smc: Fix various oops due to inet_sock type confusion. ...
syzbot reported weird splats [0][1] in cipso_v4_sock_setattr() while
freeing 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 type
confusion.
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 the
first member but hijacks AF_INET and AF_INET6 sk_family, which confuses
various 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 INET
and SMC code error-prone and hard to change.
Also, yet another variant was fixed by a hacky commit 98d4435efc#0 PREEMPT
Tainted: [W]=WARN
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025
pstate: 60400005 (nZCv daif +PAN -UAO -TCO -DIT -SSBS BTYPE=--)
pc : kvfree_call_rcu+0x94/0x3f0 mm/slab_common.c:1955
lr : kvfree_call_rcu+0x94/0x3f0 mm/slab_common.c:1955
sp : ffff8000a03a7730
x29: ffff8000a03a7730 x28: 00000000fffffff5 x27: 1fffe000184823d3
x26: dfff800000000000 x25: ffff0000c2411e9e x24: ffff0000dd88da00
x23: ffff8000891ac9a0 x22: 00000000ffffffea x21: ffff8000891ac9a0
x20: ffff8000891ac9a0 x19: ffff80008afc2480 x18: 00000000ffffffff
x17: 0000000000000000 x16: ffff80008ae642c8 x15: ffff700011ede14c
x14: 1ffff00011ede14c x13: 0000000000000004 x12: ffffffffffffffff
x11: ffff700011ede14c x10: 0000000000ff0100 x9 : 5fa3c1ffaf0ff000
x8 : 5fa3c1ffaf0ff000 x7 : 0000000000000001 x6 : 0000000000000001
x5 : ffff8000a03a7078 x4 : ffff80008f766c20 x3 : ffff80008054d360
x2 : 0000000000000000 x1 : 0000000000000201 x0 : 0000000000000000
Call 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
[1]:
Unable to handle kernel write to read-only memory at virtual address ffff8000891ac9a8
KASAN: probably user-memory-access in range [0x0000000448d64d40-0x0000000448d64d47]
Mem abort info:
ESR = 0x000000009600004e
EC = 0x25: DABT (current EL), IL = 32 bits
SET = 0, FnV = 0
EA = 0, S1PTW = 0
FSC = 0x0e: level 2 permission fault
Data abort info:
ISV = 0, ISS = 0x0000004e, ISS2 = 0x00000000
CM = 0, WnR = 1, TnD = 0, TagAccess = 0
GCS = 0, Overlay = 0, DirtyBit = 0, Xs = 0
swapper pgtable: 4k pages, 48-bit VAs, pgdp=0000000207144000
[ffff8000891ac9a8] pgd=0000000000000000, p4d=100000020f950003, pud=100000020f951003, pmd=0040000201000781
Internal error: Oops: 000000009600004e [#1 ] SMP
Modules linked in:
CPU: 0 UID: 0 PID: 6946 Comm: syz.0.69 Not tainted 6.16.0-rc4-syzkaller-g7482bb149b9f #0 PREEMPT
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025
pstate: 604000c5 (nZCv daIF +PAN -UAO -TCO -DIT -SSBS BTYPE=--)
pc : kvfree_call_rcu+0x31c/0x3f0 mm/slab_common.c:1971
lr : add_ptr_to_bulk_krc_lock mm/slab_common.c:1838 [inline]
lr : kvfree_call_rcu+0xfc/0x3f0 mm/slab_common.c:1963
sp : ffff8000a28a7730
x29: ffff8000a28a7730 x28: 00000000fffffff5 x27: 1fffe00018b09bb3
x26: 0000000000000001 x25: ffff80008f66e000 x24: ffff00019beaf498
x23: ffff00019beaf4c0 x22: 0000000000000000 x21: ffff8000891ac9a0
x20: ffff8000891ac9a0 x19: 0000000000000000 x18: 00000000ffffffff
x17: ffff800093363000 x16: ffff80008052c6e4 x15: ffff700014514ecc
x14: 1ffff00014514ecc x13: 0000000000000004 x12: ffffffffffffffff
x11: ffff700014514ecc x10: 0000000000000001 x9 : 0000000000000001
x8 : ffff00019beaf7b4 x7 : ffff800080a94154 x6 : 0000000000000000
x5 : ffff8000935efa60 x4 : 0000000000000008 x3 : ffff80008052c7fc
x2 : 0000000000000001 x1 : ffff8000891ac9a0 x0 : 0000000000000001
Call trace:
kvfree_call_rcu+0x31c/0x3f0 mm/slab_common.c:1967 (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
Code: aa1f03e2 52800023 97ee1e8d b4000195 (f90006b4)
Fixes: d25a92ccaesyzbot+40bf00346c3fe40f90f2@syzkaller.appspotmail.com
Closes: https://lore.kernel.org/all/686d9b50.050a0220.1ffab7.0020.GAE@google.com/
Tested-by: syzbot+40bf00346c3fe40f90f2@syzkaller.appspotmail.com
Reported-by: syzbot+f22031fad6cbe52c70e7@syzkaller.appspotmail.com
Closes: https://lore.kernel.org/all/686da0f3.050a0220.1ffab7.0022.GAE@google.com/
Reported-by: syzbot+271fed3ed6f24600c364@syzkaller.appspotmail.com
Closes: https://syzkaller.appspot.com/bug?extid=271fed3ed6f24600c364 # [2]
Link: https://lore.kernel.org/netdev/99f284be-bf1d-4bc4-a629-77b268522fff@huawei.com/ # [3]
Link: https://lore.kernel.org/netdev/20250331081003.1503211-1-wangliang74@huawei.com/ # [4]
Signed-off-by: Kuniyuki Iwashima <kuniyu@google.com>
Reviewed-by: D. Wythe <alibuda@linux.alibaba.com>
Reviewed-by: Wang Liang <wangliang74@huawei.com>
Link: https://patch.msgid.link/20250711060808.2977529-1-kuniyu@google.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
60ada4fe64