Description
In the Linux kernel, the following vulnerability has been resolved: mptcp: fix NULL pointer in can_accept_new_subflow When testing valkey benchmark tool with MPTCP, the kernel panics in 'mptcp_can_accept_new_subflow' because subflow_req->msk is NULL. Call trace: mptcp_can_accept_new_subflow (./net/mptcp/subflow.c:63 (discriminator 4)) (P) subflow_syn_recv_sock (./net/mptcp/subflow.c:854) tcp_check_req (./net/ipv4/tcp_minisocks.c:863) tcp_v4_rcv (./net/ipv4/tcp_ipv4.c:2268) ip_protocol_deliver_rcu (./net/ipv4/ip_input.c:207) ip_local_deliver_finish (./net/ipv4/ip_input.c:234) ip_local_deliver (./net/ipv4/ip_input.c:254) ip_rcv_finish (./net/ipv4/ip_input.c:449) ... According to the debug log, the same req received two SYN-ACK in a very short time, very likely because the client retransmits the syn ack due to multiple reasons. Even if the packets are transmitted with a relevant time interval, they can be processed by the server on different CPUs concurrently). The 'subflow_req->msk' ownership is transferred to the subflow the first, and there will be a risk of a null pointer dereference here. This patch fixes this issue by moving the 'subflow_req->msk' under the `own_req == true` conditional. Note that the !msk check in subflow_hmac_valid() can be dropped, because the same check already exists under the own_req mpj branch where the code has been moved to.
Affected products
Version statuses are supplied by the assigning organization. Consult the original record for detailed ranges and platform conditions.
Linux Linux
Default version status: unaffected
9466a1ccebbe54ac57fb8a89c2b4b854826546a8 to < 8cf7fef1bb2ffea7792bcbf71ca00216cecc725daffected9466a1ccebbe54ac57fb8a89c2b4b854826546a8 to < b3088bd2a6790c8efff139d86d7a9d0b1305977baffected9466a1ccebbe54ac57fb8a89c2b4b854826546a8 to < 855bf0aacd51fced11ea9aa0d5101ee0febaeadbaffected9466a1ccebbe54ac57fb8a89c2b4b854826546a8 to < 7f9ae060ed64aef8f174c5f1ea513825b1be9af1affected9466a1ccebbe54ac57fb8a89c2b4b854826546a8 to < dc81e41a307df523072186b241fa8244fecd7803affected9466a1ccebbe54ac57fb8a89c2b4b854826546a8 to < efd58a8dd9e7a709a90ee486a4247c923d27296faffected9466a1ccebbe54ac57fb8a89c2b4b854826546a8 to < 4b2649b9717678aeb097893cc49f59311a1ecab0affected9466a1ccebbe54ac57fb8a89c2b4b854826546a8 to < 443041deb5ef6a1289a99ed95015ec7442f141dcaffected
Linux Linux
Default version status: affected
5.9affected0 to < 5.9unaffected5.10.237 to ≤ 5.10.*unaffected5.15.181 to ≤ 5.15.*unaffected6.1.135 to ≤ 6.1.*unaffected6.6.88 to ≤ 6.6.*unaffected6.12.24 to ≤ 6.12.*unaffected6.13.12 to ≤ 6.13.*unaffected6.14.3 to ≤ 6.14.*unaffected6.15 to ≤ *unaffected
References
- https://git.kernel.org/stable/c/8cf7fef1bb2ffea7792bcbf71ca00216cecc725d ↗
- https://git.kernel.org/stable/c/b3088bd2a6790c8efff139d86d7a9d0b1305977b ↗
- https://git.kernel.org/stable/c/855bf0aacd51fced11ea9aa0d5101ee0febaeadb ↗
- https://git.kernel.org/stable/c/7f9ae060ed64aef8f174c5f1ea513825b1be9af1 ↗
- https://git.kernel.org/stable/c/dc81e41a307df523072186b241fa8244fecd7803 ↗
- https://git.kernel.org/stable/c/efd58a8dd9e7a709a90ee486a4247c923d27296f ↗
- https://git.kernel.org/stable/c/4b2649b9717678aeb097893cc49f59311a1ecab0 ↗
- https://git.kernel.org/stable/c/443041deb5ef6a1289a99ed95015ec7442f141dc ↗
- https://lists.debian.org/debian-lts-announce/2025/05/msg00045.html ↗
- https://lists.debian.org/debian-lts-announce/2025/05/msg00030.html ↗