{ "dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": { "cveId": "CVE-2023-53024", "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "state": "PUBLISHED", "assignerShortName": "Linux", "dateReserved": "2025-03-27T16:40:15.753Z", "datePublished": "2025-03-27T16:43:49.824Z", "dateUpdated": "2026-05-23T15:27:44.578Z" }, "containers": { "cna": { "providerMetadata": { "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "shortName": "Linux", "dateUpdated": "2026-05-23T15:27:44.578Z" }, "descriptions": [ { "lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nbpf: Fix pointer-leak due to insufficient speculative store bypass mitigation\n\nTo mitigate Spectre v4, 2039f26f3aca (\"bpf: Fix leakage due to\ninsufficient speculative store bypass mitigation\") inserts lfence\ninstructions after 1) initializing a stack slot and 2) spilling a\npointer to the stack.\n\nHowever, this does not cover cases where a stack slot is first\ninitialized with a pointer (subject to sanitization) but then\noverwritten with a scalar (not subject to sanitization because\nthe slot was already initialized). In this case, the second write\nmay be subject to speculative store bypass (SSB) creating a\nspeculative pointer-as-scalar type confusion. This allows the\nprogram to subsequently leak the numerical pointer value using,\nfor example, a branch-based cache side channel.\n\nTo fix this, also sanitize scalars if they write a stack slot\nthat previously contained a pointer. Assuming that pointer-spills\nare only generated by LLVM on register-pressure, the performance\nimpact on most real-world BPF programs should be small.\n\nThe following unprivileged BPF bytecode drafts a minimal exploit\nand the mitigation:\n\n [...]\n // r6 = 0 or 1 (skalar, unknown user input)\n // r7 = accessible ptr for side channel\n // r10 = frame pointer (fp), to be leaked\n //\n r9 = r10 # fp alias to encourage ssb\n *(u64 *)(r9 - 8) = r10 // fp[-8] = ptr, to be leaked\n // lfence added here because of pointer spill to stack.\n //\n // Ommitted: Dummy bpf_ringbuf_output() here to train alias predictor\n // for no r9-r10 dependency.\n //\n *(u64 *)(r10 - 8) = r6 // fp[-8] = scalar, overwrites ptr\n // 2039f26f3aca: no lfence added because stack slot was not STACK_INVALID,\n // store may be subject to SSB\n //\n // fix: also add an lfence when the slot contained a ptr\n //\n r8 = *(u64 *)(r9 - 8)\n // r8 = architecturally a scalar, speculatively a ptr\n //\n // leak ptr using branch-based cache side channel:\n r8 &= 1 // choose bit to leak\n if r8 == 0 goto SLOW // no mispredict\n // architecturally dead code if input r6 is 0,\n // only executes speculatively iff ptr bit is 1\n r8 = *(u64 *)(r7 + 0) # encode bit in cache (0: slow, 1: fast)\nSLOW:\n [...]\n\nAfter running this, the program can time the access to *(r7 + 0) to\ndetermine whether the chosen pointer bit was 0 or 1. Repeat this 64\ntimes to recover the whole address on amd64.\n\nIn summary, sanitization can only be skipped if one scalar is\noverwritten with another scalar. Scalar-confusion due to speculative\nstore bypass can not lead to invalid accesses because the pointer\nbounds deducted during verification are enforced using branchless\nlogic. See 979d63d50c0c (\"bpf: prevent out of bounds speculation on\npointer arithmetic\") for details.\n\nDo not make the mitigation depend on !env->allow_{uninit_stack,ptr_leaks}\nbecause speculative leaks are likely unexpected if these were enabled.\nFor example, leaking the address to a protected log file may be acceptable\nwhile disabling the mitigation might unintentionally leak the address\ninto the cached-state of a map that is accessible to unprivileged\nprocesses." } ], "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": "872968502114d68c21419cf7eb5ab97717e7b803", "lessThan": "aae109414a57ab4164218f36e2e4a17f027fcaaa", "status": "affected", "versionType": "git" }, { "version": "f5893af2704eb763eb982f01d573f5b19f06b623", "lessThan": "81b3374944d201872cfcf82730a7860f8e7c31dd", "status": "affected", "versionType": "git" }, { "version": "0e9280654aa482088ee6ef3deadef331f5ac5fb0", "lessThan": "da75dec7c6617bddad418159ffebcb133f008262", "status": "affected", "versionType": "git" }, { "version": "2039f26f3aca5b0e419b98f65dd36481337b86ee", "lessThan": "01bdcc73dbe7be3ad4d4ee9a59b71e42f461a528", "status": "affected", "versionType": "git" }, { "version": "2039f26f3aca5b0e419b98f65dd36481337b86ee", "lessThan": "b0c89ef025562161242a7c19b213bd6b272e93df", "status": "affected", "versionType": "git" }, { "version": "2039f26f3aca5b0e419b98f65dd36481337b86ee", "lessThan": "e4f4db47794c9f474b184ee1418f42e6a07412b6", "status": "affected", "versionType": "git" }, { "version": "0b27bdf02c400684225ee5ee99970bcbf5082282", "status": "affected", "versionType": "git" }, { "version": "4.19.207", "lessThan": "4.19.272", "status": "affected", "versionType": "semver" }, { "version": "5.4.146", "lessThan": "5.4.231", "status": "affected", "versionType": "semver" }, { "version": "5.10.56", "lessThan": "5.10.166", "status": "affected", "versionType": "semver" }, { "version": "5.13.8", "lessThan": "5.14", "status": "affected", "versionType": "semver" } ] }, { "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": "5.14", "status": "affected" }, { "version": "0", "lessThan": "5.14", "status": "unaffected", "versionType": "semver" }, { "version": "4.19.272", "lessThanOrEqual": "4.19.*", "status": "unaffected", "versionType": "semver" }, { "version": "5.4.231", "lessThanOrEqual": "5.4.*", "status": "unaffected", "versionType": "semver" }, { "version": "5.10.166", "lessThanOrEqual": "5.10.*", "status": "unaffected", "versionType": "semver" }, { "version": "5.15.91", "lessThanOrEqual": "5.15.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.1.9", "lessThanOrEqual": "6.1.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.2", "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": "4.19.207", "versionEndExcluding": "4.19.272" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.4.146", "versionEndExcluding": "5.4.231" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.10.56", "versionEndExcluding": "5.10.166" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.14", "versionEndExcluding": "5.15.91" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.14", "versionEndExcluding": "6.1.9" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.14", "versionEndExcluding": "6.2" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.13.8" } ] } ] } ], "references": [ { "url": "https://git.kernel.org/stable/c/aae109414a57ab4164218f36e2e4a17f027fcaaa" }, { "url": "https://git.kernel.org/stable/c/81b3374944d201872cfcf82730a7860f8e7c31dd" }, { "url": "https://git.kernel.org/stable/c/da75dec7c6617bddad418159ffebcb133f008262" }, { "url": "https://git.kernel.org/stable/c/01bdcc73dbe7be3ad4d4ee9a59b71e42f461a528" }, { "url": "https://git.kernel.org/stable/c/b0c89ef025562161242a7c19b213bd6b272e93df" }, { "url": "https://git.kernel.org/stable/c/e4f4db47794c9f474b184ee1418f42e6a07412b6" } ], "title": "bpf: Fix pointer-leak due to insufficient speculative store bypass mitigation", "x_generator": { "engine": "bippy-1.2.0" } } } }