Re: [PATCH net,v3] net/smc: prevent NULL pointer dereference in txopt_get

"D. Wythe" <alibuda@xxxxxxxxxxxxxxxxx> · Wed, 14 Aug 2024 10:42:47 +0800

On 8/14/24 10:25 AM, D. Wythe wrote:


On 8/13/24 7:48 PM, Jeongjun Park wrote:
D. Wythe wrote:


On 8/13/24 6:07 PM, Jeongjun Park wrote:
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.

Reported-by: syzbot+f69bfae0a4eb29976e44@xxxxxxxxxxxxxxxxxxxxxxxxx
Tested-by: syzbot+f69bfae0a4eb29976e44@xxxxxxxxxxxxxxxxxxxxxxxxx
Fixes: d25a92ccae6b ("net/smc: Introduce IPPROTO_SMC")
Signed-off-by: Jeongjun Park <aha310510@xxxxxxxxx>
---
   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..25f34fd65e8d 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;
+};
I prefer to:

struct ipv6_pinfo inet6;
Okay, I'll write a v4 patch and send it to you tomorrow.

Regards,
Jeongjun Park

Before you issue the v4, I still don't know why you move clcsk_xxx 
from smc_connection
to smc_sock, can you explain it ?


I misread it, it seems you're moving them from head to tail, but still, 
the same question,
why move it ?

Thanks
D. Wythe



Also, regarding alignment, it's okay for me whether it's aligned or 
not，But I checked the styles of other types of
structures and did not strictly require alignment, so I now feel that 
there is no need to
modify so much to do alignment.

D. Wythe





+
   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 = {
--









