gsd-2022-48644
Vulnerability from gsd
Modified
2024-02-26 06:00
Details
In the Linux kernel, the following vulnerability has been resolved: net/sched: taprio: avoid disabling offload when it was never enabled In an incredibly strange API design decision, qdisc->destroy() gets called even if qdisc->init() never succeeded, not exclusively since commit 87b60cfacf9f ("net_sched: fix error recovery at qdisc creation"), but apparently also earlier (in the case of qdisc_create_dflt()). The taprio qdisc does not fully acknowledge this when it attempts full offload, because it starts off with q->flags = TAPRIO_FLAGS_INVALID in taprio_init(), then it replaces q->flags with TCA_TAPRIO_ATTR_FLAGS parsed from netlink (in taprio_change(), tail called from taprio_init()). But in taprio_destroy(), we call taprio_disable_offload(), and this determines what to do based on FULL_OFFLOAD_IS_ENABLED(q->flags). But looking at the implementation of FULL_OFFLOAD_IS_ENABLED() (a bitwise check of bit 1 in q->flags), it is invalid to call this macro on q->flags when it contains TAPRIO_FLAGS_INVALID, because that is set to U32_MAX, and therefore FULL_OFFLOAD_IS_ENABLED() will return true on an invalid set of flags. As a result, it is possible to crash the kernel if user space forces an error between setting q->flags = TAPRIO_FLAGS_INVALID, and the calling of taprio_enable_offload(). This is because drivers do not expect the offload to be disabled when it was never enabled. The error that we force here is to attach taprio as a non-root qdisc, but instead as child of an mqprio root qdisc: $ tc qdisc add dev swp0 root handle 1: \ mqprio num_tc 8 map 0 1 2 3 4 5 6 7 \ queues 1@0 1@1 1@2 1@3 1@4 1@5 1@6 1@7 hw 0 $ tc qdisc replace dev swp0 parent 1:1 \ taprio num_tc 8 map 0 1 2 3 4 5 6 7 \ queues 1@0 1@1 1@2 1@3 1@4 1@5 1@6 1@7 base-time 0 \ sched-entry S 0x7f 990000 sched-entry S 0x80 100000 \ flags 0x0 clockid CLOCK_TAI Unable to handle kernel paging request at virtual address fffffffffffffff8 [fffffffffffffff8] pgd=0000000000000000, p4d=0000000000000000 Internal error: Oops: 96000004 [#1] PREEMPT SMP Call trace: taprio_dump+0x27c/0x310 vsc9959_port_setup_tc+0x1f4/0x460 felix_port_setup_tc+0x24/0x3c dsa_slave_setup_tc+0x54/0x27c taprio_disable_offload.isra.0+0x58/0xe0 taprio_destroy+0x80/0x104 qdisc_create+0x240/0x470 tc_modify_qdisc+0x1fc/0x6b0 rtnetlink_rcv_msg+0x12c/0x390 netlink_rcv_skb+0x5c/0x130 rtnetlink_rcv+0x1c/0x2c Fix this by keeping track of the operations we made, and undo the offload only if we actually did it. I've added "bool offloaded" inside a 4 byte hole between "int clockid" and "atomic64_t picos_per_byte". Now the first cache line looks like below: $ pahole -C taprio_sched net/sched/sch_taprio.o struct taprio_sched { struct Qdisc * * qdiscs; /* 0 8 */ struct Qdisc * root; /* 8 8 */ u32 flags; /* 16 4 */ enum tk_offsets tk_offset; /* 20 4 */ int clockid; /* 24 4 */ bool offloaded; /* 28 1 */ /* XXX 3 bytes hole, try to pack */ atomic64_t picos_per_byte; /* 32 0 */ /* XXX 8 bytes hole, try to pack */ spinlock_t current_entry_lock; /* 40 0 */ /* XXX 8 bytes hole, try to pack */ struct sched_entry * current_entry; /* 48 8 */ struct sched_gate_list * oper_sched; /* 56 8 */ /* --- cacheline 1 boundary (64 bytes) --- */
Aliases



{
  "gsd": {
    "metadata": {
      "exploitCode": "unknown",
      "remediation": "unknown",
      "reportConfidence": "confirmed",
      "type": "vulnerability"
    },
    "osvSchema": {
      "aliases": [
        "CVE-2022-48644"
      ],
      "details": "In the Linux kernel, the following vulnerability has been resolved:\n\nnet/sched: taprio: avoid disabling offload when it was never enabled\n\nIn an incredibly strange API design decision, qdisc-\u003edestroy() gets\ncalled even if qdisc-\u003einit() never succeeded, not exclusively since\ncommit 87b60cfacf9f (\"net_sched: fix error recovery at qdisc creation\"),\nbut apparently also earlier (in the case of qdisc_create_dflt()).\n\nThe taprio qdisc does not fully acknowledge this when it attempts full\noffload, because it starts off with q-\u003eflags = TAPRIO_FLAGS_INVALID in\ntaprio_init(), then it replaces q-\u003eflags with TCA_TAPRIO_ATTR_FLAGS\nparsed from netlink (in taprio_change(), tail called from taprio_init()).\n\nBut in taprio_destroy(), we call taprio_disable_offload(), and this\ndetermines what to do based on FULL_OFFLOAD_IS_ENABLED(q-\u003eflags).\n\nBut looking at the implementation of FULL_OFFLOAD_IS_ENABLED()\n(a bitwise check of bit 1 in q-\u003eflags), it is invalid to call this macro\non q-\u003eflags when it contains TAPRIO_FLAGS_INVALID, because that is set\nto U32_MAX, and therefore FULL_OFFLOAD_IS_ENABLED() will return true on\nan invalid set of flags.\n\nAs a result, it is possible to crash the kernel if user space forces an\nerror between setting q-\u003eflags = TAPRIO_FLAGS_INVALID, and the calling\nof taprio_enable_offload(). This is because drivers do not expect the\noffload to be disabled when it was never enabled.\n\nThe error that we force here is to attach taprio as a non-root qdisc,\nbut instead as child of an mqprio root qdisc:\n\n$ tc qdisc add dev swp0 root handle 1: \\\n\tmqprio num_tc 8 map 0 1 2 3 4 5 6 7 \\\n\tqueues 1@0 1@1 1@2 1@3 1@4 1@5 1@6 1@7 hw 0\n$ tc qdisc replace dev swp0 parent 1:1 \\\n\ttaprio num_tc 8 map 0 1 2 3 4 5 6 7 \\\n\tqueues 1@0 1@1 1@2 1@3 1@4 1@5 1@6 1@7 base-time 0 \\\n\tsched-entry S 0x7f 990000 sched-entry S 0x80 100000 \\\n\tflags 0x0 clockid CLOCK_TAI\nUnable to handle kernel paging request at virtual address fffffffffffffff8\n[fffffffffffffff8] pgd=0000000000000000, p4d=0000000000000000\nInternal error: Oops: 96000004 [#1] PREEMPT SMP\nCall trace:\n taprio_dump+0x27c/0x310\n vsc9959_port_setup_tc+0x1f4/0x460\n felix_port_setup_tc+0x24/0x3c\n dsa_slave_setup_tc+0x54/0x27c\n taprio_disable_offload.isra.0+0x58/0xe0\n taprio_destroy+0x80/0x104\n qdisc_create+0x240/0x470\n tc_modify_qdisc+0x1fc/0x6b0\n rtnetlink_rcv_msg+0x12c/0x390\n netlink_rcv_skb+0x5c/0x130\n rtnetlink_rcv+0x1c/0x2c\n\nFix this by keeping track of the operations we made, and undo the\noffload only if we actually did it.\n\nI\u0027ve added \"bool offloaded\" inside a 4 byte hole between \"int clockid\"\nand \"atomic64_t picos_per_byte\". Now the first cache line looks like\nbelow:\n\n$ pahole -C taprio_sched net/sched/sch_taprio.o\nstruct taprio_sched {\n        struct Qdisc * *           qdiscs;               /*     0     8 */\n        struct Qdisc *             root;                 /*     8     8 */\n        u32                        flags;                /*    16     4 */\n        enum tk_offsets            tk_offset;            /*    20     4 */\n        int                        clockid;              /*    24     4 */\n        bool                       offloaded;            /*    28     1 */\n\n        /* XXX 3 bytes hole, try to pack */\n\n        atomic64_t                 picos_per_byte;       /*    32     0 */\n\n        /* XXX 8 bytes hole, try to pack */\n\n        spinlock_t                 current_entry_lock;   /*    40     0 */\n\n        /* XXX 8 bytes hole, try to pack */\n\n        struct sched_entry *       current_entry;        /*    48     8 */\n        struct sched_gate_list *   oper_sched;           /*    56     8 */\n        /* --- cacheline 1 boundary (64 bytes) --- */",
      "id": "GSD-2022-48644",
      "modified": "2024-02-26T06:00:31.264442Z",
      "schema_version": "1.4.0"
    }
  },
  "namespaces": {
    "cve.org": {
      "CVE_data_meta": {
        "ASSIGNER": "cve@kernel.org",
        "ID": "CVE-2022-48644",
        "STATE": "PUBLIC"
      },
      "affects": {
        "vendor": {
          "vendor_data": [
            {
              "product": {
                "product_data": [
                  {
                    "product_name": "Linux",
                    "version": {
                      "version_data": [
                        {
                          "version_affected": "\u003c",
                          "version_name": "9c66d1564676",
                          "version_value": "d12a1eb07003"
                        },
                        {
                          "version_value": "not down converted",
                          "x_cve_json_5_version_data": {
                            "defaultStatus": "affected",
                            "versions": [
                              {
                                "status": "affected",
                                "version": "5.4"
                              },
                              {
                                "lessThan": "5.4",
                                "status": "unaffected",
                                "version": "0",
                                "versionType": "custom"
                              },
                              {
                                "lessThanOrEqual": "5.4.*",
                                "status": "unaffected",
                                "version": "5.4.215",
                                "versionType": "custom"
                              },
                              {
                                "lessThanOrEqual": "5.10.*",
                                "status": "unaffected",
                                "version": "5.10.146",
                                "versionType": "custom"
                              },
                              {
                                "lessThanOrEqual": "5.15.*",
                                "status": "unaffected",
                                "version": "5.15.71",
                                "versionType": "custom"
                              },
                              {
                                "lessThanOrEqual": "5.19.*",
                                "status": "unaffected",
                                "version": "5.19.12",
                                "versionType": "custom"
                              },
                              {
                                "lessThanOrEqual": "*",
                                "status": "unaffected",
                                "version": "6.0",
                                "versionType": "original_commit_for_fix"
                              }
                            ]
                          }
                        }
                      ]
                    }
                  }
                ]
              },
              "vendor_name": "Linux"
            }
          ]
        }
      },
      "data_format": "MITRE",
      "data_type": "CVE",
      "data_version": "4.0",
      "description": {
        "description_data": [
          {
            "lang": "eng",
            "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nnet/sched: taprio: avoid disabling offload when it was never enabled\n\nIn an incredibly strange API design decision, qdisc-\u003edestroy() gets\ncalled even if qdisc-\u003einit() never succeeded, not exclusively since\ncommit 87b60cfacf9f (\"net_sched: fix error recovery at qdisc creation\"),\nbut apparently also earlier (in the case of qdisc_create_dflt()).\n\nThe taprio qdisc does not fully acknowledge this when it attempts full\noffload, because it starts off with q-\u003eflags = TAPRIO_FLAGS_INVALID in\ntaprio_init(), then it replaces q-\u003eflags with TCA_TAPRIO_ATTR_FLAGS\nparsed from netlink (in taprio_change(), tail called from taprio_init()).\n\nBut in taprio_destroy(), we call taprio_disable_offload(), and this\ndetermines what to do based on FULL_OFFLOAD_IS_ENABLED(q-\u003eflags).\n\nBut looking at the implementation of FULL_OFFLOAD_IS_ENABLED()\n(a bitwise check of bit 1 in q-\u003eflags), it is invalid to call this macro\non q-\u003eflags when it contains TAPRIO_FLAGS_INVALID, because that is set\nto U32_MAX, and therefore FULL_OFFLOAD_IS_ENABLED() will return true on\nan invalid set of flags.\n\nAs a result, it is possible to crash the kernel if user space forces an\nerror between setting q-\u003eflags = TAPRIO_FLAGS_INVALID, and the calling\nof taprio_enable_offload(). This is because drivers do not expect the\noffload to be disabled when it was never enabled.\n\nThe error that we force here is to attach taprio as a non-root qdisc,\nbut instead as child of an mqprio root qdisc:\n\n$ tc qdisc add dev swp0 root handle 1: \\\n\tmqprio num_tc 8 map 0 1 2 3 4 5 6 7 \\\n\tqueues 1@0 1@1 1@2 1@3 1@4 1@5 1@6 1@7 hw 0\n$ tc qdisc replace dev swp0 parent 1:1 \\\n\ttaprio num_tc 8 map 0 1 2 3 4 5 6 7 \\\n\tqueues 1@0 1@1 1@2 1@3 1@4 1@5 1@6 1@7 base-time 0 \\\n\tsched-entry S 0x7f 990000 sched-entry S 0x80 100000 \\\n\tflags 0x0 clockid CLOCK_TAI\nUnable to handle kernel paging request at virtual address fffffffffffffff8\n[fffffffffffffff8] pgd=0000000000000000, p4d=0000000000000000\nInternal error: Oops: 96000004 [#1] PREEMPT SMP\nCall trace:\n taprio_dump+0x27c/0x310\n vsc9959_port_setup_tc+0x1f4/0x460\n felix_port_setup_tc+0x24/0x3c\n dsa_slave_setup_tc+0x54/0x27c\n taprio_disable_offload.isra.0+0x58/0xe0\n taprio_destroy+0x80/0x104\n qdisc_create+0x240/0x470\n tc_modify_qdisc+0x1fc/0x6b0\n rtnetlink_rcv_msg+0x12c/0x390\n netlink_rcv_skb+0x5c/0x130\n rtnetlink_rcv+0x1c/0x2c\n\nFix this by keeping track of the operations we made, and undo the\noffload only if we actually did it.\n\nI\u0027ve added \"bool offloaded\" inside a 4 byte hole between \"int clockid\"\nand \"atomic64_t picos_per_byte\". Now the first cache line looks like\nbelow:\n\n$ pahole -C taprio_sched net/sched/sch_taprio.o\nstruct taprio_sched {\n        struct Qdisc * *           qdiscs;               /*     0     8 */\n        struct Qdisc *             root;                 /*     8     8 */\n        u32                        flags;                /*    16     4 */\n        enum tk_offsets            tk_offset;            /*    20     4 */\n        int                        clockid;              /*    24     4 */\n        bool                       offloaded;            /*    28     1 */\n\n        /* XXX 3 bytes hole, try to pack */\n\n        atomic64_t                 picos_per_byte;       /*    32     0 */\n\n        /* XXX 8 bytes hole, try to pack */\n\n        spinlock_t                 current_entry_lock;   /*    40     0 */\n\n        /* XXX 8 bytes hole, try to pack */\n\n        struct sched_entry *       current_entry;        /*    48     8 */\n        struct sched_gate_list *   oper_sched;           /*    56     8 */\n        /* --- cacheline 1 boundary (64 bytes) --- */"
          }
        ]
      },
      "generator": {
        "engine": "bippy-d175d3acf727"
      },
      "problemtype": {
        "problemtype_data": [
          {
            "description": [
              {
                "lang": "eng",
                "value": "n/a"
              }
            ]
          }
        ]
      },
      "references": {
        "reference_data": [
          {
            "name": "https://git.kernel.org/stable/c/d12a1eb07003e597077329767c6aa86a7e972c76",
            "refsource": "MISC",
            "url": "https://git.kernel.org/stable/c/d12a1eb07003e597077329767c6aa86a7e972c76"
          },
          {
            "name": "https://git.kernel.org/stable/c/586def6ebed195f3594a4884f7c5334d0e1ad1bb",
            "refsource": "MISC",
            "url": "https://git.kernel.org/stable/c/586def6ebed195f3594a4884f7c5334d0e1ad1bb"
          },
          {
            "name": "https://git.kernel.org/stable/c/f58e43184226e5e9662088ccf1389e424a3a4cbd",
            "refsource": "MISC",
            "url": "https://git.kernel.org/stable/c/f58e43184226e5e9662088ccf1389e424a3a4cbd"
          },
          {
            "name": "https://git.kernel.org/stable/c/c7c9c7eb305ab8b4e93e4e4e1b78d8cfcbc26323",
            "refsource": "MISC",
            "url": "https://git.kernel.org/stable/c/c7c9c7eb305ab8b4e93e4e4e1b78d8cfcbc26323"
          },
          {
            "name": "https://git.kernel.org/stable/c/db46e3a88a09c5cf7e505664d01da7238cd56c92",
            "refsource": "MISC",
            "url": "https://git.kernel.org/stable/c/db46e3a88a09c5cf7e505664d01da7238cd56c92"
          }
        ]
      }
    },
    "nvd.nist.gov": {
      "cve": {
        "descriptions": [
          {
            "lang": "en",
            "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nnet/sched: taprio: avoid disabling offload when it was never enabled\n\nIn an incredibly strange API design decision, qdisc-\u003edestroy() gets\ncalled even if qdisc-\u003einit() never succeeded, not exclusively since\ncommit 87b60cfacf9f (\"net_sched: fix error recovery at qdisc creation\"),\nbut apparently also earlier (in the case of qdisc_create_dflt()).\n\nThe taprio qdisc does not fully acknowledge this when it attempts full\noffload, because it starts off with q-\u003eflags = TAPRIO_FLAGS_INVALID in\ntaprio_init(), then it replaces q-\u003eflags with TCA_TAPRIO_ATTR_FLAGS\nparsed from netlink (in taprio_change(), tail called from taprio_init()).\n\nBut in taprio_destroy(), we call taprio_disable_offload(), and this\ndetermines what to do based on FULL_OFFLOAD_IS_ENABLED(q-\u003eflags).\n\nBut looking at the implementation of FULL_OFFLOAD_IS_ENABLED()\n(a bitwise check of bit 1 in q-\u003eflags), it is invalid to call this macro\non q-\u003eflags when it contains TAPRIO_FLAGS_INVALID, because that is set\nto U32_MAX, and therefore FULL_OFFLOAD_IS_ENABLED() will return true on\nan invalid set of flags.\n\nAs a result, it is possible to crash the kernel if user space forces an\nerror between setting q-\u003eflags = TAPRIO_FLAGS_INVALID, and the calling\nof taprio_enable_offload(). This is because drivers do not expect the\noffload to be disabled when it was never enabled.\n\nThe error that we force here is to attach taprio as a non-root qdisc,\nbut instead as child of an mqprio root qdisc:\n\n$ tc qdisc add dev swp0 root handle 1: \\\n\tmqprio num_tc 8 map 0 1 2 3 4 5 6 7 \\\n\tqueues 1@0 1@1 1@2 1@3 1@4 1@5 1@6 1@7 hw 0\n$ tc qdisc replace dev swp0 parent 1:1 \\\n\ttaprio num_tc 8 map 0 1 2 3 4 5 6 7 \\\n\tqueues 1@0 1@1 1@2 1@3 1@4 1@5 1@6 1@7 base-time 0 \\\n\tsched-entry S 0x7f 990000 sched-entry S 0x80 100000 \\\n\tflags 0x0 clockid CLOCK_TAI\nUnable to handle kernel paging request at virtual address fffffffffffffff8\n[fffffffffffffff8] pgd=0000000000000000, p4d=0000000000000000\nInternal error: Oops: 96000004 [#1] PREEMPT SMP\nCall trace:\n taprio_dump+0x27c/0x310\n vsc9959_port_setup_tc+0x1f4/0x460\n felix_port_setup_tc+0x24/0x3c\n dsa_slave_setup_tc+0x54/0x27c\n taprio_disable_offload.isra.0+0x58/0xe0\n taprio_destroy+0x80/0x104\n qdisc_create+0x240/0x470\n tc_modify_qdisc+0x1fc/0x6b0\n rtnetlink_rcv_msg+0x12c/0x390\n netlink_rcv_skb+0x5c/0x130\n rtnetlink_rcv+0x1c/0x2c\n\nFix this by keeping track of the operations we made, and undo the\noffload only if we actually did it.\n\nI\u0027ve added \"bool offloaded\" inside a 4 byte hole between \"int clockid\"\nand \"atomic64_t picos_per_byte\". Now the first cache line looks like\nbelow:\n\n$ pahole -C taprio_sched net/sched/sch_taprio.o\nstruct taprio_sched {\n        struct Qdisc * *           qdiscs;               /*     0     8 */\n        struct Qdisc *             root;                 /*     8     8 */\n        u32                        flags;                /*    16     4 */\n        enum tk_offsets            tk_offset;            /*    20     4 */\n        int                        clockid;              /*    24     4 */\n        bool                       offloaded;            /*    28     1 */\n\n        /* XXX 3 bytes hole, try to pack */\n\n        atomic64_t                 picos_per_byte;       /*    32     0 */\n\n        /* XXX 8 bytes hole, try to pack */\n\n        spinlock_t                 current_entry_lock;   /*    40     0 */\n\n        /* XXX 8 bytes hole, try to pack */\n\n        struct sched_entry *       current_entry;        /*    48     8 */\n        struct sched_gate_list *   oper_sched;           /*    56     8 */\n        /* --- cacheline 1 boundary (64 bytes) --- */"
          }
        ],
        "id": "CVE-2022-48644",
        "lastModified": "2024-04-28T13:15:07.087",
        "metrics": {},
        "published": "2024-04-28T13:15:07.087",
        "references": [
          {
            "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
            "url": "https://git.kernel.org/stable/c/586def6ebed195f3594a4884f7c5334d0e1ad1bb"
          },
          {
            "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
            "url": "https://git.kernel.org/stable/c/c7c9c7eb305ab8b4e93e4e4e1b78d8cfcbc26323"
          },
          {
            "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
            "url": "https://git.kernel.org/stable/c/d12a1eb07003e597077329767c6aa86a7e972c76"
          },
          {
            "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
            "url": "https://git.kernel.org/stable/c/db46e3a88a09c5cf7e505664d01da7238cd56c92"
          },
          {
            "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
            "url": "https://git.kernel.org/stable/c/f58e43184226e5e9662088ccf1389e424a3a4cbd"
          }
        ],
        "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "vulnStatus": "Received"
      }
    }
  }
}


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