ghsa-5c5w-jm9h-wvq9
Vulnerability from github
In the Linux kernel, the following vulnerability has been resolved:
net: tls, fix WARNIING in __sk_msg_free
A splice with MSG_SPLICE_PAGES will cause tls code to use the tls_sw_sendmsg_splice path in the TLS sendmsg code to move the user provided pages from the msg into the msg_pl. This will loop over the msg until msg_pl is full, checked by sk_msg_full(msg_pl). The user can also set the MORE flag to hint stack to delay sending until receiving more pages and ideally a full buffer.
If the user adds more pages to the msg than can fit in the msg_pl scatterlist (MAX_MSG_FRAGS) we should ignore the MORE flag and send the buffer anyways.
What actually happens though is we abort the msg to msg_pl scatterlist setup and then because we forget to set 'full record' indicating we can no longer consume data without a send we fallthrough to the 'continue' path which will check if msg_data_left(msg) has more bytes to send and then attempts to fit them in the already full msg_pl. Then next iteration of sender doing send will encounter a full msg_pl and throw the warning in the syzbot report.
To fix simply check if we have a full_record in splice code path and if not send the msg regardless of MORE flag.
{
"affected": [],
"aliases": [
"CVE-2024-35841"
],
"database_specific": {
"cwe_ids": [],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2024-05-17T15:15:21Z",
"severity": null
},
"details": "In the Linux kernel, the following vulnerability has been resolved:\n\nnet: tls, fix WARNIING in __sk_msg_free\n\nA splice with MSG_SPLICE_PAGES will cause tls code to use the\ntls_sw_sendmsg_splice path in the TLS sendmsg code to move the user\nprovided pages from the msg into the msg_pl. This will loop over the\nmsg until msg_pl is full, checked by sk_msg_full(msg_pl). The user\ncan also set the MORE flag to hint stack to delay sending until receiving\nmore pages and ideally a full buffer.\n\nIf the user adds more pages to the msg than can fit in the msg_pl\nscatterlist (MAX_MSG_FRAGS) we should ignore the MORE flag and send\nthe buffer anyways.\n\nWhat actually happens though is we abort the msg to msg_pl scatterlist\nsetup and then because we forget to set \u0027full record\u0027 indicating we\ncan no longer consume data without a send we fallthrough to the \u0027continue\u0027\npath which will check if msg_data_left(msg) has more bytes to send and\nthen attempts to fit them in the already full msg_pl. Then next\niteration of sender doing send will encounter a full msg_pl and throw\nthe warning in the syzbot report.\n\nTo fix simply check if we have a full_record in splice code path and\nif not send the msg regardless of MORE flag.",
"id": "GHSA-5c5w-jm9h-wvq9",
"modified": "2024-05-17T15:31:12Z",
"published": "2024-05-17T15:31:12Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2024-35841"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/02e368eb1444a4af649b73cbe2edd51780511d86"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/294e7ea85f34748f04e5f3f9dba6f6b911d31aa8"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/dc9dfc8dc629e42f2234e3327b75324ffc752bc9"
}
],
"schema_version": "1.4.0",
"severity": []
}