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| author | Eric Dumazet <eric.dumazet@gmail.com> | 2009-07-08 19:36:05 +0000 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2009-07-11 20:26:19 -0700 |
| commit | e912b1142be8f1e2c71c71001dc992c6e5eb2ec1 (patch) | |
| tree | 9812c7d3e5431852d25bc15860830413ff15dc51 /net | |
| parent | e594e96e8a14101a6decabf6746bd5186287debc (diff) | |
| download | linux-2.6-e912b1142be8f1e2c71c71001dc992c6e5eb2ec1.tar.gz linux-2.6-e912b1142be8f1e2c71c71001dc992c6e5eb2ec1.tar.xz | |
net: sk_prot_alloc() should not blindly overwrite memory
Some sockets use SLAB_DESTROY_BY_RCU, and our RCU code correctness
depends on sk->sk_nulls_node.next being always valid. A NULL
value is not allowed as it might fault a lockless reader.
Current sk_prot_alloc() implementation doesnt respect this hypothesis,
calling kmem_cache_alloc() with __GFP_ZERO. Just call memset() around
the forbidden field.
Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net')
| -rw-r--r-- | net/core/sock.c | 19 |
1 files changed, 17 insertions, 2 deletions
diff --git a/net/core/sock.c b/net/core/sock.c index 6354863b1c6..ba5d2116aea 100644 --- a/net/core/sock.c +++ b/net/core/sock.c @@ -939,8 +939,23 @@ static struct sock *sk_prot_alloc(struct proto *prot, gfp_t priority, struct kmem_cache *slab; slab = prot->slab; - if (slab != NULL) - sk = kmem_cache_alloc(slab, priority); + if (slab != NULL) { + sk = kmem_cache_alloc(slab, priority & ~__GFP_ZERO); + if (!sk) + return sk; + if (priority & __GFP_ZERO) { + /* + * caches using SLAB_DESTROY_BY_RCU should let + * sk_node.next un-modified. Special care is taken + * when initializing object to zero. + */ + if (offsetof(struct sock, sk_node.next) != 0) + memset(sk, 0, offsetof(struct sock, sk_node.next)); + memset(&sk->sk_node.pprev, 0, + prot->obj_size - offsetof(struct sock, + sk_node.pprev)); + } + } else sk = kmalloc(prot->obj_size, priority); |