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Miller" , Jakub Kicinski , netdev@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH bpf] bpf: check for data_len before upgrading mss when 6 to 4 Date: Thu, 29 Apr 2021 19:08:23 +0900 Message-Id: <1619690903-1138-1-git-send-email-dseok.yi@samsung.com> X-Mailer: git-send-email 2.7.4 X-Brightmail-Tracker: H4sIAAAAAAAAA+NgFvrNKsWRmVeSWpSXmKPExsWy7bCmhe72jq4EgxlHtS2+/57NbPHl5212 i89HjrNZLF74jdlizvkWFosr0/4wWjTtWMFk8eLDE0aL5/t6mSwubOtjtbi8aw6bxbEFYhY/ D59htnixZAajA5/HlpU3mTwmNr9j99g56y67R9eNS8wem1Z1snn0bVnF6PF5k1wAe1SOTUZq YkpqkUJqXnJ+SmZeuq2Sd3C8c7ypmYGhrqGlhbmSQl5ibqqtkotPgK5bZg7QyUoKZYk5pUCh gMTiYiV9O5ui/NKSVIWM/OISW6XUgpScAkPDAr3ixNzi0rx0veT8XCtDAwMjU6DKhJyM7dPm shUc5qzYcW4hUwPjffYuRg4OCQETiVPzHbsYuTiEBHYwSmzvOMMO4XxilFj6cxILhPONUWLW 3CNMXYycYB2LV/+CSuxllFjxYB1Uyw9GiQMvW1lAqtgENCT2v3vBCmKLCIhLLDi2gQmkiFng HLPEpflzGEESwgL+ErMfvGQGsVkEVCV+XPsE1sAr4Cyx7P9vdoh1chI3z3UygzRLCHxll1jb 0M0CkXCR2LF5ExuELSzx6vgWqAYpiZf9bVDf1Uu0dsdA9PYwSlzZ9wSq11hi1rN2RpAaZgFN ifW79CHKlSWO3AKrYBbgk+g4/BdqCq9ER5sQhKkkMfFLPMQMCYkXJydDzfOQmH21E+wWIYFY if/vT7NPYJSdhTB+ASPjKkax1ILi3PTUYqMCY+Q42sQIToVa7jsYZ7z9oHeIkYmD8RCjBAez kgjv73WdCUK8KYmVValF+fFFpTmpxYcYTYGhNZFZSjQ5H5iM80riDU2NzMwMLE0tTM2MLJTE eX+m1iUICaQnlqRmp6YWpBbB9DFxcEo1MNneCf2+dpnwtCcxOmp/FV6bC7CK/XJykHbawpi/ TuN2j1QWj+tCnbNXqvX8dUQ99E/1K5rpiOheffbSii3FYtGVK89kTkj4bvMXYHitXNbnfmfd g0Ld54cnmyzkYUv6ZLrsy0MDo7uMZqHbmrnszr0vy3Vh0+yYzvd01cc+lUnF6rXnnM6+abyg 1Pgt7wfjrS/b+fcmbtO7rpAipbXrpPKH3sOv70b11ATmRS/gKjgQet/9T/OTKi+txbvv5ihu sTqw3N72TVykwBS7F1OLZ6+6l67baMjW9s/Po+GkZbJk4rNe/WUyfLfTpk04nDBLYL/6pMvn fi00ne9Qa2smGZO34KKviZzUkVNTtaLKlViKMxINtZiLihMBRryFlQ4EAAA= X-Brightmail-Tracker: H4sIAAAAAAAAA+NgFlrNLMWRmVeSWpSXmKPExsWy7bCSvO72jq4Eg43buCy+/57NbPHl5212 i89HjrNZLF74jdlizvkWFosr0/4wWjTtWMFk8eLDE0aL5/t6mSwubOtjtbi8aw6bxbEFYhY/ D59htnixZAajA5/HlpU3mTwmNr9j99g56y67R9eNS8wem1Z1snn0bVnF6PF5k1wAexSXTUpq TmZZapG+XQJXxvZpc9kKDnNW7Di3kKmB8T57FyMnh4SAicTi1b9Yuhi5OIQEdjNKNPffZO1i 5ABKSEjs2uwKUSMscb/lCCtEzTdGiak7X7GAJNgENCT2v3vBCmKLCIhLLDi2gQmkiFngFrNE 98k5jCAJYQFfiYaZ38G2sQioSvy49gmsgVfAWWLZ/99QV8hJ3DzXyTyBkWcBI8MqRsnUguLc 9NxiwwLDvNRyveLE3OLSvHS95PzcTYzg8NTS3MG4fdUHvUOMTByMhxglOJiVRHh/r+tMEOJN SaysSi3Kjy8qzUktPsQozcGiJM57oetkvJBAemJJanZqakFqEUyWiYNTqoHJrCna96D0zSvH ufolTp7banuD5/ObwPZX7w6YanoZvXE7sCnzPKO+xtqfj5UfWDye7XjnVN6Hv3tns7+QT0le 9uO01Uafxqe6z47Fql6bHn/g8qPTW5tu8tutzsyIStp4/1l+q+cd1t8x8w2ieQp8Lfouvda+ v5x3H4+tierR4Cu/vnmfFbH6kfpTTTVg2l2L6gkxa2esPvW2b4Ig/9cmbeuSXe0vHl+MulRQ vnvBT4XNKUzBO5447Np40aPn9epN1/YdaOf1ml7oqF9cctv6QN26Ta633543ZXdvEfM48D2c T1GqPb2fN+bEtSi5+rDpuqZ34pXjFs4pL3W6p8usPHlR8KkDP0OS+14FnGBhUGIpzkg01GIu Kk4EANEaXsW+AgAA X-CMS-MailID: 20210429102143epcas2p4c8747c09a9de28f003c20389c050394a X-Msg-Generator: CA Content-Type: text/plain; charset="utf-8" X-Sendblock-Type: AUTO_CONFIDENTIAL CMS-TYPE: 102P DLP-Filter: Pass X-CFilter-Loop: Reflected X-CMS-RootMailID: 20210429102143epcas2p4c8747c09a9de28f003c20389c050394a References: Precedence: bulk List-ID: X-Mailing-List: bpf@vger.kernel.org tcp_gso_segment check for the size of GROed payload if it is bigger than the mss. bpf_skb_proto_6_to_4 increases mss, but the mss can be bigger than the size of GROed payload unexpectedly if data_len is not big enough. Assume that skb gso_size = 1372 and data_len = 8. bpf_skb_proto_6_to_4 would increse the gso_size to 1392. tcp_gso_segment will get an error with 1380 <= 1392. Check for the size of GROed payload if it is really bigger than target mss when increase mss. Fixes: 6578171a7ff0 (bpf: add bpf_skb_change_proto helper) Signed-off-by: Dongseok Yi --- net/core/filter.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/net/core/filter.c b/net/core/filter.c index 9323d34..3f79e3c 100644 --- a/net/core/filter.c +++ b/net/core/filter.c @@ -3308,7 +3308,9 @@ static int bpf_skb_proto_6_to_4(struct sk_buff *skb) } /* Due to IPv4 header, MSS can be upgraded. */ - skb_increase_gso_size(shinfo, len_diff); + if (skb->data_len > len_diff) + skb_increase_gso_size(shinfo, len_diff); + /* Header must be checked, and gso_segs recomputed. */ shinfo->gso_type |= SKB_GSO_DODGY; shinfo->gso_segs = 0; -- 2.7.4