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 90cbd86..d0b9f38 100644
--- a/include/linux/skbuff.h
+++ b/include/linux/skbuff.h
@@ -915,7 +915,7 @@ struct sk_buff_fclones {

struct sk_buff skb2;

- atomic_t fclone_ref;
+ refcount_t fclone_ref;
};

/**
@@ -935,7 +935,7 @@ 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 45dc662..659dfc0 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);
@@ -1027,9 +1027,9 @@ 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
\
 
 \ /
  Last update: 2017-06-30 23:11    [W:0.099 / U:3.164 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site