CVE-2024-26596

{"id": "CVE-2024-26596", "metrics": {"cvssMetricV31": [{"type": "Primary", "source": "nvd@nist.gov", "cvssData": {"scope": "UNCHANGED", "version": "3.1", "baseScore": 5.5, "attackVector": "LOCAL", "baseSeverity": "MEDIUM", "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H", "integrityImpact": "NONE", "userInteraction": "NONE", "attackComplexity": "LOW", "availabilityImpact": "HIGH", "privilegesRequired": "LOW", "confidentialityImpact": "NONE"}, "impactScore": 3.6, "exploitabilityScore": 1.8}]}, "published": "2024-02-23T15:15:09.500", "references": [{"url": "https://git.kernel.org/stable/c/844f104790bd69c2e4dbb9ee3eba46fde1fcea7b", "tags": ["Patch"], "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"}, {"url": "https://git.kernel.org/stable/c/dbd909c20c11f0d29c0054d41e0d1f668a60e8c8", "tags": ["Patch"], "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"}], "vulnStatus": "Analyzed", "weaknesses": [{"type": "Primary", "source": "nvd@nist.gov", "description": [{"lang": "en", "value": "NVD-CWE-noinfo"}]}], "descriptions": [{"lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nnet: dsa: fix netdev_priv() dereference before check on non-DSA netdevice events\n\nAfter the blamed commit, we started doing this dereference for every\nNETDEV_CHANGEUPPER and NETDEV_PRECHANGEUPPER event in the system.\n\nstatic inline struct dsa_port *dsa_user_to_port(const struct net_device *dev)\n{\n\tstruct dsa_user_priv *p = netdev_priv(dev);\n\n\treturn p->dp;\n}\n\nWhich is obviously bogus, because not all net_devices have a netdev_priv()\nof type struct dsa_user_priv. But struct dsa_user_priv is fairly small,\nand p->dp means dereferencing 8 bytes starting with offset 16. Most\ndrivers allocate that much private memory anyway, making our access not\nfault, and we discard the bogus data quickly afterwards, so this wasn't\ncaught.\n\nBut the dummy interface is somewhat special in that it calls\nalloc_netdev() with a priv size of 0. So every netdev_priv() dereference\nis invalid, and we get this when we emit a NETDEV_PRECHANGEUPPER event\nwith a VLAN as its new upper:\n\n$ ip link add dummy1 type dummy\n$ ip link add link dummy1 name dummy1.100 type vlan id 100\n[ 43.309174] ==================================================================\n[ 43.316456] BUG: KASAN: slab-out-of-bounds in dsa_user_prechangeupper+0x30/0xe8\n[ 43.323835] Read of size 8 at addr ffff3f86481d2990 by task ip/374\n[ 43.330058]\n[ 43.342436] Call trace:\n[ 43.366542] dsa_user_prechangeupper+0x30/0xe8\n[ 43.371024] dsa_user_netdevice_event+0xb38/0xee8\n[ 43.375768] notifier_call_chain+0xa4/0x210\n[ 43.379985] raw_notifier_call_chain+0x24/0x38\n[ 43.384464] __netdev_upper_dev_link+0x3ec/0x5d8\n[ 43.389120] netdev_upper_dev_link+0x70/0xa8\n[ 43.393424] register_vlan_dev+0x1bc/0x310\n[ 43.397554] vlan_newlink+0x210/0x248\n[ 43.401247] rtnl_newlink+0x9fc/0xe30\n[ 43.404942] rtnetlink_rcv_msg+0x378/0x580\n\nAvoid the kernel oops by dereferencing after the type check, as customary."}, {"lang": "es", "value": "En el kernel de Linux, se resolvi\u00f3 la siguiente vulnerabilidad: net: dsa: corrige la desreferencia de netdev_priv() antes de verificar los eventos de dispositivos de red que no son DSA Despu\u00e9s del compromiso culpable, comenzamos a hacer esta desreferencia para cada evento NETDEV_CHANGEUPPER y NETDEV_PRECHANGEUPPER en el sistema. estructura est\u00e1tica en l\u00ednea dsa_port *dsa_user_to_port(const struct net_device *dev) { struct dsa_user_priv *p = netdev_priv(dev); devolver p->dp; } Lo cual es obviamente falso, porque no todos los net_devices tienen un netdev_priv() de tipo struct dsa_user_priv. Pero la estructura dsa_user_priv es bastante peque\u00f1a, y p->dp significa desreferenciar 8 bytes comenzando con el desplazamiento 16. La mayor\u00eda de los controladores asignan esa cantidad de memoria privada de todos modos, lo que hace que nuestro acceso no sea un error, y descartamos los datos falsos r\u00e1pidamente despu\u00e9s, por lo que esto no fue as\u00ed. atrap\u00f3. Pero la interfaz ficticia es algo especial porque llama a alloc_netdev() con un tama\u00f1o privado de 0. Por lo tanto, cada desreferencia de netdev_priv() no es v\u00e1lida, y obtenemos esto cuando emitimos un evento NETDEV_PRECHANGEUPPER con una VLAN como nueva superior: $ ip enlace agregar dummy1 tipo dummy $ ip enlace agregar enlace dummy1 nombre dummy1.100 tipo vlan id 100 [43.309174] ============================= ======================================= [43.316456] ERROR: KASAN: losa fuera de -bounds en dsa_user_prechangeupper+0x30/0xe8 [ 43.323835] Lectura de tama\u00f1o 8 en addr ffff3f86481d2990 por tarea ip/374 [ 43.330058] [ 43.342436] Rastreo de llamadas: [ 43.366542] dsa_user_prechangeupper+0x30/0xe8 [ 43.371024] dsa_user_netdevice_event+0xb38/0xee8 [ 43.375768 ] notifier_call_chain+0xa4/0x210 [ 43.379985] raw_notifier_call_chain+0x24/0x38 [ 43.384464] __netdev_upper_dev_link+0x3ec/0x5d8 [ 43.389120] netdev_upper_dev_link+0x70/0xa8 [ 43.3 93424] registrar_vlan_dev+0x1bc/0x310 [ 43.397554] vlan_newlink+0x210/0x248 [ 43.401247] rtnl_newlink +0x9fc/0xe30 [ 43.404942] rtnetlink_rcv_msg+0x378/0x580 Evite los errores del kernel desreferenciando despu\u00e9s de la verificaci\u00f3n de tipo, como es habitual."}], "lastModified": "2024-04-17T19:54:59.240", "configurations": [{"nodes": [{"negate": false, "cpeMatch": [{"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "vulnerable": true, "matchCriteriaId": "9D0FCB67-1966-41C4-BCD4-66C3CA68D4B5", "versionEndExcluding": "6.7.2", "versionStartIncluding": "6.1.0"}], "operator": "OR"}]}], "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"}