CriticalFix available

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

Type: advisorySources: OSV

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.

Products: Kernel
Affected versions: Not specified
Fixed versions: 6.1.188, 6.12.109, 6.18.50, 6.6.157, 7.2.4
CVEs: CVE-2026-89634
Confirmed fixed CVEs: Not specified
Updated in this feed: 7 Nov 2026, 03:05 UTC · Revision 1

Source evidence

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

core-osv · Original source

Published 11 Sept 2026, 19:45 UTC

osv:CVE-2026-89634

Kernel

Fixed versions: 6.1.188, 6.6.157, 6.12.109, 6.18.50, 7.2.4

Complete source record

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  "url": "https://osv.dev/vulnerability/CVE-2026-89634",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "smb: client: fix ALIGN() overflow in symlink_data() error context loop",
    "summary": "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.",
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      "modified": "2026-10-28T02:30:49.148222484Z",
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  "source_id": "core-osv",
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