i2c: stub: Reject I2C block transfers with invalid length
In the Linux kernel, the following vulnerability has been resolved: i2c: stub: Reject I2C block transfers with invalid length The I2C_SMBUS_I2C_BLOCK_DATA case in stub_xfer() uses data->block[0] as the transfer length. The existing check only clamps it to avoid overrunning the chip->words[256] register array, but does not validate it against I2C_SMBUS_BLOCK_MAX (32), which is the limit of the union i2c_smbus_data.block buffer (34 bytes total). The driver is a development/test tool (CONFIG_I2C_STUB=m, not built by default) that must be loaded with a chip_addr= parameter. A local user with access to /dev/i2c-* can issue an I2C_SMBUS ioctl with I2C_SMBUS_I2C_BLOCK_DATA and data->block[0] > 32, causing stub_xfer() to read or write past the end of the union i2c_smbus_data.block buffer: BUG: KASAN: stack-out-of-bounds in stub_xfer (drivers/i2c/i2c-stub.c:223) Read of size 1 at addr ffff88800abcfd92 by task exploit/81 Call Trace: stub_xfer (drivers/i2c/i2c-stub.c:223) __i2c_smbus_xfer (drivers/i2c/i2c-core-smbus.c:593) i2c_smbus_xfer (drivers/i2c/i2c-core-smbus.c:536) i2cdev_ioctl_smbus (drivers/i2c/i2c-dev.c:391) i2cdev_ioctl (drivers/i2c/i2c-dev.c:478) __x64_sys_ioctl (fs/ioctl.c:583) do_syscall_64 (arch/x86/entry/syscall_64.c:94) entry_SYSCALL_64_after_hwframe (arch/x86/entry/entry_64.S:130) The bug exists because i2c-stub implements .smbus_xfer directly, bypassing the I2C_SMBUS_BLOCK_MAX validation in i2c_smbus_xfer_emulated(). The I2C_SMBUS_BLOCK_DATA case in the same function
CVE-2026-64191
Primary source · Revision 1
Imported from structured advisory data. Source references identify upstream records or fields; verify affected versions and your deployed configuration.
Security context
Source reference: cve:CVE-2026-64191
Linux
Source reference: /containers/cna/affected/0/product
- Affected versions
- Not stated in this record
- Fixed versions
- Not stated in this record
- Prerequisites
- Not stated in this record
Linux
Source reference: /containers/cna/affected/1/product
- Affected versions
- Not stated in this record
- Fixed versions
- Not stated in this record
- Prerequisites
- Not stated in this record
Structured affected-version data
Original package identities and version rules from this source.
[
{
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"product": "Linux",
"versions": [
{
"status": "affected",
"version": "4710317891e4824ce1510a6b5066abbd3e917750",
"lessThan": "7e9072dbd5f2f17934751873450d2c22080ead80",
"versionType": "git"
},
{
"status": "affected",
"version": "4710317891e4824ce1510a6b5066abbd3e917750",
"lessThan": "21e87f336ac6303fed54a69b1d0d79a23b25c8d0",
"versionType": "git"
},
{
"status": "affected",
"version": "4710317891e4824ce1510a6b5066abbd3e917750",
"lessThan": "3fd225f3e4cd67ec8ddab1afed9da03c7c43537c",
"versionType": "git"
},
{
"status": "affected",
"version": "4710317891e4824ce1510a6b5066abbd3e917750",
"lessThan": "1c4ffe6b4f04365485ed58d64c9bb86b46fc9037",
"versionType": "git"
},
{
"status": "affected",
"version": "4710317891e4824ce1510a6b5066abbd3e917750",
"lessThan": "4bd8635f28c135a08aac6badcd7d9b5cdb34335f",
"versionType": "git"
},
{
"status": "affected",
"version": "4710317891e4824ce1510a6b5066abbd3e917750",
"lessThan": "5f4d2bd028ebb6e4c09a9d64842546022321d4a7",
"versionType": "git"
},
{
"status": "affected",
"version": "4710317891e4824ce1510a6b5066abbd3e917750",
"lessThan": "0526931b16e5a118d367b7bfce7d797e63f7ac69",
"versionType": "git"
},
{
"status": "affected",
"version": "4710317891e4824ce1510a6b5066abbd3e917750",
"lessThan": "6036b5067a8199ba7a2dc7b377d4b9dd276d5f9e",
"versionType": "git"
}
],
"programFiles": [
"drivers/i2c/i2c-stub.c"
],
"defaultStatus": "unaffected"
},
{
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"product": "Linux",
"versions": [
{
"status": "affected",
"version": "2.6.33"
},
{
"status": "unaffected",
"version": "0",
"lessThan": "2.6.33",
"versionType": "semver"
},
{
"status": "unaffected",
"version": "5.10.260",
"versionType": "semver",
"lessThanOrEqual": "5.10.*"
},
{
"status": "unaffected",
"version": "5.15.211",
"versionType": "semver",
"lessThanOrEqual": "5.15.*"
},
{
"status": "unaffected",
"version": "6.1.177",
"versionType": "semver",
"lessThanOrEqual": "6.1.*"
},
{
"status": "unaffected",
"version": "6.6.144",
"versionType": "semver",
"lessThanOrEqual": "6.6.*"
},
{
"status": "unaffected",
"version": "6.12.95",
"versionType": "semver",
"lessThanOrEqual": "6.12.*"
},
{
"status": "unaffected",
"version": "6.18.37",
"versionType": "semver",
"lessThanOrEqual": "6.18.*"
},
{
"status": "unaffected",
"version": "7.0.14",
"versionType": "semver",
"lessThanOrEqual": "7.0.*"
},
{
"status": "unaffected",
"version": "7.1",
"versionType": "original_commit_for_fix",
"lessThanOrEqual": "*"
}
],
"programFiles": [
"drivers/i2c/i2c-stub.c"
],
"defaultStatus": "affected"
}
]- Related CVEs
- CVE-2026-64191
Source reference:
/cveMetadata/cveId
Publisher severity
high
Source reference: /containers/cna/metrics
- Event
- #40973 · Revision 1
- Added to Heist Feed
- Publisher date