CVE-2023-53382
Unknown Unknown - Not Provided
BaseFortify

Publication date: 2025-09-18

Last updated on: 2025-12-11

Assigner: kernel.org

Description
In the Linux kernel, the following vulnerability has been resolved: net/smc: Reset connection when trying to use SMCRv2 fails. We found a crash when using SMCRv2 with 2 Mellanox ConnectX-4. It can be reproduced by: - smc_run nginx - smc_run wrk -t 32 -c 500 -d 30 http://<ip>:<port> BUG: kernel NULL pointer dereference, address: 0000000000000014 #PF: supervisor read access in kernel mode #PF: error_code(0x0000) - not-present page PGD 8000000108713067 P4D 8000000108713067 PUD 151127067 PMD 0 Oops: 0000 [#1] PREEMPT SMP PTI CPU: 4 PID: 2441 Comm: kworker/4:249 Kdump: loaded Tainted: G W E 6.4.0-rc1+ #42 Workqueue: smc_hs_wq smc_listen_work [smc] RIP: 0010:smc_clc_send_confirm_accept+0x284/0x580 [smc] RSP: 0018:ffffb8294b2d7c78 EFLAGS: 00010a06 RAX: ffff8f1873238880 RBX: ffffb8294b2d7dc8 RCX: 0000000000000000 RDX: 00000000000000b4 RSI: 0000000000000001 RDI: 0000000000b40c00 RBP: ffffb8294b2d7db8 R08: ffff8f1815c5860c R09: 0000000000000000 R10: 0000000000000400 R11: 0000000000000000 R12: ffff8f1846f56180 R13: ffff8f1815c5860c R14: 0000000000000001 R15: 0000000000000001 FS: 0000000000000000(0000) GS:ffff8f1aefd00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000000000000014 CR3: 00000001027a0001 CR4: 00000000003706e0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: <TASK> ? mlx5_ib_map_mr_sg+0xa1/0xd0 [mlx5_ib] ? smcr_buf_map_link+0x24b/0x290 [smc] ? __smc_buf_create+0x4ee/0x9b0 [smc] smc_clc_send_accept+0x4c/0xb0 [smc] smc_listen_work+0x346/0x650 [smc] ? __schedule+0x279/0x820 process_one_work+0x1e5/0x3f0 worker_thread+0x4d/0x2f0 ? __pfx_worker_thread+0x10/0x10 kthread+0xe5/0x120 ? __pfx_kthread+0x10/0x10 ret_from_fork+0x2c/0x50 </TASK> During the CLC handshake, server sequentially tries available SMCRv2 and SMCRv1 devices in smc_listen_work(). If an SMCRv2 device is found. SMCv2 based link group and link will be assigned to the connection. Then assumed that some buffer assignment errors happen later in the CLC handshake, such as RMB registration failure, server will give up SMCRv2 and try SMCRv1 device instead. But the resources assigned to the connection won't be reset. When server tries SMCRv1 device, the connection creation process will be executed again. Since conn->lnk has been assigned when trying SMCRv2, it will not be set to the correct SMCRv1 link in smcr_lgr_conn_assign_link(). So in such situation, conn->lgr points to correct SMCRv1 link group but conn->lnk points to the SMCRv2 link mistakenly. Then in smc_clc_send_confirm_accept(), conn->rmb_desc->mr[link->link_idx] will be accessed. Since the link->link_idx is not correct, the related MR may not have been initialized, so crash happens. | Try SMCRv2 device first | |-> conn->lgr: assign existed SMCRv2 link group; | |-> conn->link: assign existed SMCRv2 link (link_idx may be 1 in SMC_LGR_SYMMETRIC); | |-> sndbuf & RMB creation fails, quit; | | Try SMCRv1 device then | |-> conn->lgr: create SMCRv1 link group and assign; | |-> conn->link: keep SMCRv2 link mistakenly; | |-> sndbuf & RMB creation succeed, only RMB->mr[link_idx = 0] | initialized. | | Then smc_clc_send_confirm_accept() accesses | conn->rmb_desc->mr[conn->link->link_idx, which is 1], then crash. v This patch tries to fix this by cleaning conn->lnk before assigning link. In addition, it is better to reset the connection and clean the resources assigned if trying SMCRv2 failed in buffer creation or registration.
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Meta Information
Published
2025-09-18
Last Modified
2025-12-11
Generated
2026-05-27
AI Q&A
2025-09-18
EPSS Evaluated
2026-05-25
NVD
CVE-2023-53382
Affected Vendors & Products
Showing 5 associated CPEs
Vendor Product Version / Range
linux linux_kernel From 5.16 (inc) to 6.1.31 (exc)
linux linux_kernel From 6.2 (inc) to 6.3.5 (exc)
linux linux_kernel 6.4
linux linux_kernel 6.4
linux linux_kernel 6.4
Helpful Resources
Exploitability
CWE
CWE Icon
KEV
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CWE ID Description
CWE-476 The product dereferences a pointer that it expects to be valid but is NULL.
Attack-Flow Graph
AI Powered Q&A
Can you explain this vulnerability to me?

This vulnerability occurs in the Linux kernel's SMC (Shared Memory Communications) subsystem when using SMCRv2 devices. During the connection setup, if the server tries to use an SMCRv2 device and fails in buffer creation or registration, it falls back to an SMCRv1 device but does not properly reset the connection's link resource. This causes a mismatch where the connection's link group points to the SMCRv1 device but the link still points to the SMCRv2 device. Later, when the kernel tries to access memory related to the SMCRv2 link, it accesses uninitialized memory, leading to a NULL pointer dereference and kernel crash.


How can this vulnerability impact me? :

This vulnerability can cause a kernel crash (NULL pointer dereference) when using SMCRv2 devices in certain network communication scenarios. This crash can lead to system instability, denial of service, and potential disruption of network services relying on the SMC subsystem.


How can this vulnerability be detected on my network or system? Can you suggest some commands?

This vulnerability can be detected by reproducing the crash scenario described: running smc_run with nginx and wrk commands to trigger the SMCRv2 usage. Specifically, you can run the following commands to test for the issue: - smc_run nginx - smc_run wrk -t 32 -c 500 -d 30 http://<ip>:<port> If the system crashes with a kernel NULL pointer dereference related to smc_clc_send_confirm_accept, it indicates the vulnerability is present.


What immediate steps should I take to mitigate this vulnerability?

Immediate mitigation steps include applying the patch that resets the connection and cleans resources when SMCRv2 buffer creation or registration fails. This patch fixes the issue by cleaning the connection link before assigning a new link and resetting the connection to avoid crashes. Until patched, avoid using SMCRv2 devices in environments with Mellanox ConnectX-4 hardware or disable SMCRv2 to prevent triggering the bug.


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