CVE-2025-38037

In the Linux kernel, the following vulnerability has been resolved:<br /> <br /> vxlan: Annotate FDB data races<br /> <br /> The &amp;#39;used&amp;#39; and &amp;#39;updated&amp;#39; fields in the FDB entry structure can be<br /> accessed concurrently by multiple threads, leading to reports such as<br /> [1]. Can be reproduced using [2].<br /> <br /> Suppress these reports by annotating these accesses using<br /> READ_ONCE() / WRITE_ONCE().<br /> <br /> [1]<br /> BUG: KCSAN: data-race in vxlan_xmit / vxlan_xmit<br /> <br /> write to 0xffff942604d263a8 of 8 bytes by task 286 on cpu 0:<br /> vxlan_xmit+0xb29/0x2380<br /> dev_hard_start_xmit+0x84/0x2f0<br /> __dev_queue_xmit+0x45a/0x1650<br /> packet_xmit+0x100/0x150<br /> packet_sendmsg+0x2114/0x2ac0<br /> __sys_sendto+0x318/0x330<br /> __x64_sys_sendto+0x76/0x90<br /> x64_sys_call+0x14e8/0x1c00<br /> do_syscall_64+0x9e/0x1a0<br /> entry_SYSCALL_64_after_hwframe+0x77/0x7f<br /> <br /> read to 0xffff942604d263a8 of 8 bytes by task 287 on cpu 2:<br /> vxlan_xmit+0xadf/0x2380<br /> dev_hard_start_xmit+0x84/0x2f0<br /> __dev_queue_xmit+0x45a/0x1650<br /> packet_xmit+0x100/0x150<br /> packet_sendmsg+0x2114/0x2ac0<br /> __sys_sendto+0x318/0x330<br /> __x64_sys_sendto+0x76/0x90<br /> x64_sys_call+0x14e8/0x1c00<br /> do_syscall_64+0x9e/0x1a0<br /> entry_SYSCALL_64_after_hwframe+0x77/0x7f<br /> <br /> value changed: 0x00000000fffbac6e -&gt; 0x00000000fffbac6f<br /> <br /> Reported by Kernel Concurrency Sanitizer on:<br /> CPU: 2 UID: 0 PID: 287 Comm: mausezahn Not tainted 6.13.0-rc7-01544-gb4b270f11a02 #5<br /> Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.16.3-3.fc41 04/01/2014<br /> <br /> [2]<br /> #!/bin/bash<br /> <br /> set +H<br /> echo whitelist &gt; /sys/kernel/debug/kcsan<br /> echo !vxlan_xmit &gt; /sys/kernel/debug/kcsan<br /> <br /> ip link add name vx0 up type vxlan id 10010 dstport 4789 local 192.0.2.1<br /> bridge fdb add 00:11:22:33:44:55 dev vx0 self static dst 198.51.100.1<br /> taskset -c 0 mausezahn vx0 -a own -b 00:11:22:33:44:55 -c 0 -q &amp;<br /> taskset -c 2 mausezahn vx0 -a own -b 00:11:22:33:44:55 -c 0 -q &amp;