In the Linux kernel, the following vulnerability has been resolved:
vxlan: Annotate FDB data races
The 'used' and 'updated' fields in the FDB entry structure can be accessed concurrently by multiple threads, leading to reports such as [1]. Can be reproduced using [2].
Suppress these reports by annotating these accesses using READONCE() / WRITEONCE().
[1] BUG: KCSAN: data-race in vxlanxmit / vxlanxmit
write to 0xffff942604d263a8 of 8 bytes by task 286 on cpu 0: vxlanxmit+0xb29/0x2380 devhardstartxmit+0x84/0x2f0 _devqueuexmit+0x45a/0x1650 packetxmit+0x100/0x150 packetsendmsg+0x2114/0x2ac0 _syssendto+0x318/0x330 _x64syssendto+0x76/0x90 x64syscall+0x14e8/0x1c00 dosyscall64+0x9e/0x1a0 entrySYSCALL64afterhwframe+0x77/0x7f
read to 0xffff942604d263a8 of 8 bytes by task 287 on cpu 2: vxlanxmit+0xadf/0x2380 devhardstartxmit+0x84/0x2f0 _devqueuexmit+0x45a/0x1650 packetxmit+0x100/0x150 packetsendmsg+0x2114/0x2ac0 _syssendto+0x318/0x330 _x64syssendto+0x76/0x90 x64syscall+0x14e8/0x1c00 dosyscall64+0x9e/0x1a0 entrySYSCALL64afterhwframe+0x77/0x7f
value changed: 0x00000000fffbac6e -> 0x00000000fffbac6f
Reported by Kernel Concurrency Sanitizer on: CPU: 2 UID: 0 PID: 287 Comm: mausezahn Not tainted 6.13.0-rc7-01544-gb4b270f11a02 #5 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.16.3-3.fc41 04/01/2014
[2] #!/bin/bash
set +H echo whitelist > /sys/kernel/debug/kcsan echo !vxlan_xmit > /sys/kernel/debug/kcsan
ip link add name vx0 up type vxlan id 10010 dstport 4789 local 192.0.2.1 bridge fdb add 00:11:22:33:44:55 dev vx0 self static dst 198.51.100.1 taskset -c 0 mausezahn vx0 -a own -b 00:11:22:33:44:55 -c 0 -q & taskset -c 2 mausezahn vx0 -a own -b 00:11:22:33:44:55 -c 0 -q &
[
    {
        "id": "CVE-2025-38037-20898608",
        "target": {
            "function": "vxlan_snoop",
            "file": "drivers/net/vxlan/vxlan_core.c"
        },
        "signature_type": "Function",
        "source": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git@a6644aeb8ddf196dec5f8e782293c36f065df4d7",
        "digest": {
            "function_hash": "284902108426095043404729802135770872898",
            "length": 1304.0
        },
        "deprecated": false,
        "signature_version": "v1"
    },
    {
        "id": "CVE-2025-38037-366e121b",
        "target": {
            "file": "drivers/net/vxlan/vxlan_core.c"
        },
        "signature_type": "Line",
        "source": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git@13cba3f837903f7184d6e9b6137d5165ffe82a8f",
        "digest": {
            "threshold": 0.9,
            "line_hashes": [
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                "92016851049059881980186999922041173476",
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                "121143068329831555142990563949026035450",
                "1547948656395481214145460225656691709",
                "227053147053905290747070094416838373648",
                "91070087258226488615892952410376555654",
                "271024820205311123893512763499513553202",
                "103868164130355074626911838203044791182",
                "139093221690187512779433414184419208701",
                "119980346355488153096297113723034375897",
                "265979125269309282450839725226671365570",
                "308881916453951564484322922134101095259",
                "209460378706944378698268287315686711329",
                "315289644549991886249631770106420420800",
                "13329037918321916750635360960560216216",
                "124106548524256397338099972407812438566",
                "135413127732986006087385998628731879304",
                "267118094955375048136593096419386963922",
                "165116054030784881803960344067151421879",
                "167426711835917437686251010290390865419",
                "43663463163716083275745711154369000923",
                "6214313420129133921574649279705809532",
                "120845663189302050089754362357217502321",
                "231406778493313832026102907713773625417",
                "155684616493574774319958969263345876555",
                "183674312749361721104417825406206283907",
                "213073342072681522308586930809976002253",
                "182243189301921101630549684984445045723",
                "124018683960523764461939711953602010273",
                "197312899671925156477198882123432516320"
            ]
        },
        "deprecated": false,
        "signature_version": "v1"
    },
    {
        "id": "CVE-2025-38037-42ca171a",
        "target": {
            "file": "drivers/net/vxlan/vxlan_core.c"
        },
        "signature_type": "Line",
        "source": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git@a6644aeb8ddf196dec5f8e782293c36f065df4d7",
        "digest": {
            "threshold": 0.9,
            "line_hashes": [
                "337227118557939908503084289541483005626",
                "92016851049059881980186999922041173476",
                "256328860237151827172669255398520707780",
                "82902102280656710576502982777210611873",
                "121143068329831555142990563949026035450",
                "1547948656395481214145460225656691709",
                "227053147053905290747070094416838373648",
                "91070087258226488615892952410376555654",
                "271024820205311123893512763499513553202",
                "103868164130355074626911838203044791182",
                "139093221690187512779433414184419208701",
                "119980346355488153096297113723034375897",
                "265979125269309282450839725226671365570",
                "308881916453951564484322922134101095259",
                "209460378706944378698268287315686711329",
                "315289644549991886249631770106420420800",
                "13329037918321916750635360960560216216",
                "124106548524256397338099972407812438566",
                "135413127732986006087385998628731879304",
                "267118094955375048136593096419386963922",
                "165116054030784881803960344067151421879",
                "167426711835917437686251010290390865419",
                "43663463163716083275745711154369000923",
                "6214313420129133921574649279705809532",
                "120845663189302050089754362357217502321",
                "231406778493313832026102907713773625417",
                "155684616493574774319958969263345876555",
                "183674312749361721104417825406206283907",
                "213073342072681522308586930809976002253",
                "182243189301921101630549684984445045723",
                "124018683960523764461939711953602010273",
                "197312899671925156477198882123432516320"
            ]
        },
        "deprecated": false,
        "signature_version": "v1"
    },
    {
        "id": "CVE-2025-38037-507b091f",
        "target": {
            "function": "vxlan_find_mac",
            "file": "drivers/net/vxlan/vxlan_core.c"
        },
        "signature_type": "Function",
        "source": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git@13cba3f837903f7184d6e9b6137d5165ffe82a8f",
        "digest": {
            "function_hash": "250226169771840321549440244986642784856",
            "length": 212.0
        },
        "deprecated": false,
        "signature_version": "v1"
    },
    {
        "id": "CVE-2025-38037-7934a283",
        "target": {
            "function": "vxlan_cleanup",
            "file": "drivers/net/vxlan/vxlan_core.c"
        },
        "signature_type": "Function",
        "source": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git@13cba3f837903f7184d6e9b6137d5165ffe82a8f",
        "digest": {
            "function_hash": "279413821421351217762040784548610524356",
            "length": 940.0
        },
        "deprecated": false,
        "signature_version": "v1"
    },
    {
        "id": "CVE-2025-38037-795e7bdc",
        "target": {
            "function": "vxlan_fdb_update_existing",
            "file": "drivers/net/vxlan/vxlan_core.c"
        },
        "signature_type": "Function",
        "source": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git@a6644aeb8ddf196dec5f8e782293c36f065df4d7",
        "digest": {
            "function_hash": "297090309149676216208908191773244992786",
            "length": 1938.0
        },
        "deprecated": false,
        "signature_version": "v1"
    },
    {
        "id": "CVE-2025-38037-9108ef4b",
        "target": {
            "function": "vxlan_snoop",
            "file": "drivers/net/vxlan/vxlan_core.c"
        },
        "signature_type": "Function",
        "source": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git@13cba3f837903f7184d6e9b6137d5165ffe82a8f",
        "digest": {
            "function_hash": "284902108426095043404729802135770872898",
            "length": 1304.0
        },
        "deprecated": false,
        "signature_version": "v1"
    },
    {
        "id": "CVE-2025-38037-9600d37e",
        "target": {
            "function": "vxlan_fdb_info",
            "file": "drivers/net/vxlan/vxlan_core.c"
        },
        "signature_type": "Function",
        "source": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git@a6644aeb8ddf196dec5f8e782293c36f065df4d7",
        "digest": {
            "function_hash": "118494399801846170342639498204710630025",
            "length": 2554.0
        },
        "deprecated": false,
        "signature_version": "v1"
    },
    {
        "id": "CVE-2025-38037-f04cab35",
        "target": {
            "function": "vxlan_fdb_update_existing",
            "file": "drivers/net/vxlan/vxlan_core.c"
        },
        "signature_type": "Function",
        "source": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git@13cba3f837903f7184d6e9b6137d5165ffe82a8f",
        "digest": {
            "function_hash": "297090309149676216208908191773244992786",
            "length": 1938.0
        },
        "deprecated": false,
        "signature_version": "v1"
    },
    {
        "id": "CVE-2025-38037-f8aece5d",
        "target": {
            "function": "vxlan_fdb_info",
            "file": "drivers/net/vxlan/vxlan_core.c"
        },
        "signature_type": "Function",
        "source": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git@13cba3f837903f7184d6e9b6137d5165ffe82a8f",
        "digest": {
            "function_hash": "118494399801846170342639498204710630025",
            "length": 2554.0
        },
        "deprecated": false,
        "signature_version": "v1"
    },
    {
        "id": "CVE-2025-38037-fb61b5de",
        "target": {
            "function": "vxlan_cleanup",
            "file": "drivers/net/vxlan/vxlan_core.c"
        },
        "signature_type": "Function",
        "source": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git@a6644aeb8ddf196dec5f8e782293c36f065df4d7",
        "digest": {
            "function_hash": "279413821421351217762040784548610524356",
            "length": 940.0
        },
        "deprecated": false,
        "signature_version": "v1"
    },
    {
        "id": "CVE-2025-38037-fc29989f",
        "target": {
            "function": "vxlan_find_mac",
            "file": "drivers/net/vxlan/vxlan_core.c"
        },
        "signature_type": "Function",
        "source": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git@a6644aeb8ddf196dec5f8e782293c36f065df4d7",
        "digest": {
            "function_hash": "250226169771840321549440244986642784856",
            "length": 212.0
        },
        "deprecated": false,
        "signature_version": "v1"
    }
]