CVE-2024-43837

{"id": "CVE-2024-43837", "cveTags": [], "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": "2024-08-17T10:15:09.320", "references": [{"url": "https://git.kernel.org/stable/c/9d40fd516aeae6779e3c84c6b96700ca76285847", "tags": ["Patch"], "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"}, {"url": "https://git.kernel.org/stable/c/b29a880bb145e1f1c1df5ab88ed26b1495ff9f09", "tags": ["Patch"], "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"}, {"url": "https://git.kernel.org/stable/c/f7866c35873377313ff94398f17d425b28b71de1", "tags": ["Patch"], "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"}, {"url": "https://git.kernel.org/stable/c/fcac5feb06f31ee4c88bca9bf98d8bc3ca7d2615", "tags": ["Patch"], "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"}], "vulnStatus": "Analyzed", "weaknesses": [{"type": "Primary", "source": "nvd@nist.gov", "description": [{"lang": "en", "value": "CWE-476"}]}], "descriptions": [{"lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nbpf: Fix null pointer dereference in resolve_prog_type() for BPF_PROG_TYPE_EXT\n\nWhen loading a EXT program without specifying `attr->attach_prog_fd`,\nthe `prog->aux->dst_prog` will be null. At this time, calling\nresolve_prog_type() anywhere will result in a null pointer dereference.\n\nExample stack trace:\n\n[ 8.107863] Unable to handle kernel NULL pointer dereference at virtual address 0000000000000004\n[ 8.108262] Mem abort info:\n[ 8.108384] ESR = 0x0000000096000004\n[ 8.108547] EC = 0x25: DABT (current EL), IL = 32 bits\n[ 8.108722] SET = 0, FnV = 0\n[ 8.108827] EA = 0, S1PTW = 0\n[ 8.108939] FSC = 0x04: level 0 translation fault\n[ 8.109102] Data abort info:\n[ 8.109203] ISV = 0, ISS = 0x00000004, ISS2 = 0x00000000\n[ 8.109399] CM = 0, WnR = 0, TnD = 0, TagAccess = 0\n[ 8.109614] GCS = 0, Overlay = 0, DirtyBit = 0, Xs = 0\n[ 8.109836] user pgtable: 4k pages, 48-bit VAs, pgdp=0000000101354000\n[ 8.110011] [0000000000000004] pgd=0000000000000000, p4d=0000000000000000\n[ 8.112624] Internal error: Oops: 0000000096000004 [#1] PREEMPT SMP\n[ 8.112783] Modules linked in:\n[ 8.113120] CPU: 0 PID: 99 Comm: may_access_dire Not tainted 6.10.0-rc3-next-20240613-dirty #1\n[ 8.113230] Hardware name: linux,dummy-virt (DT)\n[ 8.113390] pstate: 60000005 (nZCv daif -PAN -UAO -TCO -DIT -SSBS BTYPE=--)\n[ 8.113429] pc : may_access_direct_pkt_data+0x24/0xa0\n[ 8.113746] lr : add_subprog_and_kfunc+0x634/0x8e8\n[ 8.113798] sp : ffff80008283b9f0\n[ 8.113813] x29: ffff80008283b9f0 x28: ffff800082795048 x27: 0000000000000001\n[ 8.113881] x26: ffff0000c0bb2600 x25: 0000000000000000 x24: 0000000000000000\n[ 8.113897] x23: ffff0000c1134000 x22: 000000000001864f x21: ffff0000c1138000\n[ 8.113912] x20: 0000000000000001 x19: ffff0000c12b8000 x18: ffffffffffffffff\n[ 8.113929] x17: 0000000000000000 x16: 0000000000000000 x15: 0720072007200720\n[ 8.113944] x14: 0720072007200720 x13: 0720072007200720 x12: 0720072007200720\n[ 8.113958] x11: 0720072007200720 x10: 0000000000f9fca4 x9 : ffff80008021f4e4\n[ 8.113991] x8 : 0101010101010101 x7 : 746f72705f6d656d x6 : 000000001e0e0f5f\n[ 8.114006] x5 : 000000000001864f x4 : ffff0000c12b8000 x3 : 000000000000001c\n[ 8.114020] x2 : 0000000000000002 x1 : 0000000000000000 x0 : 0000000000000000\n[ 8.114126] Call trace:\n[ 8.114159] may_access_direct_pkt_data+0x24/0xa0\n[ 8.114202] bpf_check+0x3bc/0x28c0\n[ 8.114214] bpf_prog_load+0x658/0xa58\n[ 8.114227] __sys_bpf+0xc50/0x2250\n[ 8.114240] __arm64_sys_bpf+0x28/0x40\n[ 8.114254] invoke_syscall.constprop.0+0x54/0xf0\n[ 8.114273] do_el0_svc+0x4c/0xd8\n[ 8.114289] el0_svc+0x3c/0x140\n[ 8.114305] el0t_64_sync_handler+0x134/0x150\n[ 8.114331] el0t_64_sync+0x168/0x170\n[ 8.114477] Code: 7100707f 54000081 f9401c00 f9403800 (b9400403)\n[ 8.118672] ---[ end trace 0000000000000000 ]---\n\nOne way to fix it is by forcing `attach_prog_fd` non-empty when\nbpf_prog_load(). But this will lead to `libbpf_probe_bpf_prog_type`\nAPI broken which use verifier log to probe prog type and will log\nnothing if we reject invalid EXT prog before bpf_check().\n\nAnother way is by adding null check in resolve_prog_type().\n\nThe issue was introduced by commit 4a9c7bbe2ed4 (\"bpf: Resolve to\nprog->aux->dst_prog->type only for BPF_PROG_TYPE_EXT\") which wanted\nto correct type resolution for BPF_PROG_TYPE_TRACING programs. Before\nthat, the type resolution of BPF_PROG_TYPE_EXT prog actually follows\nthe logic below:\n\n prog->aux->dst_prog ? prog->aux->dst_prog->type : prog->type;\n\nIt implies that when EXT program is not yet attached to `dst_prog`,\nthe prog type should be EXT itself. This code worked fine in the past.\nSo just keep using it.\n\nFix this by returning `prog->type` for BPF_PROG_TYPE_EXT if `dst_prog`\nis not present in resolve_prog_type()."}, {"lang": "es", "value": "En el kernel de Linux, se ha resuelto la siguiente vulnerabilidad: bpf: Se corrigi\u00f3 la desreferencia del puntero nulo en resolve_prog_type() para BPF_PROG_TYPE_EXT Al cargar un programa EXT sin especificar `attr->attach_prog_fd`, el `prog->aux->dst_prog` ser\u00e1 nulo. En este momento, llamar a resolve_prog_type() en cualquier lugar dar\u00e1 como resultado una desreferencia del puntero nulo. Ejemplo de seguimiento de pila: [8.107863] No se puede manejar la desreferencia del puntero NULL del kernel en la direcci\u00f3n virtual 0000000000000004 [8.108262] Informaci\u00f3n de cancelaci\u00f3n de memoria: [8.108384] ESR = 0x0000000096000004 [8.108547] EC = 0x25: DABT (EL actual), IL = 32 bits [8.108722 ] SET = 0, FnV = 0 [8.108827] EA = 0, S1PTW = 0 [8.108939] FSC = 0x04: error de traducci\u00f3n de nivel 0 [8.109102] Informaci\u00f3n de cancelaci\u00f3n de datos: [8.109203] ISV = 0, ISS = 0x00000004, ISS2 = 00 [ 8.109399] CM = 0, WnR = 0, TnD = 0, TagAccess = 0 [ 8.109614] GCS = 0, Overlay = 0, DirtyBit = 0, Xs = 0 [ 8.109836] tabla de p\u00e1ginas de usuario: p\u00e1ginas de 4k, VA de 48 bits, pgdp=0000000101354000 [8.110011] [00000000000000004] pgd=0000000000000000, p4d=0000000000000000 [8.112624] Error interno: Vaya: 0000000096000 004 [#1] PREEMPT SMP [8.112783] M\u00f3dulos vinculados en: [8.113120] CPU: 0 PID: 99 Comm: may_access_dire No contaminado 6.10.0-rc3-next-20240613-dirty #1 [8.113230] Nombre de hardware: linux,dummy-virt (DT) [8.113390] pstate: 60000005 (nZCv daif -PAN -UAO -TCO -DIT -SSBS BTYPE= --) [8.113429] pc: may_access_direct_pkt_data+0x24/0xa0 [8.113746] lr: add_subprog_and_kfunc+0x634/0x8e8 [8.113798] sp: ffff80008283b9f0 [8.113813] x29: 83b9f0 x28: ffff800082795048 x27: 00000000000000001 [ 8.113881] x26: ffff0000c0bb2600 x25: 0000000000000000 x24: 0000000000000000 [8.113897] x23: ffff0000c1134000 x22: 000000000001864f x21: ffff0000c1138000 [8.113912] x20: 0000000000000001 x19: ffff0000c12b8000 x18: ffffffffffffffff [ 8.113929] x17: 0000000000000000 x16: 00000000000000000 x15: 0720072007200720 [ 8.113944] x14: 20072007200720 x13: 0720072007200720 x12: 0720072007200720 [8.113958] x11: 0720072007200720 x10: 0000000000f9fca4 x9: ffff80008021f4e4 [8.113991] x8: 0101010101010101 x7: 46f72705f6d656d x6: 000000001e0e0f5f [8.114006] x5: 000000000001864f x4: ffff0000c12b8000 x3: 000000000000001c [8.114020] x2: 00000000002 x1: 0000000000000000 x0: 0000000000000000 [ 8.114126] Seguimiento de llamadas: [8.114159] may_access_direct_pkt_data+0x24/0xa0 [8.114202] bpf_check+0x3bc/0x28c0 [8.114214] bpf_prog_load+0x658/0xa58 [8.114227] xc50/0x2250 [8.114240] __arm64_sys_bpf+0x28/0x40 [8.114254] invoke_syscall. constprop.0+0x54/0xf0 [8.114273] do_el0_svc+0x4c/0xd8 [8.114289] el0_svc+0x3c/0x140 [8.114305] el0t_64_sync_handler+0x134/0x150 [8.114331] _sync+0x168/0x170 [8.114477] C\u00f3digo: 7100707f 54000081 f9401c00 f9403800 (b9400403 ) [8.118672] ---[ end trace 0000000000000000 ]--- Una forma de solucionarlo es forzando que `attach_prog_fd` no est\u00e9 vac\u00edo cuando bpf_prog_load(). Pero esto provocar\u00e1 que se rompa la API `libbpf_probe_bpf_prog_type`, que utiliza el registro del verificador para sondear el tipo de programa y no registrar\u00e1 nada si rechazamos el programa EXT no v\u00e1lido antes de bpf_check(). Otra forma es agregando una verificaci\u00f3n nula en resolve_prog_type(). El problema fue introducido por el commit 4a9c7bbe2ed4 (\"bpf: Resolve to prog->aux->dst_prog->type only for BPF_PROG_TYPE_EXT\") que quer\u00eda corregir la resoluci\u00f3n de tipos para los programas BPF_PROG_TYPE_TRACING. Antes de eso, la resoluci\u00f3n de tipo del programa BPF_PROG_TYPE_EXT en realidad sigue la siguiente l\u00f3gica: prog->aux->dst_prog ? prog->aux->dst_prog->tipo : prog->tipo; Implica que cuando el programa EXT a\u00fan no est\u00e1 adjunto a `dst_prog`, el tipo de programa debe ser EXT. Este c\u00f3digo funcion\u00f3 bien en el pasado. As\u00ed que sigue us\u00e1ndolo. Solucione este problema devolviendo `prog->type` para BPF_PROG_TYPE_EXT si `dst_prog` no est\u00e1 presente en resolve_prog_type()."}], "lastModified": "2024-08-22T15:44:03.417", "configurations": [{"nodes": [{"negate": false, "cpeMatch": [{"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "vulnerable": true, "matchCriteriaId": "ADED9C16-75E2-47CC-A756-30929EBBF848", "versionEndExcluding": "6.1.103", "versionStartIncluding": "5.18"}, {"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "vulnerable": true, "matchCriteriaId": "CC912330-6B41-4C6B-99AF-F3857FBACB6A", "versionEndExcluding": "6.6.44", "versionStartIncluding": "6.2"}, {"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "vulnerable": true, "matchCriteriaId": "92D388F2-1EAF-4CFA-AC06-5B26D762EA7D", "versionEndExcluding": "6.10.3", "versionStartIncluding": "6.7"}], "operator": "OR"}]}], "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"}