vsock: Fix transport_{g2h,h2g} TOCTOU

Vulnerability Description

In the Linux kernel, the following vulnerability has been resolved: vsock: Fix transport_{g2h,h2g} TOCTOU vsock_find_cid() and vsock_dev_do_ioctl() may race with module unload. transport_{g2h,h2g} may become NULL after the NULL check. Introduce vsock_transport_local_cid() to protect from a potential null-ptr-deref. KASAN: null-ptr-deref in range [0x0000000000000118-0x000000000000011f] RIP: 0010:vsock_find_cid+0x47/0x90 Call Trace: __vsock_bind+0x4b2/0x720 vsock_bind+0x90/0xe0 __sys_bind+0x14d/0x1e0 __x64_sys_bind+0x6e/0xc0 do_syscall_64+0x92/0x1c0 entry_SYSCALL_64_after_hwframe+0x4b/0x53 KASAN: null-ptr-deref in range [0x0000000000000118-0x000000000000011f] RIP: 0010:vsock_dev_do_ioctl.isra.0+0x58/0xf0 Call Trace: __x64_sys_ioctl+0x12d/0x190 do_syscall_64+0x92/0x1c0 entry_SYSCALL_64_after_hwframe+0x4b/0x53

References

• https://git.kernel.org/stable/c/c5496ee685c48ed1cc183cd4263602579bb4a615
• https://git.kernel.org/stable/c/80d7dc15805a93d520a249ac6d13d4f4df161c1b
• https://git.kernel.org/stable/c/5752d8dbb3dfd7f1a9faf0f65377e60826ea9a17
• https://git.kernel.org/stable/c/401239811fa728fcdd53e360a91f157ffd23e1f4
• https://git.kernel.org/stable/c/3734d78210cceb2ee5615719a62a5c55ed381ff8
• https://git.kernel.org/stable/c/6a1bcab67bea797d83aa9dd948a0ac6ed52d121d
• https://git.kernel.org/stable/c/209fd720838aaf1420416494c5505096478156b4