172 lines
10 KiB
JSON
172 lines
10 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-2024-42256",
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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": "2024-07-30T07:40:12.257Z",
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"datePublished": "2024-08-08T08:49:15.813Z",
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"dateUpdated": "2026-08-05T11:36:06.795Z"
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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": "2026-08-05T11:36:06.795Z"
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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\ncifs: Fix server re-repick on subrequest retry\n\nWhen a subrequest is marked for needing retry, netfs will call\ncifs_prepare_write() which will make cifs repick the server for the op\nbefore renegotiating credits; it then calls cifs_issue_write() which\ninvokes smb2_async_writev() - which re-repicks the server.\n\nIf a different server is then selected, this causes the increment of\nserver->in_flight to happen against one record and the decrement to happen\nagainst another, leading to misaccounting.\n\nFix this by just removing the repick code in smb2_async_writev(). As this\nis only called from netfslib-driven code, cifs_prepare_write() should\nalways have been called first, and so server should never be NULL and the\npreparatory step is repeated in the event that we do a retry.\n\nThe problem manifests as a warning looking something like:\n\n WARNING: CPU: 4 PID: 72896 at fs/smb/client/smb2ops.c:97 smb2_add_credits+0x3f0/0x9e0 [cifs]\n ...\n RIP: 0010:smb2_add_credits+0x3f0/0x9e0 [cifs]\n ...\n smb2_writev_callback+0x334/0x560 [cifs]\n cifs_demultiplex_thread+0x77a/0x11b0 [cifs]\n kthread+0x187/0x1d0\n ret_from_fork+0x34/0x60\n ret_from_fork_asm+0x1a/0x30\n\nWhich may be triggered by a number of different xfstests running against an\nAzure server in multichannel mode. generic/249 seems the most repeatable,\nbut generic/215, generic/249 and generic/308 may also show it."
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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 trigger is the SMB write-retry path, and retries are dictated entirely by the remote SMB server's responses (`MID_REQUEST_SUBMITTED` on connection drop, or any `is_replayable_error()` status) reaching the client over TCP/445. A malicious/compromised server or an on-path attacker can force the retry at will.\nAC:L - The remote server can deterministically and repeatedly force write retries by returning replayable errors or dropping a channel's connection, and `cifs_pick_channel()` will select a different channel; there is no race or memory-layout condition outside the attacker's control.\nPR:N - The attacker is the remote SMB peer (or an on-path attacker) and needs no credentials or privileges on the victim client; the bug is hit during ordinary writeback on an already-established session.\nUI:N - The CIFS multichannel mount is a pre-existing environmental condition (fstab/autofs/cloud VM Azure Files mount), and at exploit time no victim action is required — ongoing background writeback is sufficient to enter the retry path.\nS:U - The credit and `in_flight` misaccounting is confined to the `TCP_Server_Info` structures of the client kernel's own CIFS session; no security boundary such as a VM or IOMMU domain is crossed.\nC:N - The defect is purely counter/credit misaccounting on the wrong channel record; tracing every use of `in_flight` and `server->credits` shows they index no memory and yield no read primitive or information disclosure.\nI:N - No memory is written out of bounds and no file data is altered — the write payload itself is transmitted correctly, only the per-channel credit and in-flight bookkeeping diverges.\nA:H - The bug reaches `WARN_ON_ONCE(server->in_flight == 0)` followed by an unsigned-integer underflow of `in_flight` to `UINT_MAX` (a kernel panic under `panic_on_warn`), and the permanently leaked credits on the original channel make `smb2_wait_mtu_credits()`'s untimed `wait_event_killable()` block forever, wedging the mount and stalling writeback indefinitely."
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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/smb/client/smb2pdu.c"
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],
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"versions": [
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{
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"version": "3ee1a1fc39819906f04d6c62c180e760cd3a689d",
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"lessThan": "b1d0a566769b6fb3795b5289fc1daf9e0638d97a",
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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": "3ee1a1fc39819906f04d6c62c180e760cd3a689d",
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"lessThan": "de40579b903883274fe203865f29d66b168b7236",
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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/smb/client/smb2pdu.c"
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],
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"versions": [
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{
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"version": "6.10",
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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": "6.10",
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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": "6.10.1",
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"lessThanOrEqual": "6.10.*",
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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": "6.11",
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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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{
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"operator": "OR",
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"negate": false,
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"cpeMatch": [
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{
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"vulnerable": true,
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"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
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"versionStartIncluding": "6.10",
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"versionEndExcluding": "6.10.1"
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},
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{
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"vulnerable": true,
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"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
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"versionStartIncluding": "6.10",
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"versionEndExcluding": "6.11"
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}
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]
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}
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]
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}
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],
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"references": [
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{
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"url": "https://git.kernel.org/stable/c/b1d0a566769b6fb3795b5289fc1daf9e0638d97a"
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},
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{
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"url": "https://git.kernel.org/stable/c/de40579b903883274fe203865f29d66b168b7236"
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}
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],
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"title": "cifs: Fix server re-repick on subrequest retry",
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"x_generator": {
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"engine": "bippy-1.2.0"
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}
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},
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"adp": [
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{
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"metrics": [
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{
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"other": {
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"type": "ssvc",
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"content": {
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"id": "CVE-2024-42256",
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"role": "CISA Coordinator",
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"options": [
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{
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"Exploitation": "none"
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},
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{
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"Automatable": "no"
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},
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{
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"Technical Impact": "partial"
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}
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],
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"version": "2.0.3",
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"timestamp": "2024-09-10T16:12:59.830016Z"
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}
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}
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}
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],
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"title": "CISA ADP Vulnrichment",
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"providerMetadata": {
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"orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
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"shortName": "CISA-ADP",
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"dateUpdated": "2024-09-11T17:34:30.018Z"
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}
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}
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}
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} |