CVE-2024-26692 smb: Fix regression in writes when non-standard maximum write size negotiated

2024-04-0314:54:53

Linux

www.cve.org

linux kernel

data corruption

netfs change

maximum write size

regression fix

server negotiation

6.7 Medium

AI Score

Confidence

Low

0.0004 Low

EPSS

Percentile

15.7%

JSON

In the Linux kernel, the following vulnerability has been resolved:

smb: Fix regression in writes when non-standard maximum write size negotiated

The conversion to netfs in the 6.3 kernel caused a regression when
maximum write size is set by the server to an unexpected value which is
not a multiple of 4096 (similarly if the user overrides the maximum
write size by setting mount parm “wsize”, but sets it to a value that
is not a multiple of 4096). When negotiated write size is not a
multiple of 4096 the netfs code can skip the end of the final
page when doing large sequential writes, causing data corruption.

This section of code is being rewritten/removed due to a large
netfs change, but until that point (ie for the 6.3 kernel until now)
we can not support non-standard maximum write sizes.

Add a warning if a user specifies a wsize on mount that is not
a multiple of 4096 (and round down), also add a change where we
round down the maximum write size if the server negotiates a value
that is not a multiple of 4096 (we also have to check to make sure that
we do not round it down to zero).

CNA Affected

[
  {
    "product": "Linux",
    "vendor": "Linux",
    "defaultStatus": "unaffected",
    "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
    "programFiles": [
      "fs/smb/client/connect.c",
      "fs/smb/client/fs_context.c"
    ],
    "versions": [
      {
        "version": "d08089f649a0",
        "lessThan": "4145ccff546e",
        "status": "affected",
        "versionType": "git"
      },
      {
        "version": "d08089f649a0",
        "lessThan": "63c35afd50e2",
        "status": "affected",
        "versionType": "git"
      },
      {
        "version": "d08089f649a0",
        "lessThan": "4860abb91f3d",
        "status": "affected",
        "versionType": "git"
      }
    ]
  },
  {
    "product": "Linux",
    "vendor": "Linux",
    "defaultStatus": "affected",
    "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
    "programFiles": [
      "fs/smb/client/connect.c",
      "fs/smb/client/fs_context.c"
    ],
    "versions": [
      {
        "version": "6.3",
        "status": "affected"
      },
      {
        "version": "0",
        "lessThan": "6.3",
        "status": "unaffected",
        "versionType": "custom"
      },
      {
        "version": "6.6.18",
        "lessThanOrEqual": "6.6.*",
        "status": "unaffected",
        "versionType": "custom"
      },
      {
        "version": "6.7.6",
        "lessThanOrEqual": "6.7.*",
        "status": "unaffected",
        "versionType": "custom"
      },
      {
        "version": "6.8",
        "lessThanOrEqual": "*",
        "status": "unaffected",
        "versionType": "original_commit_for_fix"
      }
    ]
  }
]