efivarfs: Fix memory leak of efivarfs_fs_info in fs_context error paths

Vulnerability Description

In the Linux kernel, the following vulnerability has been resolved: efivarfs: Fix memory leak of efivarfs_fs_info in fs_context error paths When processing mount options, efivarfs allocates efivarfs_fs_info (sfi) early in fs_context initialization. However, sfi is associated with the superblock and typically freed when the superblock is destroyed. If the fs_context is released (final put) before fill_super is called—such as on error paths or during reconfiguration—the sfi structure would leak, as ownership never transfers to the superblock. Implement the .free callback in efivarfs_context_ops to ensure any allocated sfi is properly freed if the fs_context is torn down before fill_super, preventing this memory leak.

References

• https://git.kernel.org/stable/c/816d36973467d1c9c08a48bdffe4675e219a2e84
• https://git.kernel.org/stable/c/e9fabe7036bb8be6071f39dc38605508f5f57b20
• https://git.kernel.org/stable/c/64e135f1eaba0bbb0cdee859af3328c68d5b9789