Messages in this thread Patch in this message | | | From | linmiaohe <> | Subject | [PATCH 1/5] net: Fix potential deadloop in skb_copy_ubufs() | Date | Thu, 6 Aug 2020 19:50:42 +0800 |
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From: Miaohe Lin <linmiaohe@huawei.com>
We could be trapped in deadloop when we try to copy userspace skb frags buffers to kernel with a cloned skb:
[kbox] catch panic event, panic reason:kernel stack overflow [kbox] catch panic event, start logging. CPU: 3 PID: 4083 Comm: insmod Kdump: loaded Tainted: G OE 4.19 #6 Hardware name: linux,dummy-virt (DT) Call trace: dump_backtrace+0x0/0x198 show_stack+0x24/0x30 dump_stack+0xa4/0xcc kbox_panic_notifier_callback+0x1d0/0x310 [kbox] notifier_call_chain+0x5c/0xa0 atomic_notifier_call_chain+0x3c/0x50 panic+0x164/0x314 __stack_chk_fail+0x0/0x28 handle_bad_stack+0xfc/0x108 __bad_stack+0x90/0x94 pskb_expand_head+0x0/0x2c8 pskb_expand_head+0x290/0x2c8 skb_copy_ubufs+0x3cc/0x520 pskb_expand_head+0x290/0x2c8 skb_copy_ubufs+0x3cc/0x520 pskb_expand_head+0x290/0x2c8 skb_copy_ubufs+0x3cc/0x520 pskb_expand_head+0x290/0x2c8 skb_copy_ubufs+0x3cc/0x520 ... pskb_expand_head+0x290/0x2c8 skb_copy_ubufs+0x3cc/0x520 ...
Reproduce code snippet: skb = alloc_skb(UBUF_DATA_LEN, GFP_ATOMIC); clone = skb_clone(skb, GFP_ATOMIC); skb_zcopy_set_nouarg(clone, NULL); pskb_expand_head(skb, 0, 0, GFP_ATOMIC);
Catch this unexpected case and return -EINVAL in skb_orphan_frags() before we call skb_copy_ubufs() to fix it.
Fixes: a6686f2f382b ("skbuff: skb supports zero-copy buffers") Signed-off-by: Miaohe Lin <linmiaohe@huawei.com> --- include/linux/skbuff.h | 3 +++ 1 file changed, 3 insertions(+)
diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h index 0c0377fc00c2..167c8f4cb6e3 100644 --- a/include/linux/skbuff.h +++ b/include/linux/skbuff.h @@ -2753,6 +2753,9 @@ static inline int skb_orphan_frags(struct sk_buff *skb, gfp_t gfp_mask) if (!skb_zcopy_is_nouarg(skb) && skb_uarg(skb)->callback == sock_zerocopy_callback) return 0; + /* If the skb is cloned, return error here or we will be trapped in deadloop. */ + if (unlikely(skb_cloned(skb))) + return -EINVAL; return skb_copy_ubufs(skb, gfp_mask); } -- 2.19.1
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