smb: client: fix ALIGN() overflow in symlink_data() error context loop

Overview

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

smb: client: fix ALIGN() overflow in symlink_data() error context loop

The check added by commit 7d9a7f1f96cd ("smb/client: fix possible infinite loop and oob read in symlink_data()") compared the post-ALIGN length against the remaining buffer, but ALIGN() itself can overflow: for ErrorDataLength near UINT32_MAX (e.g. 0xFFFFFFF9), ALIGN(x, 8) wraps to 0, so the subsequent bounds check passes, and the loop advances by zero bytes leaving 'p' pointing into stale data.

Fix by checking the raw ErrorDataLength against the remaining space before applying ALIGN(), then checking again after. Since raw_len is bounded by the buffer, raw_len + 7 cannot overflow, so the second check is an exact post-alignment bounds guard.

Affected

• Linux >= 76894f3e2f71177747b8b4763fb180e800279585 < 2b4a25baa0b936fef6915c0459925077b324ecaf
• Linux >= 76894f3e2f71177747b8b4763fb180e800279585 < b89d678f9eafcf8d74885983166ba26b40a04ea0
• Linux >= 76894f3e2f71177747b8b4763fb180e800279585 < 657372ba6ea50b4474d2a6a610097eae8cd1f3e9
• Linux >= 76894f3e2f71177747b8b4763fb180e800279585 < 1f824f61d1df52392eaf0b74dfa5659d724fde30
• Linux >= 76894f3e2f71177747b8b4763fb180e800279585 < 62a3025983c8c735a3c6fc85a59316f31b59af07
• Linux >= 76894f3e2f71177747b8b4763fb180e800279585 < 62656b024efc21c3230eade1a847f25871c3d2bb
• Linux 2d046892a493d9760c35fdaefc3017f27f91b621
• Linux >= 6.0.16 < 6.1
• Linux 6.1

Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.

Vendor advisories

• Red Hat VEX · Moderate · affected: Red Hat Enterprise Linux 10, Red Hat Enterprise Linux 9, Red Hat OpenShift Container Platform 4 · no fix planned: Red Hat Enterprise Linux 10, Red Hat Enterprise Linux 9, Red Hat OpenShift Container Platform 4 · updated 2026-09-14 · vex