Overview
About vulnerability
In the Linux kernel, the following vulnerability has been resolved:
smb: client: fix off-by-8 bounds check in check_wsl_eas()
The bounds check uses (u8 *)ea + nlen + 1 + vlen as the end of the EA name and value, but ea_data sits at offset sizeof(struct smb2_file_full_ea_info) = 8 from ea, not at offset 0. The strncmp() later reads ea->ea_data[0..nlen-1] and the value bytes follow at ea_data[nlen+1..nlen+vlen], so the actual end is ea->ea_data + nlen + 1
- vlen. Isn’t pointer math fun?
The earlier check (u8 *)ea > end - sizeof(*ea) only guarantees the 8-byte header is in bounds, but since the last EA is placed within 8 bytes of the end of the response, the name and value bytes are read past the end of iov.
Fix this mess all up by using ea->ea_data as the base for the bounds check.
An “untrusted” server can use this to leak up to 8 bytes of kernel heap into the EA name comparison and influence which WSL xattr the data is interpreted as.
Details
- Affected product:
- AlmaLinux 9.2 ESU , CentOS 7 ELS , CentOS 8.4 ELS , CentOS 8.5 ELS , CentOS Stream 8 ELS , RHEL 7 ELS , TuxCare 9.6 ESU
- Affected packages:
- kernel @ 4.18.0 (+6 more)
Fixes
KernelCare state
Live-patch status from KernelCare for each operating system.
| Operating system | Status | Covered kernels |
|---|---|---|
| AlmaLinux 9.6 ESU | Planned | — |
| Debian 13 | Planned | — |