Entreprise française de cybersécurité depuis 2004
☎ 03 60 47 09 81 - info@securiteinfo.com
☎ 03 60 47 09 81 - info@securiteinfo.com
In the Linux kernel, the following vulnerability has been resolved:smc: Fix various oops due to inet_sock type confusion.syzbot reported weird splats [0][1] in cipso_v4_sock_setattr() whilefreeing inet_sk(sk)->inet_opt.The address was freed multiple times even though it was read-only memory.cipso_v4_sock_setattr() did nothing wrong, and the root cause was typeconfusion.The cited commit made it possible to create smc_sock as an INET socket.The issue is that struct smc_sock does not have struct inet_sock as thefirst member but hijacks AF_INET and AF_INET6 sk_family, which confusesvarious places.In this case, inet_sock.inet_opt was actually smc_sock.clcsk_data_ready(),which is an address of a function in the text segment. $ pahole -C inet_sock vmlinux struct inet_sock { ... struct ip_options_rcu * inet_opt; /* 784 8 */ $ pahole -C smc_sock vmlinux struct smc_sock { ... void (*clcsk_data_ready)(struct sock *); /* 784 8 */The same issue for another field was reported before. [2][3]At that time, an ugly hack was suggested [4], but it makes both INETand SMC code error-prone and hard to change.Also, yet another variant was fixed by a hacky commit 98d4435efcbf3("net/smc: prevent NULL pointer dereference in txopt_get").Instead of papering over the root cause by such hacks, we should notallow non-INET socket to reuse the INET infra.Let's add inet_sock as the first member of smc_sock.[0]:kvfree_call_rcu(): Double-freed call. rcu_head 000000006921da73WARNING: CPU: 0 PID: 6718 at mm/slab_common.c:1956 kvfree_call_rcu+0x94/0x3f0 mm/slab_common.c:1955Modules linked in:CPU: 0 UID: 0 PID: 6718 Comm: syz.0.17 Tainted: G W 6.16.0-rc4-syzkaller-g7482bb149b9f #0 PREEMPTTainted: [W]=WARNHardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025pstate: 60400005 (nZCv daif +PAN -UAO -TCO -DIT -SSBS BTYPE=--)pc : kvfree_call_rcu+0x94/0x3f0 mm/slab_common.c:1955lr : kvfree_call_rcu+0x94/0x3f0 mm/slab_common.c:1955sp : ffff8000a03a7730x29: ffff8000a03a7730 x28: 00000000fffffff5 x27: 1fffe000184823d3x26: dfff800000000000 x25: ffff0000c2411e9e x24: ffff0000dd88da00x23: ffff8000891ac9a0 x22: 00000000ffffffea x21: ffff8000891ac9a0x20: ffff8000891ac9a0 x19: ffff80008afc2480 x18: 00000000ffffffffx17: 0000000000000000 x16: ffff80008ae642c8 x15: ffff700011ede14cx14: 1ffff00011ede14c x13: 0000000000000004 x12: ffffffffffffffffx11: ffff700011ede14c x10: 0000000000ff0100 x9 : 5fa3c1ffaf0ff000x8 : 5fa3c1ffaf0ff000 x7 : 0000000000000001 x6 : 0000000000000001x5 : ffff8000a03a7078 x4 : ffff80008f766c20 x3 : ffff80008054d360x2 : 0000000000000000 x1 : 0000000000000201 x0 : 0000000000000000Call trace: kvfree_call_rcu+0x94/0x3f0 mm/slab_common.c:1955 (P) cipso_v4_sock_setattr+0x2f0/0x3f4 net/ipv4/cipso_ipv4.c:1914 netlbl_sock_setattr+0x240/0x334 net/netlabel/netlabel_kapi.c:1000 smack_netlbl_add+0xa8/0x158 security/smack/smack_lsm.c:2581 smack_inode_setsecurity+0x378/0x430 security/smack/smack_lsm.c:2912 security_inode_setsecurity+0x118/0x3c0 security/security.c:2706 __vfs_setxattr_noperm+0x174/0x5c4 fs/xattr.c:251 __vfs_setxattr_locked+0x1ec/0x218 fs/xattr.c:295 vfs_setxattr+0x158/0x2ac fs/xattr.c:321 do_setxattr fs/xattr.c:636 [inline] file_setxattr+0x1b8/0x294 fs/xattr.c:646 path_setxattrat+0x2ac/0x320 fs/xattr.c:711 __do_sys_fsetxattr fs/xattr.c:761 [inline] __se_sys_fsetxattr fs/xattr.c:758 [inline] __arm64_sys_fsetxattr+0xc0/0xdc fs/xattr.c:758 __invoke_syscall arch/arm64/kernel/syscall.c:35 [inline] invoke_syscall+0x98/0x2b8 arch/arm64/kernel/syscall.c:49 el0_svc_common+0x130/0x23c arch/arm64/kernel/syscall.c:132 do_el0_svc+0x48/0x58 arch/arm64/kernel/syscall.c:151 el0_svc+0x58/0x180 arch/arm64/kernel/entry-common.c:879 el0t_64_sync_handler+0x84/0x12c arch/arm64/kernel/entry-common.c:898 el0t_64_sync+0x198/0x19c arch/arm64/kernel/entry.S:600[---truncated---
No PoCs from references.
- https://github.com/w4zu/Debian_security