264 lines
14 KiB
JSON
264 lines
14 KiB
JSON
{
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"dataType": "CVE_RECORD",
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"dataVersion": "5.2",
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"cveMetadata": {
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"cveId": "CVE-2026-89696",
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"assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
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"state": "PUBLISHED",
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"assignerShortName": "Linux",
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"dateReserved": "2026-09-11T19:38:34.750Z",
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"datePublished": "2026-09-11T19:46:15.030Z",
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"dateUpdated": "2026-10-19T08:51:09.479Z"
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},
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"containers": {
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"cna": {
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"providerMetadata": {
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"orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
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"shortName": "Linux",
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"dateUpdated": "2026-10-19T08:51:09.479Z"
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},
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"descriptions": [
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{
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"lang": "en",
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"value": "In the Linux kernel, the following vulnerability has been resolved:\n\nnfsd: block non-SAVEFH ops after FOREIGN PUTFH to prevent NULL deref\n\nWhen CONFIG_NFSD_V4_2_INTER_SSC is enabled, nfsd4_putfh() can return\nsuccess with fh_dentry and fh_export both NULL if fh_verify() returns\nnfserr_stale and putfh->no_verify is true. The NFSD4_FH_FOREIGN flag\nis set, but the compound dispatch loop only uses this flag to bypass\nthe nfserr_nofilehandle check -- it does not prevent subsequent ops\nfrom running with a NULL fh_dentry.\n\nA remote client can exploit this by crafting a COMPOUND that includes\nan inter-SSC COPY (which causes check_if_stalefh_allowed() to set\nno_verify=true on the saved PUTFH) with an additional op inserted\nbetween the source PUTFH and SAVEFH. For example, SETATTR calls\nfh_want_write() which dereferences fh_export->ex_path.mnt without\ncalling fh_verify() first, causing a NULL pointer dereference in the\nnfsd kthread.\n\nFix this by gating the dispatch loop: when NFSD4_FH_FOREIGN is set\nand fh_dentry is NULL, only OP_SAVEFH (needed for the inter-SSC flow)\nand ops with ALLOWED_WITHOUT_FH (which don't need a resolved\nfilehandle) may proceed. All other ops receive nfserr_stale, per\nRFC 7862 Section 15.2.3 which specifies that foreign filehandle\nvalidation is deferred to the consuming operation and NFS4ERR_STALE\nreturned at that point."
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}
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],
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"metrics": [
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{
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"cvssV3_1": {
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"version": "3.1",
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"vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H",
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"baseScore": 7.5,
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"baseSeverity": "HIGH"
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},
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"scenarios": [
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{
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"lang": "en",
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"value": "AV:N - The bug is in nfsd NFSv4 COMPOUND dispatch and is triggered by a crafted NFSv4.2 COMPOUND over TCP/2049 (PUTFH of a stale fh, then SETATTR, with an inter-SSC COPY in the same compound). No local access is required.\nAC:L - After EXCHANGE_ID/CREATE_SESSION, the attacker fully controls the compound that marks the source PUTFH no_verify and inserts SETATTR before SAVEFH, so fh_want_write hits NULL fh_export deterministically with no race or layout dependency.\nPR:N - AUTH_SYS (the usual nfsd configuration) verifies no secret; a client just asserts a UID to create a session. SETATTR then runs on the FOREIGN fh without fh_verify, so no export access check or other credential gate is reached.\nUI:N - The attacker sends the COMPOUND directly to nfsd; no administrator or victim user action is required at exploitation time.\nS:U - The NULL dereference oopses the nfsd kthread in the host kernel's own authority and does not cross a VM, IOMMU, or sandbox boundary.\nC:N - After the stale FOREIGN PUTFH, fh_export and fh_dentry are NULL rather than dangling or attacker-controlled, so the fault is on the first load of fh_export->ex_path.mnt with no disclosure.\nI:N - This is a pure NULL pointer dereference in fh_want_write with no write to attacker-influenced memory and no control-flow hijack primitive.\nA:H - The NULL dereference oopses the nfsd kthread and can be replayed to exhaust nfsd threads, denying NFS service; with panic_on_oops it panics the host."
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}
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]
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}
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],
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"affected": [
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{
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"product": "Linux",
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"vendor": "Linux",
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"defaultStatus": "unaffected",
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"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
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"programFiles": [
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"fs/nfsd/nfs4proc.c"
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],
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"versions": [
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{
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"version": "b9e8638e3d9ed8334f1f7071e081860aac37e83e",
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"lessThan": "ffdc844e673d2bcb2af8c8c3eef8cdea59d0bf32",
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"status": "affected",
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"versionType": "git"
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},
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{
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"version": "b9e8638e3d9ed8334f1f7071e081860aac37e83e",
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"lessThan": "00c84f4eec715e501efc080a5670114189e42507",
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"status": "affected",
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},
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{
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"lessThan": "2d9846fd1c767920fddd4bde30eb35cd2969df13",
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"status": "affected",
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{
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"version": "b9e8638e3d9ed8334f1f7071e081860aac37e83e",
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"lessThan": "977e6f006a7a3ffc4216ae6034f768f8de6fd138",
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"status": "affected",
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},
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{
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"version": "b9e8638e3d9ed8334f1f7071e081860aac37e83e",
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"lessThan": "35f248bd40b47b229d4999581df45b97daadd977",
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"status": "affected",
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"versionType": "git"
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},
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{
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"version": "b9e8638e3d9ed8334f1f7071e081860aac37e83e",
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"lessThan": "311f7d926630940650447cbd1c932b076b40a6c4",
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"status": "affected",
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"versionType": "git"
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},
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{
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"version": "b9e8638e3d9ed8334f1f7071e081860aac37e83e",
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"lessThan": "bf4d338dc8625d70c7f2cb0657d66851a7ac9154",
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"status": "affected",
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"versionType": "git"
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},
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{
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"version": "b9e8638e3d9ed8334f1f7071e081860aac37e83e",
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"lessThan": "c59738a00aa51b16adc1b5ceb7c80877168efb4d",
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"status": "affected",
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"versionType": "git"
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}
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]
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},
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{
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"product": "Linux",
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"vendor": "Linux",
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"defaultStatus": "affected",
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"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
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"programFiles": [
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"fs/nfsd/nfs4proc.c"
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],
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"versions": [
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{
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"version": "5.6",
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"status": "affected"
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},
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{
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"version": "0",
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"lessThan": "5.6",
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"status": "unaffected",
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"versionType": "semver"
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},
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{
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"version": "5.10.270",
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"lessThanOrEqual": "5.10.*",
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"status": "unaffected",
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"versionType": "semver"
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},
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{
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"version": "5.15.221",
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"lessThanOrEqual": "5.15.*",
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"status": "unaffected",
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"versionType": "semver"
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},
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{
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"version": "6.1.188",
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"lessThanOrEqual": "6.1.*",
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"status": "unaffected",
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"versionType": "semver"
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},
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{
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"version": "6.6.157",
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"lessThanOrEqual": "6.6.*",
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"status": "unaffected",
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"versionType": "semver"
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},
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{
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"version": "6.12.109",
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"lessThanOrEqual": "6.12.*",
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"status": "unaffected",
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"versionType": "semver"
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},
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{
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"version": "6.18.50",
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"lessThanOrEqual": "6.18.*",
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"status": "unaffected",
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"versionType": "semver"
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},
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{
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"version": "7.2.4",
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"lessThanOrEqual": "7.2.*",
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"status": "unaffected",
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"versionType": "semver"
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},
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{
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"version": "7.3",
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"lessThanOrEqual": "*",
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"status": "unaffected",
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"versionType": "original_commit_for_fix"
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}
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]
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}
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],
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"cpeApplicability": [
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{
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"nodes": [
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"operator": "OR",
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"negate": false,
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"cpeMatch": [
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"references": [
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{
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"url": "https://git.kernel.org/stable/c/ffdc844e673d2bcb2af8c8c3eef8cdea59d0bf32"
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},
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{
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"url": "https://git.kernel.org/stable/c/00c84f4eec715e501efc080a5670114189e42507"
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},
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{
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"url": "https://git.kernel.org/stable/c/2d9846fd1c767920fddd4bde30eb35cd2969df13"
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},
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{
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"url": "https://git.kernel.org/stable/c/977e6f006a7a3ffc4216ae6034f768f8de6fd138"
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},
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{
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"url": "https://git.kernel.org/stable/c/35f248bd40b47b229d4999581df45b97daadd977"
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},
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{
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"url": "https://git.kernel.org/stable/c/311f7d926630940650447cbd1c932b076b40a6c4"
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},
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{
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"url": "https://git.kernel.org/stable/c/bf4d338dc8625d70c7f2cb0657d66851a7ac9154"
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},
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{
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"url": "https://git.kernel.org/stable/c/c59738a00aa51b16adc1b5ceb7c80877168efb4d"
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}
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],
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"title": "nfsd: block non-SAVEFH ops after FOREIGN PUTFH to prevent NULL deref",
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"x_generator": {
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"engine": "bippy-1.2.0"
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} |