Bug 2426226 (CVE-2022-50865)

Summary: CVE-2022-50865 kernel: tcp: fix a signed-integer-overflow bug in tcp_add_backlog()
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security DevOps Team <prodsec-dev>
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Priority: high    
Version: unspecifiedKeywords: Security
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OS: Linux   
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A flaw was found in the Linux kernel’s TCP implementation in the function tcp_add_backlog(). When calculating the maximum acceptable backlog for TCP sockets, the sum of the receive buffer (sk_rcvbuf), the send buffer (sk_sndbuf), and a fixed constant may exceed the maximum value of a signed integer due to both buffer values being of type int. This can result in a signed integer overflow, potentially leading to incorrect backlog limits and unexpected TCP behavior under certain workloads.
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Description OSIDB Bzimport 2025-12-30 13:17:47 UTC 
In the Linux kernel, the following vulnerability has been resolved:

tcp: fix a signed-integer-overflow bug in tcp_add_backlog()

The type of sk_rcvbuf and sk_sndbuf in struct sock is int, and
in tcp_add_backlog(), the variable limit is caculated by adding
sk_rcvbuf, sk_sndbuf and 64 * 1024, it may exceed the max value
of int and overflow. This patch reduces the limit budget by
halving the sndbuf to solve this issue since ACK packets are much
smaller than the payload.
Comment 1 Alexander B 2025-12-30 23:57:26 UTC 
Upstream advisory:
https://lore.kernel.org/linux-cve-announce/2025123049-CVE-2022-50865-281e@gregkh/T