{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-93125","assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","state":"PUBLISHED","assignerShortName":"Linux","dateReserved":"2026-09-17T16:02:15.087Z","datePublished":"2026-09-17T16:11:29.895Z","dateUpdated":"2026-09-18T17:56:05.805Z"},"containers":{"cna":{"providerMetadata":{"orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","shortName":"Linux","dateUpdated":"2026-09-18T17:56:05.805Z"},"descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\nbpf: Reject rdonly/rdwr_buf_size kfunc arguments that exceed u32 max\n\ncheck_kfunc_args() detects a kfunc argument named rdonly_buf_size or\nrdwr_buf_size and stores reg->var_off.value into meta->r0_size, a u64,\nand does not bound it. check_kfunc_call() later copies that value into\nthe returned register's mem_size field:\n\n  meta->r0_size = reg->var_off.value;\n  ...\n  regs[BPF_REG_0].mem_size = meta.r0_size;\n\nregs[BPF_REG_0].mem_size is u32. A constant whose upper 32 bits are set\ngets truncated instead of causing a load-time rejection, so the verifier\nrecords a PTR_TO_MEM register with an approximately 4 GiB mem_size for\nwhatever allocation the kfunc returned. A later access check against\nthat register uses the truncated, wrong bound.\n\nReject rdonly_buf_size/rdwr_buf_size values that exceed U32_MAX at the\npoint meta->r0_size is set."}],"metrics":[{"cvssV3_1":{"version":"3.1","vectorString":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","baseScore":7.8,"baseSeverity":"HIGH"},"scenarios":[{"lang":"en","value":"AV:L - check_kfunc_args() takes the oversized rdonly_buf_size/rdwr_buf_size from the BPF program's own constant (reg->var_off.value) on the local bpf(BPF_PROG_LOAD) path (bpf_prog_load → bpf_check → check_kfunc_call). That immediate is not a field of a received packet or a ksmbd/nfsd message.\nAC:L - The attacker picks a 64-bit immediate with upper bits set (e.g. ~0ULL as in hid_rdesc_fixup_get_data_overflow) as the rdonly_buf_size/rdwr_buf_size argument; tnum_is_const succeeds and regs[BPF_REG_0].mem_size = meta.r0_size truncates deterministically, with no race or layout outside their control.\nPR:L - do_check_common() rejects BPF_PSEUDO_KFUNC_CALL unless env->bpf_capable, which bpf_check() sets from bpf_token_capable(token, CAP_BPF). CAP_BPF is a reduced capability and is delegable into a user namespace via a BPF token, so init-namespace root is not required.\nUI:N - The attacker loads the crafted program with bpf(BPF_PROG_LOAD) and runs it themselves via BPF_PROG_TEST_RUN or by attaching their own HID-BPF/io_uring struct_ops. No separate victim action such as mounting an image is required.\nS:U - The truncated PTR_TO_MEM mem_size lets the verified program read and write host kernel memory, which is a standard kernel privilege escalation in the same authority. It does not cross a KVM/Xen, IOMMU, or guest-to-host boundary.\nC:H - check_kfunc_call() copies the truncated r0_size into a PTR_TO_MEM register, so check_mem_region_access() allows loads of up to ~4 GiB. bpf_kfunc_call_test_get_rdonly_mem takes const int rdonly_buf_size: a value such as 0x1FFFFFFFF becomes -1, the size > 8 check fails open, and the 8-byte prog_test_ref_kfunc is treated as a 4 GiB readable buffer.\nI:H - rdwr_buf_size kfuncs (bpf_kfunc_call_test_get_rdwr_mem, hid_bpf_get_data, bpf_io_uring_get_region) mark R0 as writable PTR_TO_MEM. The same truncated mem_size lets check_mem_region_access() accept stores past the real object, which is an arbitrary kernel write.\nA:H - Those verifier-allowed out-of-bounds loads and stores overrun the kfunc's actual object (prog_test_struct from get_mem, hid_bpf_get_data's ctx_kern->data, or an io_uring mapped region) and can oops or panic the kernel."}]}],"affected":[{"product":"Linux","vendor":"Linux","defaultStatus":"unaffected","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["kernel/bpf/verifier.c"],"versions":[{"version":"eb1f7f71c126c8fd50ea81af98f97c4b581ea4ae","lessThan":"56a3846830ac95a472297d0cbba75cbff29540bb","status":"affected","versionType":"git"},{"version":"eb1f7f71c126c8fd50ea81af98f97c4b581ea4ae","lessThan":"2aaf67f0516fde29620d0edfc29c01b9ea7ad430","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/verifier.c"],"versions":[{"version":"6.1","status":"affected"},{"version":"0","lessThan":"6.1","status":"unaffected","versionType":"semver"},{"version":"7.2.6","lessThanOrEqual":"7.2.*","status":"unaffected","versionType":"semver"},{"version":"7.3-rc1","lessThanOrEqual":"*","status":"unaffected","versionType":"original_commit_for_fix"}]}],"cpeApplicability":[{"nodes":[{"operator":"OR","negate":false,"cpeMatch":[{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.1","versionEndExcluding":"7.2.6"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.1","versionEndExcluding":"7.3-rc1"}]}]}],"references":[{"url":"https://git.kernel.org/stable/c/56a3846830ac95a472297d0cbba75cbff29540bb"},{"url":"https://git.kernel.org/stable/c/2aaf67f0516fde29620d0edfc29c01b9ea7ad430"}],"title":"bpf: Reject rdonly/rdwr_buf_size kfunc arguments that exceed u32 max","x_generator":{"engine":"bippy-1.2.0"}}}}