CVE-2024-35841 net: tls, fix WARNIING in __sk_msg_free

2024-05-1714:27:31

Linux

www.cve.org

linux kernel

net security

tls code

cve-2024-35841

6.6 Medium

AI Score

Confidence

High

0.0004 Low

EPSS

Percentile

15.5%

JSON

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.

CNA Affected

[
  {
    "product": "Linux",
    "vendor": "Linux",
    "defaultStatus": "unaffected",
    "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
    "programFiles": [
      "net/tls/tls_sw.c"
    ],
    "versions": [
      {
        "version": "fe1e81d4f73b",
        "lessThan": "02e368eb1444",
        "status": "affected",
        "versionType": "git"
      },
      {
        "version": "fe1e81d4f73b",
        "lessThan": "294e7ea85f34",
        "status": "affected",
        "versionType": "git"
      },
      {
        "version": "fe1e81d4f73b",
        "lessThan": "dc9dfc8dc629",
        "status": "affected",
        "versionType": "git"
      }
    ]
  },
  {
    "product": "Linux",
    "vendor": "Linux",
    "defaultStatus": "affected",
    "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
    "programFiles": [
      "net/tls/tls_sw.c"
    ],
    "versions": [
      {
        "version": "6.5",
        "status": "affected"
      },
      {
        "version": "0",
        "lessThan": "6.5",
        "status": "unaffected",
        "versionType": "custom"
      },
      {
        "version": "6.6.14",
        "lessThanOrEqual": "6.6.*",
        "status": "unaffected",
        "versionType": "custom"
      },
      {
        "version": "6.7.2",
        "lessThanOrEqual": "6.7.*",
        "status": "unaffected",
        "versionType": "custom"
      },
      {
        "version": "6.8",
        "lessThanOrEqual": "*",
        "status": "unaffected",
        "versionType": "original_commit_for_fix"
      }
    ]
  }
]