{
   "containers": {
      "cna": {
         "providerMetadata": {
            "orgId": "f4215fc3-5b6b-47ff-a258-f7189bd81038"
         },
         "descriptions": [
            {
               "lang": "en",
               "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nbpf: Fix racing between bpf_timer_cancel_and_free and bpf_timer_cancel\n\nThe following race is possible between bpf_timer_cancel_and_free\nand bpf_timer_cancel. It will lead a UAF on the timer->timer.\n\nbpf_timer_cancel();\n\tspin_lock();\n\tt = timer->time;\n\tspin_unlock();\n\n\t\t\t\t\tbpf_timer_cancel_and_free();\n\t\t\t\t\t\tspin_lock();\n\t\t\t\t\t\tt = timer->timer;\n\t\t\t\t\t\ttimer->timer = NULL;\n\t\t\t\t\t\tspin_unlock();\n\t\t\t\t\t\thrtimer_cancel(&t->timer);\n\t\t\t\t\t\tkfree(t);\n\n\t/* UAF on t */\n\thrtimer_cancel(&t->timer);\n\nIn bpf_timer_cancel_and_free, this patch frees the timer->timer\nafter a rcu grace period. This requires a rcu_head addition\nto the \"struct bpf_hrtimer\". Another kfree(t) happens in bpf_timer_init,\nthis does not need a kfree_rcu because it is still under the\nspin_lock and timer->timer has not been visible by others yet.\n\nIn bpf_timer_cancel, rcu_read_lock() is added because this helper\ncan be used in a non rcu critical section context (e.g. from\na sleepable bpf prog). Other timer->timer usages in helpers.c\nhave been audited, bpf_timer_cancel() is the only place where\ntimer->timer is used outside of the spin_lock.\n\nAnother solution considered is to mark a t->flag in bpf_timer_cancel\nand clear it after hrtimer_cancel() is done.  In bpf_timer_cancel_and_free,\nit busy waits for the flag to be cleared before kfree(t). This patch\ngoes with a straight forward solution and frees timer->timer after\na rcu grace period."
            }
         ],
         "affected": [
            {
               "product": "Linux",
               "vendor": "Linux",
               "defaultStatus": "unaffected",
               "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
               "programFiles": [
                  "kernel/bpf/helpers.c"
               ],
               "versions": [
                  {
                     "version": "b00628b1c7d5",
                     "lessThan": "5268bb02107b",
                     "status": "affected",
                     "versionType": "git"
                  },
                  {
                     "version": "b00628b1c7d5",
                     "lessThan": "addf5e297e6c",
                     "status": "affected",
                     "versionType": "git"
                  },
                  {
                     "version": "b00628b1c7d5",
                     "lessThan": "8327ed12e8eb",
                     "status": "affected",
                     "versionType": "git"
                  },
                  {
                     "version": "b00628b1c7d5",
                     "lessThan": "7d80a9e745fa",
                     "status": "affected",
                     "versionType": "git"
                  },
                  {
                     "version": "b00628b1c7d5",
                     "lessThan": "0281b919e175",
                     "status": "affected",
                     "versionType": "git"
                  }
               ]
            },
            {
               "product": "Linux",
               "vendor": "Linux",
               "defaultStatus": "affected",
               "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
               "programFiles": [
                  "kernel/bpf/helpers.c"
               ],
               "versions": [
                  {
                     "version": "5.15",
                     "status": "affected"
                  },
                  {
                     "version": "0",
                     "lessThan": "5.15",
                     "status": "unaffected",
                     "versionType": "custom"
                  },
                  {
                     "version": "5.15.150",
                     "lessThanOrEqual": "5.15.*",
                     "status": "unaffected",
                     "versionType": "custom"
                  },
                  {
                     "version": "6.1.80",
                     "lessThanOrEqual": "6.1.*",
                     "status": "unaffected",
                     "versionType": "custom"
                  },
                  {
                     "version": "6.6.19",
                     "lessThanOrEqual": "6.6.*",
                     "status": "unaffected",
                     "versionType": "custom"
                  },
                  {
                     "version": "6.7.7",
                     "lessThanOrEqual": "6.7.*",
                     "status": "unaffected",
                     "versionType": "custom"
                  },
                  {
                     "version": "6.8",
                     "lessThanOrEqual": "*",
                     "status": "unaffected",
                     "versionType": "original_commit_for_fix"
                  }
               ]
            }
         ],
         "references": [
            {
               "url": "https://git.kernel.org/stable/c/5268bb02107b9eedfdcd51db75b407d10043368c"
            },
            {
               "url": "https://git.kernel.org/stable/c/addf5e297e6cbf5341f9c07720693ca9ba0057b5"
            },
            {
               "url": "https://git.kernel.org/stable/c/8327ed12e8ebc5436bfaa1786c49988894f9c8a6"
            },
            {
               "url": "https://git.kernel.org/stable/c/7d80a9e745fa5b47da3bca001f186c02485c7c33"
            },
            {
               "url": "https://git.kernel.org/stable/c/0281b919e175bb9c3128bd3872ac2903e9436e3f"
            }
         ],
         "title": "bpf: Fix racing between bpf_timer_cancel_and_free and bpf_timer_cancel",
         "x_generator": {
            "engine": "bippy-a5840b7849dd"
         }
      }
   },
   "cveMetadata": {
      "assignerOrgId": "f4215fc3-5b6b-47ff-a258-f7189bd81038",
      "cveID": "CVE-2024-26737",
      "requesterUserId": "gregkh@kernel.org",
      "serial": "1",
      "state": "PUBLISHED"
   },
   "dataType": "CVE_RECORD",
   "dataVersion": "5.0"
}