[PATCH net] net/smc: prevent NULL pointer dereference in txopt_get

Jeongjun Park
2024-08-10T17:23:07Z

Since smc_inet6_prot does not initialize ipv6_pinfo_offset, inet6_create()
copies an incorrect address value, sk + 0 (offset), to inet_sk(sk)->pinet6.

In addition, since inet_sk(sk)->pinet6 and smc_sk(sk)->clcsock practically
point to the same address, when smc_create_clcsk() stores the newly
created clcsock in smc_sk(sk)->clcsock, inet_sk(sk)->pinet6 is corrupted
into clcsock. This causes NULL pointer dereference and various other
memory corruptions.

To solve this, we need to add a smc6_sock structure for ipv6_pinfo_offset
initialization and modify the smc_sock structure.

[ 278.629552][T28696] ==================================================================
[ 278.631367][T28696] BUG: KASAN: null-ptr-deref in txopt_get+0x102/0x430
[ 278.632724][T28696] Read of size 4 at addr 0000000000000200 by task syz.0.2965/28696
[ 278.634802][T28696]
[ 278.635236][T28696] CPU: 0 UID: 0 PID: 28696 Comm: syz.0.2965 Not tainted 6.11.0-rc2 #3
[ 278.637458][T28696] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.15.0-1 04/01/2014
[ 278.639426][T28696] Call Trace:
[ 278.639833][T28696] <TASK>
[ 278.640190][T28696] dump_stack_lvl+0x116/0x1b0
[ 278.640844][T28696] ? txopt_get+0x102/0x430
[ 278.641620][T28696] kasan_report+0xbd/0xf0
[ 278.642440][T28696] ? txopt_get+0x102/0x430
[ 278.643291][T28696] kasan_check_range+0xf4/0x1a0
[ 278.644163][T28696] txopt_get+0x102/0x430
[ 278.644940][T28696] ? __pfx_txopt_get+0x10/0x10
[ 278.645877][T28696] ? selinux_netlbl_socket_setsockopt+0x1d0/0x420
[ 278.646972][T28696] calipso_sock_getattr+0xc6/0x3e0
[ 278.647630][T28696] calipso_sock_getattr+0x4b/0x80
[ 278.648349][T28696] netlbl_sock_getattr+0x63/0xc0
[ 278.649318][T28696] selinux_netlbl_socket_setsockopt+0x1db/0x420
[ 278.650471][T28696] ? __pfx_selinux_netlbl_socket_setsockopt+0x10/0x10
[ 278.652217][T28696] ? find_held_lock+0x2d/0x120
[ 278.652231][T28696] selinux_socket_setsockopt+0x66/0x90
[ 278.652247][T28696] security_socket_setsockopt+0x57/0xb0
[ 278.652278][T28696] do_sock_setsockopt+0xf2/0x480
[ 278.652289][T28696] ? __pfx_do_sock_setsockopt+0x10/0x10
[ 278.652298][T28696] ? __fget_files+0x24b/0x4a0
[ 278.652308][T28696] ? __fget_light+0x177/0x210
[ 278.652316][T28696] __sys_setsockopt+0x1a6/0x270
[ 278.652328][T28696] ? __pfx___sys_setsockopt+0x10/0x10
[ 278.661787][T28696] ? xfd_validate_state+0x5d/0x180
[ 278.662821][T28696] __x64_sys_setsockopt+0xbd/0x160
[ 278.663719][T28696] ? lockdep_hardirqs_on+0x7c/0x110
[ 278.664690][T28696] do_syscall_64+0xcb/0x250
[ 278.665507][T28696] entry_SYSCALL_64_after_hwframe+0x77/0x7f
[ 278.666618][T28696] RIP: 0033:0x7fe87ed9712d
[ 278.667236][T28696] Code: 02 b8 ff ff ff ff c3 66 0f 1f 44 00 00 f3 0f 1e fa 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 a8 ff ff ff f7 d8 64 89 01 48
[ 278.670801][T28696] RSP: 002b:00007fe87faa4fa8 EFLAGS: 00000246 ORIG_RAX: 0000000000000036
[ 278.671832][T28696] RAX: ffffffffffffffda RBX: 00007fe87ef35f80 RCX: 00007fe87ed9712d
[ 278.672806][T28696] RDX: 0000000000000036 RSI: 0000000000000029 RDI: 0000000000000003
[ 278.674263][T28696] RBP: 00007fe87ee1bd8a R08: 0000000000000018 R09: 0000000000000000
[ 278.675967][T28696] R10: 0000000020000000 R11: 0000000000000246 R12: 0000000000000000
[ 278.677953][T28696] R13: 000000000000000b R14: 00007fe87ef35f80 R15: 00007fe87fa85000
[ 278.679321][T28696] </TASK>
[ 278.679917][T28696] ==================================================================

Fixes: d25a92ccae6b ("net/smc: Introduce IPPROTO_SMC")
Signed-off-by: Jeongjun Park <aha310510@gmail.com>
---
net/smc/smc.h | 19 ++++++++++---------
net/smc/smc_inet.c | 24 +++++++++++++++---------
2 files changed, 25 insertions(+), 18 deletions(-)

diff --git a/net/smc/smc.h b/net/smc/smc.h
index 34b781e463c4..f4d9338b5ed5 100644
--- a/net/smc/smc.h
+++ b/net/smc/smc.h
@@ -284,15 +284,6 @@ struct smc_connection {

struct smc_sock { /* smc sock container */
struct sock sk;
- struct socket *clcsock; /* internal tcp socket */
- void (*clcsk_state_change)(struct sock *sk);
- /* original stat_change fct. */
- void (*clcsk_data_ready)(struct sock *sk);
- /* original data_ready fct. */
- void (*clcsk_write_space)(struct sock *sk);
- /* original write_space fct. */
- void (*clcsk_error_report)(struct sock *sk);
- /* original error_report fct. */
struct smc_connection conn; /* smc connection */
struct smc_sock *listen_smc; /* listen parent */
struct work_struct connect_work; /* handle non-blocking connect*/
@@ -325,6 +316,16 @@ struct smc_sock { /* smc sock container */
/* protects clcsock of a listen
* socket
* */
+ struct socket *clcsock; /* internal tcp socket */
+ void (*clcsk_state_change)(struct sock *sk);
+ /* original stat_change fct. */
+ void (*clcsk_data_ready)(struct sock *sk);
+ /* original data_ready fct. */
+ void (*clcsk_write_space)(struct sock *sk);
+ /* original write_space fct. */
+ void (*clcsk_error_report)(struct sock *sk);
+ /* original error_report fct. */
+
};

#define smc_sk(ptr) container_of_const(ptr, struct smc_sock, sk)
diff --git a/net/smc/smc_inet.c b/net/smc/smc_inet.c
index bece346dd8e9..3c54faef6042 100644
--- a/net/smc/smc_inet.c
+++ b/net/smc/smc_inet.c
@@ -60,16 +60,22 @@ static struct inet_protosw smc_inet_protosw = {
};

#if IS_ENABLED(CONFIG_IPV6)
+struct smc6_sock {
+ struct smc_sock smc;
+ struct ipv6_pinfo np;
+};
+
static struct proto smc_inet6_prot = {
- .name = "INET6_SMC",
- .owner = THIS_MODULE,
- .init = smc_inet_init_sock,
- .hash = smc_hash_sk,
- .unhash = smc_unhash_sk,
- .release_cb = smc_release_cb,
- .obj_size = sizeof(struct smc_sock),
- .h.smc_hash = &smc_v6_hashinfo,
- .slab_flags = SLAB_TYPESAFE_BY_RCU,
+ .name = "INET6_SMC",
+ .owner = THIS_MODULE,
+ .init = smc_inet_init_sock,
+ .hash = smc_hash_sk,
+ .unhash = smc_unhash_sk,
+ .release_cb = smc_release_cb,
+ .obj_size = sizeof(struct smc6_sock),
+ .h.smc_hash = &smc_v6_hashinfo,
+ .slab_flags = SLAB_TYPESAFE_BY_RCU,
+ .ipv6_pinfo_offset = offsetof(struct smc6_sock, np),
};

static const struct proto_ops smc_inet6_stream_ops = {
--