{"id":"CVE-2026-90269","state":"PUBLISHED","title":"bpf: Reject load-acquire from pointers requiring fault protection","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nbpf: Reject load-acquire from pointers requiring fault protection\n\nA BPF_LOAD_ACQ is not rewritten to a BPF_PROBE_MEM load by the verifier,\nunlike a regular BPF_LDX, so the JIT emits a plain load with no exception\ntable entry and a fault panics the kernel instead of being handled.\n\nReject the source pointer types that a BPF_LDX would have had that fault\nprotection applied to, i.e. the ones bpf_convert_ctx_accesses() turns\ninto BPF_PROBE_MEM: a bare PTR_TO_BTF_ID, PTR_TO_BTF_ID | PTR_UNTRUSTED,\nPTR_TO_BTF_ID | MEM_ALLOC | PTR_UNTRUSTED and PTR_TO_MEM | MEM_RDONLY |\nPTR_UNTRUSTED.\n\nThis is reachable e.g. by loading ->mm out of a trusted task_struct\nyields an untrusted pointer to mm_struct, and it is NULL for a kernel\nthread:\n\n  [...]\n  SEC(\"tp_btf/sched_switch\")\n  int BPF_PROG(demo, bool preempt, struct task_struct *prev,\n               struct task_struct *next)\n  {\n      struct mm_struct *mm = next->mm;  /* untrusted */\n\n      out_ldx = (__u64)mm->pgd;         /* BPF_LDX      */\n      out_acq = load_acquire(&mm->pgd); /* BPF_LOAD_ACQ */\n      return 0;\n  }\n  [...]\n\nBoth dereference the same pointer, but only the BPF_LDX is protected\n(x86-64 JIT, jump targets shown prog-relative):\n\n  [...]\n  ; out_ldx = (__u64)mm->pgd;\n  17:   movq    $-10485760, %r10\n  1e:   movq    %rsi, %r11\n  21:   addq    $184, %r11\n  28:   subq    %r10, %r11\n  2b:   movabsq $140737498841088, %r10\n  35:   cmpq    %r10, %r11\n  38:   ja      0x3e                 <-- kernel addr?\n  3a:   xorl    %edi, %edi           <-- no: dst = 0, skip the load\n  3c:   jmp     0x45\n  3e:   movq    184(%rsi), %rdi      <-- yes: load + extable entry\n  [...]\n  ; load_acquire(&mm->pgd)\n  53:\tmovq    %rsi, %rdi\n  56:\tmovq    184(%rdi), %rax       <-- no check, no extable entry\n  [...]\n\nNote that BPF_PROBE_MEM is not visible in a bpftool xlated dump, as\nbpf_insn_prepare_dump() rewrites it back to BPF_MEM.\n\nA PTR_TRUSTED pointer is deliberately not on the list. Such a load is\nnot converted either, but it does not need to be, since the pointer is\nguaranteed live, so load-acquire from it stays allowed.\n\nThe check is gated on BPF_LOAD_ACQ so that atomic RMW and store-release\nerror messages are unchanged; writes (RMW / store-release) to such\npointers are already rejected elsewhere, so only load-acquire needs this.","publishedAt":"2026-09-17T16:08:03.996Z","updatedAt":"2026-10-19T09:00:46.990Z","severity":null,"assigner":"Linux","products":["Linux Linux"],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"880442305a3908589bf4d6fc1d79edb577ee497c","status":"affected","lessThan":"c4c8de3bf48d3756ab0f910fe5cc4937d70efdcd","versionType":"git"},{"version":"880442305a3908589bf4d6fc1d79edb577ee497c","status":"affected","lessThan":"5f8ade6e9b7931fc9697394f1b2c4ae833f5ac18","versionType":"git"},{"version":"880442305a3908589bf4d6fc1d79edb577ee497c","status":"affected","lessThan":"7db0a00445f1a40bacfe9b747405c11cb5f10fc9","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["kernel/bpf/verifier.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"6.15","status":"affected"},{"version":"0","status":"unaffected","lessThan":"6.15","versionType":"semver"},{"version":"6.18.52","status":"unaffected","lessThanOrEqual":"6.18.*","versionType":"semver"},{"version":"7.2.6","status":"unaffected","lessThanOrEqual":"7.2.*","versionType":"semver"},{"version":"7.3","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["kernel/bpf/verifier.c"]}],"references":["https://git.kernel.org/stable/c/c4c8de3bf48d3756ab0f910fe5cc4937d70efdcd","https://git.kernel.org/stable/c/5f8ade6e9b7931fc9697394f1b2c4ae833f5ac18","https://git.kernel.org/stable/c/7db0a00445f1a40bacfe9b747405c11cb5f10fc9"],"weaknesses":[],"ingestedAt":"2026-10-29T20:13:34.582Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/90xxx/CVE-2026-90269.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-90269","state":"PUBLISHED","datePublished":"2026-09-17T16:08:03.996Z","dateUpdated":"2026-10-19T09:00:46.990Z","assignerShortName":"Linux","assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateReserved":"2026-09-11T19:38:34.796Z"},"containers":{"cna":{"title":"bpf: Reject load-acquire from pointers requiring fault protection","descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\nbpf: Reject load-acquire from pointers requiring fault protection\n\nA BPF_LOAD_ACQ is not rewritten to a BPF_PROBE_MEM load by the verifier,\nunlike a regular BPF_LDX, so the JIT emits a plain load with no exception\ntable entry and a fault panics the kernel instead of being handled.\n\nReject the source pointer types that a BPF_LDX would have had that fault\nprotection applied to, i.e. the ones bpf_convert_ctx_accesses() turns\ninto BPF_PROBE_MEM: a bare PTR_TO_BTF_ID, PTR_TO_BTF_ID | PTR_UNTRUSTED,\nPTR_TO_BTF_ID | MEM_ALLOC | PTR_UNTRUSTED and PTR_TO_MEM | MEM_RDONLY |\nPTR_UNTRUSTED.\n\nThis is reachable e.g. by loading ->mm out of a trusted task_struct\nyields an untrusted pointer to mm_struct, and it is NULL for a kernel\nthread:\n\n  [...]\n  SEC(\"tp_btf/sched_switch\")\n  int BPF_PROG(demo, bool preempt, struct task_struct *prev,\n               struct task_struct *next)\n  {\n      struct mm_struct *mm = next->mm;  /* untrusted */\n\n      out_ldx = (__u64)mm->pgd;         /* BPF_LDX      */\n      out_acq = load_acquire(&mm->pgd); /* BPF_LOAD_ACQ */\n      return 0;\n  }\n  [...]\n\nBoth dereference the same pointer, but only the BPF_LDX is protected\n(x86-64 JIT, jump targets shown prog-relative):\n\n  [...]\n  ; out_ldx = (__u64)mm->pgd;\n  17:   movq    $-10485760, %r10\n  1e:   movq    %rsi, %r11\n  21:   addq    $184, %r11\n  28:   subq    %r10, %r11\n  2b:   movabsq $140737498841088, %r10\n  35:   cmpq    %r10, %r11\n  38:   ja      0x3e                 <-- kernel addr?\n  3a:   xorl    %edi, %edi           <-- no: dst = 0, skip the load\n  3c:   jmp     0x45\n  3e:   movq    184(%rsi), %rdi      <-- yes: load + extable entry\n  [...]\n  ; load_acquire(&mm->pgd)\n  53:\tmovq    %rsi, %rdi\n  56:\tmovq    184(%rdi), %rax       <-- no check, no extable entry\n  [...]\n\nNote that BPF_PROBE_MEM is not visible in a bpftool xlated dump, as\nbpf_insn_prepare_dump() rewrites it back to BPF_MEM.\n\nA PTR_TRUSTED pointer is deliberately not on the list. Such a load is\nnot converted either, but it does not need to be, since the pointer is\nguaranteed live, so load-acquire from it stays allowed.\n\nThe check is gated on BPF_LOAD_ACQ so that atomic RMW and store-release\nerror messages are unchanged; writes (RMW / store-release) to such\npointers are already rejected elsewhere, so only load-acquire needs this."}],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"880442305a3908589bf4d6fc1d79edb577ee497c","status":"affected","lessThan":"c4c8de3bf48d3756ab0f910fe5cc4937d70efdcd","versionType":"git"},{"version":"880442305a3908589bf4d6fc1d79edb577ee497c","status":"affected","lessThan":"5f8ade6e9b7931fc9697394f1b2c4ae833f5ac18","versionType":"git"},{"version":"880442305a3908589bf4d6fc1d79edb577ee497c","status":"affected","lessThan":"7db0a00445f1a40bacfe9b747405c11cb5f10fc9","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["kernel/bpf/verifier.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"6.15","status":"affected"},{"version":"0","status":"unaffected","lessThan":"6.15","versionType":"semver"},{"version":"6.18.52","status":"unaffected","lessThanOrEqual":"6.18.*","versionType":"semver"},{"version":"7.2.6","status":"unaffected","lessThanOrEqual":"7.2.*","versionType":"semver"},{"version":"7.3","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["kernel/bpf/verifier.c"]}],"references":[{"url":"https://git.kernel.org/stable/c/c4c8de3bf48d3756ab0f910fe5cc4937d70efdcd"},{"url":"https://git.kernel.org/stable/c/5f8ade6e9b7931fc9697394f1b2c4ae833f5ac18"},{"url":"https://git.kernel.org/stable/c/7db0a00445f1a40bacfe9b747405c11cb5f10fc9"}],"providerMetadata":{"shortName":"Linux","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateUpdated":"2026-10-19T09:00:46.990Z"},"cpeApplicability":[{"nodes":[{"operator":"OR","negate":false,"cpeMatch":[{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.15","versionEndExcluding":"6.18.52"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.15","versionEndExcluding":"7.2.6"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.15","versionEndExcluding":"7.3"}]}]}],"x_generator":{"engine":"bippy-1.2.0"}}}}}