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CVE-2026-99139unknown

tcp: fix use-after-free in do_tcp_getsockopt(TCP_CONGESTION)

Impact

In the Linux kernel, the following vulnerability has been resolved:

Source excerpt · Linux

Affected packages

This source has no supported package-version data for matching. You can read the advisory here, but this record alone cannot power a dependency check.

Affected products

Vendor version evidence. Product records are separate from automatic dependency matching.

Linux · Linux

Other versions: unaffected

Version / rangeSource status
0baf26b0fcd74bbfcef53c5d5e8bad2b99c8d0d2 to before c1804ef016392dd91267d2207ee43b1de34302caaffected
0baf26b0fcd74bbfcef53c5d5e8bad2b99c8d0d2 to before a8e45471afa230c1431c26c8e99ec24377e3b514affected
0baf26b0fcd74bbfcef53c5d5e8bad2b99c8d0d2 to before 5271b79b7ad68dcb222e893773f92bdabf7750f3affected
Linux version evidence

Linux · Linux

Other versions: affected

Version / rangeSource status
5.6affected
0 to before 5.6unaffected
6.18.59 through 6.18.* (inclusive)unaffected
7.2.13 through 7.2.* (inclusive)unaffected
7.3 through * (inclusive)unaffected
Linux version evidence

Original source description

In the Linux kernel, the following vulnerability has been resolved:

tcp: fix use-after-free in do_tcp_getsockopt(TCP_CONGESTION)

do_tcp_getsockopt() reads icsk->icsk_ca_ops->name without holding rcu_read_lock(). Since commit 0baf26b0fcd7 ("bpf: tcp: Support tcp_congestion_ops in bpf"), icsk_ca_ops can point to dynamically allocated BPF struct_ops memory that may be freed concurrently via setsockopt(TCP_CONGESTION), leading to a use-after-free.

BUG: KASAN: slab-use-after-free in _copy_to_user+0x37/0x60 Read of size 16 at addr ffff888013505260 by task exploit/149 _copy_to_user+0x37/0x60 do_tcp_getsockopt+0x158a/0x2460 (net/ipv4/tcp.c:4585) tcp_getsockopt+0x91/0xf0 __sys_getsockopt+0xf7/0x170

Fix this by holding rcu_read_lock() around the ca_ops->name access, using READ_ONCE() to load icsk_ca_ops, and copying the name to a stack buffer before releasing the lock. Also annotate the relevant icsk_ca_ops stores with WRITE_ONCE() to fix the accompanying KCSAN data-race issue.

References