In the Linux kernel, the following vulnerability has been resolved: ksmbd: fix out-of-bounds write in smb2_get_ea() EA alignment smb2_get_ea() applies 4-byte alignment padding via memset() after writing each EA entry

Overview

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

ksmbd: fix out-of-bounds write in smb2_get_ea() EA alignment

smb2_get_ea() applies 4-byte alignment padding via memset() after writing each EA entry. The bounds check on buf_free_len is performed before the value memcpy, but the alignment memset fires unconditionally afterward with no check on remaining space.

When the EA value exactly fills the remaining buffer (buf_free_len == 0 after value subtraction), the alignment memset writes 1-3 NUL bytes past the buf_free_len boundary. In compound requests where the response buffer is shared across commands, the first command (e.g., READ) can consume most of the buffer, leaving a tight remainder for the QUERY_INFO EA response. The alignment memset then overwrites past the physical kvmalloc allocation into adjacent kernel heap memory.

Add a bounds check before the alignment memset to ensure buf_free_len can accommodate the padding bytes.

This is the same bug pattern fixed by commit beef2634f81f ("ksmbd: fix potencial OOB in get_file_all_info() for compound requests") and commit fda9522ed6af ("ksmbd: fix OOB write in QUERY_INFO for compound requests"), both of which added bounds checks before unconditional writes in QUERY_INFO response handlers.

Affected

• linux_kernel >= 5.15.145, < 5.16
• linux_kernel >= 6.1.71, < 6.2
• linux_kernel >= 6.6, < 6.6.136
• linux_kernel >= 6.7, < 6.12.84
• linux_kernel >= 6.13, < 6.18.25
• linux_kernel >= 6.19, < 7.0.2

Remediation

Upgrade past the affected range:

• linux_kernel 7.0.2