In the Linux kernel, the following vulnerability has been resolved:tcp: Use refcount_inc_not_zero() in tcp_twsk_unique().Anderson Nascimento reported a use-after-free splat in tcp_twsk_unique()with nice analysis.Since commit ec94c2696f0b ("tcp/dccp: avoid one atomic operation fortimewait hashdance"), inet_twsk_hashdance() sets TIME-WAIT socket'ssk_refcnt after putting it into ehash and releasing the bucket lock.Thus, there is a small race window where other threads could try toreuse the port during connect() and call sock_hold() in tcp_twsk_unique()for the TIME-WAIT socket with zero refcnt.If that happens, the refcnt taken by tcp_twsk_unique() is overwrittenand sock_put() will cause underflow, triggering a real use-after-freesomewhere else.To avoid the use-after-free, we need to use refcount_inc_not_zero() intcp_twsk_unique() and give up on reusing the port if it returns false.[0]:refcount_t: addition on 0; use-after-free.WARNING: CPU: 0 PID: 1039313 at lib/refcount.c:25 refcount_warn_saturate+0xe5/0x110CPU: 0 PID: 1039313 Comm: trigger Not tainted 6.8.6-200.fc39.x86_64 #1Hardware name: VMware, Inc. VMware20,1/440BX Desktop Reference Platform, BIOS VMW201.00V.21805430.B64.2305221830 05/22/2023RIP: 0010:refcount_warn_saturate+0xe5/0x110Code: 42 8e ff 0f 0b c3 cc cc cc cc 80 3d aa 13 ea 01 00 0f 85 5e ff ff ff 48 c7 c7 f8 8e b7 82 c6 05 96 13 ea 01 01 e8 7b 42 8e ff <0f> 0b c3 cc cc cc cc 48 c7 c7 50 8f b7 82 c6 05 7a 13 ea 01 01 e8RSP: 0018:ffffc90006b43b60 EFLAGS: 00010282RAX: 0000000000000000 RBX: ffff888009bb3ef0 RCX: 0000000000000027RDX: ffff88807be218c8 RSI: 0000000000000001 RDI: ffff88807be218c0RBP: 0000000000069d70 R08: 0000000000000000 R09: ffffc90006b439f0R10: ffffc90006b439e8 R11: 0000000000000003 R12: ffff8880029ede84R13: 0000000000004e20 R14: ffffffff84356dc0 R15: ffff888009bb3ef0FS: 00007f62c10926c0(0000) GS:ffff88807be00000(0000) knlGS:0000000000000000CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033CR2: 0000000020ccb000 CR3: 000000004628c005 CR4: 0000000000f70ef0PKRU: 55555554Call Trace:
No PoCs from references.
- https://github.com/alleleintel/research
- https://github.com/tanjiti/sec_profile
- https://github.com/xairy/linux-kernel-exploitation