In the Linux kernel, the following vulnerability has been resolved: net/smc: fix NULL dereference and UAF in smc_tcp_syn_recv_sock() Syzkaller reported a panic in smc_tcp_syn_recv_sock() [1]. smc_tcp_syn_recv_sock() is called in the TCP receive path (softirq) via icsk_af_ops->syn_recv_sock on the clcsock (TCP listening socket). It reads sk_user_data to get the smc_sock pointer. However, when the SMC listen socket is being closed concurrently, smc_close_active() sets clcsock->sk_user_data to NULL under sk_callback_lock, and then the smc_sock itself can be freed via sock_put() in smc_release(). This leads to two issues: 1) NULL pointer dereference: sk_user_data is NULL when accessed. 2) Use-after-free: sk_user_data is read as non-NULL, but the smc_sock is freed before its fields (e.g., queued_smc_hs, ori_af_ops) are accessed. The race window looks like this (the syzkaller crash [1] triggers via the SYN cookie path: tcp_get_cookie_sock() -> smc_tcp_syn_recv_sock(), but the normal tcp_check_req() path has the same race): CPU A (softirq) CPU B (process ctx) tcp_v4_rcv() TCP_NEW_SYN_RECV: sk = req->rsk_listener sock_hold(sk) /* No lock on listener */ smc_close_active(): write_lock_bh(cb_lock) sk_user_data = NULL write_unlock_bh(cb_lock) ... smc_clcsock_release() sock_put(smc->sk) x2 -> smc_sock freed! tcp_check_req() smc_tcp_syn_recv_sock(): smc = user_data(sk) -> NULL or dangling smc->queued_smc_hs -> crash! Note that the clcsock and smc_sock are two independent objects with separate refcounts. TCP stack holds a reference on the clcsock, which keeps it alive, but this does NOT prevent the smc_sock from being freed. Fix this by using RCU and refcount_inc_not_zero() to safely access smc_sock. Since smc_tcp_syn_recv_sock() is called in the TCP three-way handshake path, taking read_lock_bh on sk_callback_lock is too heavy and would not survive a SYN flood attack. Using rcu_read_lock() is much more lightweight. - Set SOCK_RCU_FREE on the SMC listen socket so that smc_sock freeing is deferred until after the RCU grace period. This guarantees the memory is still valid when accessed inside rcu_read_lock(). - Use rcu_read_lock() to protect reading sk_user_data. - Use refcount_inc_not_zero(&smc->sk.sk_refcnt) to pin the smc_sock. If the refcount has already reached zero (close path completed), it returns false and we bail out safely. Note: smc_hs_congested() has a similar lockless read of sk_user_data without rcu_read_lock(), but it only checks for NULL and accesses the global smc_hs_wq, never dereferencing any smc_sock field, so it is not affected. Reproducer was verified with mdelay injection and smc_run, the issue no longer occurs with this patch applied. [1] https://syzkaller.appspot.com/bug?extid=827ae2bfb3a3529333e9
In the Linux kernel, the following vulnerability has been resolved: net/smc: fix NULL dereference and UAF in smc_tcp_syn_recv_sock() Syzkaller reported a panic in smc_tcp_syn_recv_sock() [1]. smc_tcp_syn_recv_sock() is called in the TCP receive path (softirq) via icsk_af_ops->syn_recv_sock on the clcsock (TCP listening socket). It reads sk_user_data to get the smc_sock pointer. However, when the SMC listen socket is being closed concurrently, smc_close_active() sets clcsock->sk_user_data to NULL under sk_callback_lock, and then the smc_sock itself can be freed via sock_put() in smc_release(). This leads to two issues: 1) NULL pointer dereference: sk_user_data is NULL when accessed. 2) Use-after-free: sk_user_data is read as non-NULL, but the smc_sock is freed before its fields (e.g., queued_smc_hs, ori_af_ops) are accessed. The race window looks like this (the syzkaller crash [1] triggers via the SYN cookie path: tcp_get_cookie_sock() -> smc_tcp_syn_recv_sock(), but the normal tcp_check_req() path has the same race): CPU A (softirq) CPU B (process ctx) tcp_v4_rcv() TCP_NEW_SYN_RECV: sk = req->rsk_listener sock_hold(sk) /* No lock on listener */ smc_close_active(): write_lock_bh(cb_lock) sk_user_data = NULL write_unlock_bh(cb_lock) ... smc_clcsock_release() sock_put(smc->sk) x2 -> smc_sock freed! tcp_check_req() smc_tcp_syn_recv_sock(): smc = user_data(sk) -> NULL or dangling smc->queued_smc_hs -> crash! Note that the clcsock and smc_sock are two independent objects with separate refcounts. TCP stack holds a reference on the clcsock, which keeps it alive, but this does NOT prevent the smc_sock from being freed. Fix this by using RCU and refcount_inc_not_zero() to safely access smc_sock. Since smc_tcp_syn_recv_sock() is called in the TCP three-way handshake path, taking read_lock_bh on sk_callback_lock is too heavy and would not survive a SYN flood attack. Using rcu_read_lock() is much more lightweight. - Set SOCK_RCU_FREE on the SMC listen socket so that smc_sock freeing is deferred until after the RCU grace period. This guarantees the memory is still valid when accessed inside rcu_read_lock(). - Use rcu_read_lock() to protect reading sk_user_data. - Use refcount_inc_not_zero(&smc->sk.sk_refcnt) to pin the smc_sock. If the refcount has already reached zero (close path completed), it returns false and we bail out safely. Note: smc_hs_congested() has a similar lockless read of sk_user_data without rcu_read_lock(), but it only checks for NULL and accesses the global smc_hs_wq, never dereferencing any smc_sock field, so it is not affected. Reproducer was verified with mdelay injection and smc_run, the issue no longer occurs with this patch applied. [1] https://syzkaller.appspot.com/bug?extid=827ae2bfb3a3529333e9
Update Linux/Linux to f315277856caeafcd996c2611afc085ca2d53275; Siemens/SIMATIC S7-1500 CPU 1518-4 PN/DP MFP to *; Siemens/SIMATIC S7-1500 CPU 1518-4 PN/DP MFP to *; Siemens/SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP to *; Siemens/SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP to *; Siemens/SIPLUS S7-1500 CPU 1518-4 PN/DP MFP to *; Siemens/SIPLUS S7-1500 CPU 1518-4 PN/DP MFP to * if you use the affected versions. Test the change in a non-production environment first.
Local check
hol-guard supply-chain scannet/smc: fix NULL dereference and UAF in smc_tcp_syn_recv_sock() affects Linux/Linux (generic), Linux/Linux (generic), Siemens/SIMATIC S7-1500 CPU 1518-4 PN/DP MFP (generic), Siemens/SIMATIC S7-1500 CPU 1518-4 PN/DP MFP (generic), Siemens/SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP (generic), Siemens/SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP (generic), Siemens/SIPLUS S7-1500 CPU 1518-4 PN/DP MFP (generic), Siemens/SIPLUS S7-1500 CPU 1518-4 PN/DP MFP (generic). Severity is critical. In the Linux kernel, the following vulnerability has been resolved: net/smc: fix NULL dereference and UAF in smc_tcp_syn_recv_sock() Syzkaller reported a panic in smc_tcp_syn_recv_sock() [1]. smc_tcp_syn_recv_sock() is called in the TCP receive path (softirq) via icsk_af_ops->syn_recv_sock on the clcsock (TCP listening socket). It reads sk_user_data to get the smc_sock pointer. However, when the SMC listen socket is being closed concurrently, smc_close_active() sets clcsock->sk_user_data to NULL under sk_callback_lock, and then the smc_sock itself can be freed via sock_put() in smc_release(). This leads to two issues: 1) NULL pointer dereference: sk_user_data is NULL when accessed. 2) Use-after-free: sk_user_data is read as non-NULL, but the smc_sock is freed before its fields (e.g., queued_smc_hs, ori_af_ops) are accessed. The race window looks like this (the syzkaller crash [1] triggers via the SYN cookie path: tcp_get_cookie_sock() -> smc_tcp_syn_recv_sock(), but the normal tcp_check_req() path has the same race): CPU A (softirq) CPU B (process ctx) tcp_v4_rcv() TCP_NEW_SYN_RECV: sk = req->rsk_listener sock_hold(sk) /* No lock on listener */ smc_close_active(): write_lock_bh(cb_lock) sk_user_data = NULL write_unlock_bh(cb_lock) ... smc_clcsock_release() sock_put(smc->sk) x2 -> smc_sock freed! tcp_check_req() smc_tcp_syn_recv_sock(): smc = user_data(sk) -> NULL or dangling smc->queued_smc_hs -> crash! Note that the clcsock and smc_sock are two independent objects with separate refcounts. TCP stack holds a reference on the clcsock, which keeps it alive, but this does NOT prevent the smc_sock from being freed. Fix this by using RCU and refcount_inc_not_zero() to safely access smc_sock. Since smc_tcp_syn_recv_sock() is called in the TCP three-way handshake path, taking read_lock_bh on sk_callback_lock is too heavy and would not survive a SYN flood attack. Using rcu_read_lock() is much more lightweight. - Set SOCK_RCU_FREE on the SMC listen socket so that smc_sock freeing is deferred until after the RCU grace period. This guarantees the memory is still valid when accessed inside rcu_read_lock(). - Use rcu_read_lock() to protect reading sk_user_data. - Use refcount_inc_not_zero(&smc->sk.sk_refcnt) to pin the smc_sock. If the refcount has already reached zero (close path completed), it returns false and we bail out safely. Note: smc_hs_congested() has a similar lockless read of sk_user_data without rcu_read_lock(), but it only checks for NULL and accesses the global smc_hs_wq, never dereferencing any smc_sock field, so it is not affected. Reproducer was verified with mdelay injection and smc_run, the issue no longer occurs with this patch applied. [1] https://syzkaller.appspot.com/bug?extid=827ae2bfb3a3529333e9
AI coding agents often install or upgrade packages automatically in generic. A critical vulnerability in a dependency can be pulled into a project through a normal install or update without a human reviewing the change, expanding the blast radius from a single package to every agent workspace that depends on it.
| Package | Affected range | Fixed version |
|---|---|---|
| Linux/Linuxgeneric | >=ebfee3e153f67c8b38eb94a7062ee94aa6f92708 <f315277856caeafcd996c2611afc085ca2d53275 || >=8270d9c21041470f58348248b9d9dcf3bf79592e <1e4f873879e075bbd4eb1c644d6933303ac5eba4 || >=8270d9c21041470f58348248b9d9dcf3bf79592e <f00fc26c8a06442b225a350fe000c0a11483e6a3 || >=8270d9c21041470f58348248b9d9dcf3bf79592e <cadf3da46c15523fba90d80c9955f536ee3b4023 || >=8270d9c21041470f58348248b9d9dcf3bf79592e <fd7579f0a2c84ba8a7d4f206201b50dc8ddf90c2 || >=8270d9c21041470f58348248b9d9dcf3bf79592e <1fab5ece76fb42a761178dcd0ebcbf578377b0dd || >=8270d9c21041470f58348248b9d9dcf3bf79592e <6d5e4538364b9ceb1ac2941a4deb86650afb3538 || >=5.15.174 <5.15.203 | f315277856caeafcd996c2611afc085ca2d53275, 1e4f873879e075bbd4eb1c644d6933303ac5eba4, f00fc26c8a06442b225a350fe000c0a11483e6a3, cadf3da46c15523fba90d80c9955f536ee3b4023, fd7579f0a2c84ba8a7d4f206201b50dc8ddf90c2, 1fab5ece76fb42a761178dcd0ebcbf578377b0dd, 6d5e4538364b9ceb1ac2941a4deb86650afb3538, 5.15.203 |
| Linux/Linuxgeneric | 5.18 | Not reported |
| Siemens/SIMATIC S7-1500 CPU 1518-4 PN/DP MFPgeneric | >=V3.1.6 <* | * |
| Siemens/SIMATIC S7-1500 CPU 1518-4 PN/DP MFPgeneric | >=V3.1.5 <* | * |
Reported by CVE List V5 (cvelist).
HOL Guard can help your team review package activity against supported protection paths.
Explore HOL GuardUpdate Linux/Linux to f315277856caeafcd996c2611afc085ca2d53275; Siemens/SIMATIC S7-1500 CPU 1518-4 PN/DP MFP to *; Siemens/SIMATIC S7-1500 CPU 1518-4 PN/DP MFP to *; Siemens/SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP to *; Siemens/SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP to *; Siemens/SIPLUS S7-1500 CPU 1518-4 PN/DP MFP to *; Siemens/SIPLUS S7-1500 CPU 1518-4 PN/DP MFP to * if you use the affected versions. Test the change in a non-production environment first.
Local check
hol-guard supply-chain scannet/smc: fix NULL dereference and UAF in smc_tcp_syn_recv_sock() affects Linux/Linux (generic), Linux/Linux (generic), Siemens/SIMATIC S7-1500 CPU 1518-4 PN/DP MFP (generic), Siemens/SIMATIC S7-1500 CPU 1518-4 PN/DP MFP (generic), Siemens/SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP (generic), Siemens/SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP (generic), Siemens/SIPLUS S7-1500 CPU 1518-4 PN/DP MFP (generic), Siemens/SIPLUS S7-1500 CPU 1518-4 PN/DP MFP (generic). Severity is critical. In the Linux kernel, the following vulnerability has been resolved: net/smc: fix NULL dereference and UAF in smc_tcp_syn_recv_sock() Syzkaller reported a panic in smc_tcp_syn_recv_sock() [1]. smc_tcp_syn_recv_sock() is called in the TCP receive path (softirq) via icsk_af_ops->syn_recv_sock on the clcsock (TCP listening socket). It reads sk_user_data to get the smc_sock pointer. However, when the SMC listen socket is being closed concurrently, smc_close_active() sets clcsock->sk_user_data to NULL under sk_callback_lock, and then the smc_sock itself can be freed via sock_put() in smc_release(). This leads to two issues: 1) NULL pointer dereference: sk_user_data is NULL when accessed. 2) Use-after-free: sk_user_data is read as non-NULL, but the smc_sock is freed before its fields (e.g., queued_smc_hs, ori_af_ops) are accessed. The race window looks like this (the syzkaller crash [1] triggers via the SYN cookie path: tcp_get_cookie_sock() -> smc_tcp_syn_recv_sock(), but the normal tcp_check_req() path has the same race): CPU A (softirq) CPU B (process ctx) tcp_v4_rcv() TCP_NEW_SYN_RECV: sk = req->rsk_listener sock_hold(sk) /* No lock on listener */ smc_close_active(): write_lock_bh(cb_lock) sk_user_data = NULL write_unlock_bh(cb_lock) ... smc_clcsock_release() sock_put(smc->sk) x2 -> smc_sock freed! tcp_check_req() smc_tcp_syn_recv_sock(): smc = user_data(sk) -> NULL or dangling smc->queued_smc_hs -> crash! Note that the clcsock and smc_sock are two independent objects with separate refcounts. TCP stack holds a reference on the clcsock, which keeps it alive, but this does NOT prevent the smc_sock from being freed. Fix this by using RCU and refcount_inc_not_zero() to safely access smc_sock. Since smc_tcp_syn_recv_sock() is called in the TCP three-way handshake path, taking read_lock_bh on sk_callback_lock is too heavy and would not survive a SYN flood attack. Using rcu_read_lock() is much more lightweight. - Set SOCK_RCU_FREE on the SMC listen socket so that smc_sock freeing is deferred until after the RCU grace period. This guarantees the memory is still valid when accessed inside rcu_read_lock(). - Use rcu_read_lock() to protect reading sk_user_data. - Use refcount_inc_not_zero(&smc->sk.sk_refcnt) to pin the smc_sock. If the refcount has already reached zero (close path completed), it returns false and we bail out safely. Note: smc_hs_congested() has a similar lockless read of sk_user_data without rcu_read_lock(), but it only checks for NULL and accesses the global smc_hs_wq, never dereferencing any smc_sock field, so it is not affected. Reproducer was verified with mdelay injection and smc_run, the issue no longer occurs with this patch applied. [1] https://syzkaller.appspot.com/bug?extid=827ae2bfb3a3529333e9
AI coding agents often install or upgrade packages automatically in generic. A critical vulnerability in a dependency can be pulled into a project through a normal install or update without a human reviewing the change, expanding the blast radius from a single package to every agent workspace that depends on it.
| Package | Affected range | Fixed version |
|---|---|---|
| Linux/Linuxgeneric | >=ebfee3e153f67c8b38eb94a7062ee94aa6f92708 <f315277856caeafcd996c2611afc085ca2d53275 || >=8270d9c21041470f58348248b9d9dcf3bf79592e <1e4f873879e075bbd4eb1c644d6933303ac5eba4 || >=8270d9c21041470f58348248b9d9dcf3bf79592e <f00fc26c8a06442b225a350fe000c0a11483e6a3 || >=8270d9c21041470f58348248b9d9dcf3bf79592e <cadf3da46c15523fba90d80c9955f536ee3b4023 || >=8270d9c21041470f58348248b9d9dcf3bf79592e <fd7579f0a2c84ba8a7d4f206201b50dc8ddf90c2 || >=8270d9c21041470f58348248b9d9dcf3bf79592e <1fab5ece76fb42a761178dcd0ebcbf578377b0dd || >=8270d9c21041470f58348248b9d9dcf3bf79592e <6d5e4538364b9ceb1ac2941a4deb86650afb3538 || >=5.15.174 <5.15.203 | f315277856caeafcd996c2611afc085ca2d53275, 1e4f873879e075bbd4eb1c644d6933303ac5eba4, f00fc26c8a06442b225a350fe000c0a11483e6a3, cadf3da46c15523fba90d80c9955f536ee3b4023, fd7579f0a2c84ba8a7d4f206201b50dc8ddf90c2, 1fab5ece76fb42a761178dcd0ebcbf578377b0dd, 6d5e4538364b9ceb1ac2941a4deb86650afb3538, 5.15.203 |
| Linux/Linuxgeneric | 5.18 | Not reported |
| Siemens/SIMATIC S7-1500 CPU 1518-4 PN/DP MFPgeneric | >=V3.1.6 <* | * |
| Siemens/SIMATIC S7-1500 CPU 1518-4 PN/DP MFPgeneric | >=V3.1.5 <* | * |
Reported by CVE List V5 (cvelist).
HOL Guard can help your team review package activity against supported protection paths.
Explore HOL Guard| Siemens/SIMATIC S7-1500 CPU 1518F-4 PN/DP MFPgeneric |
|---|
| >=V3.1.6 <* |
| * |
| Siemens/SIMATIC S7-1500 CPU 1518F-4 PN/DP MFPgeneric | >=V3.1.5 <* | * |
|---|
| Siemens/SIPLUS S7-1500 CPU 1518-4 PN/DP MFPgeneric | >=V3.1.6 <* | * |
|---|
| Siemens/SIPLUS S7-1500 CPU 1518-4 PN/DP MFPgeneric | >=V3.1.5 <* | * |
|---|
Fixed versions are reported by the source feed; confirm compatibility before updating.
| Siemens/SIMATIC S7-1500 CPU 1518F-4 PN/DP MFPgeneric |
|---|
| >=V3.1.6 <* |
| * |
| Siemens/SIMATIC S7-1500 CPU 1518F-4 PN/DP MFPgeneric | >=V3.1.5 <* | * |
|---|
| Siemens/SIPLUS S7-1500 CPU 1518-4 PN/DP MFPgeneric | >=V3.1.6 <* | * |
|---|
| Siemens/SIPLUS S7-1500 CPU 1518-4 PN/DP MFPgeneric | >=V3.1.5 <* | * |
|---|
Fixed versions are reported by the source feed; confirm compatibility before updating.