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| author | Antoine Tenart <atenart@kernel.org> | 2021-07-09 19:16:09 +0300 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2021-07-09 21:26:27 +0300 |
| commit | 28b34f01a73435a754956ebae826e728c03ffa38 (patch) | |
| tree | e0d89304323b75149af9a7339d759b4176333084 /net/core/dev.c | |
| parent | 358ed624207012f03318235017ac6fb41f8af592 (diff) | |
| download | linux-28b34f01a73435a754956ebae826e728c03ffa38.tar.xz | |
net: do not reuse skbuff allocated from skbuff_fclone_cache in the skb cache
Some socket buffers allocated in the fclone cache (in __alloc_skb) can
end-up in the following path[1]:
napi_skb_finish
__kfree_skb_defer
napi_skb_cache_put
The issue is napi_skb_cache_put is not fclone friendly and will put
those skbuff in the skb cache to be reused later, although this cache
only expects skbuff allocated from skbuff_head_cache. When this happens
the skbuff is eventually freed using the wrong origin cache, and we can
see traces similar to:
[ 1223.947534] cache_from_obj: Wrong slab cache. skbuff_head_cache but object is from skbuff_fclone_cache
[ 1223.948895] WARNING: CPU: 3 PID: 0 at mm/slab.h:442 kmem_cache_free+0x251/0x3e0
[ 1223.950211] Modules linked in:
[ 1223.950680] CPU: 3 PID: 0 Comm: swapper/3 Not tainted 5.13.0+ #474
[ 1223.951587] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.14.0-3.fc34 04/01/2014
[ 1223.953060] RIP: 0010:kmem_cache_free+0x251/0x3e0
Leading sometimes to other memory related issues.
Fix this by using __kfree_skb for fclone skbuff, similar to what is done
the other place __kfree_skb_defer is called.
[1] At least in setups using veth pairs and tunnels. Building a kernel
with KASAN we can for example see packets allocated in
sk_stream_alloc_skb hit the above path and later the issue arises
when the skbuff is reused.
Fixes: 9243adfc311a ("skbuff: queue NAPI_MERGED_FREE skbs into NAPI cache instead of freeing")
Cc: Alexander Lobakin <alobakin@pm.me>
Signed-off-by: Antoine Tenart <atenart@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/core/dev.c')
| -rw-r--r-- | net/core/dev.c | 2 |
1 files changed, 2 insertions, 0 deletions
diff --git a/net/core/dev.c b/net/core/dev.c index 03c95a0867bb..64b21f0a2048 100644 --- a/net/core/dev.c +++ b/net/core/dev.c @@ -6234,6 +6234,8 @@ static gro_result_t napi_skb_finish(struct napi_struct *napi, case GRO_MERGED_FREE: if (NAPI_GRO_CB(skb)->free == NAPI_GRO_FREE_STOLEN_HEAD) napi_skb_free_stolen_head(skb); + else if (skb->fclone != SKB_FCLONE_UNAVAILABLE) + __kfree_skb(skb); else __kfree_skb_defer(skb); break; |