184 lines
11 KiB
JSON
184 lines
11 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-2026-98975",
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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": "2026-09-25T10:25:14.383Z",
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"datePublished": "2026-10-23T12:19:48.379Z",
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"dateUpdated": "2026-10-24T14:09:45.210Z"
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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": "2026-10-24T14:09:45.210Z"
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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\nxfs: stop exchanging reflink flags when exchanging mappings\n\nWhen an exchange covers both files from offset 0 to i_disk_size,\nxmi_can_exchange_reflink_flags() assumes every mapping moved and hands\nthe reflink flag over to the other file.\n\nThat assumption is wrong. A file can still own shared blocks past\ni_disk_size, e.g. after EXCHANGE_RANGE_TO_EOF sets a smaller size\nwithout unmapping anything. The flag is cleared anyway, and the next\nwrite to such a block happens in place instead of CoW, corrupting the\nother file that shares it.\n\nCommit a23eca88448e (\"xfs: fix exchange-range reflink flag clearing\nissue with INO1_WRITTEN\") fixed one instance of this. Rather than add\nanother special case, stop moving the flags.\nxfs_exchmaps_ensure_reflink() already sets the flag on both inodes\nbefore the exchange, so both just keep it.\n\nNothing sets CLEAR_INO{1,2}_REFLINK anymore. Intents logged by older\nkernels may still carry them; recovery already masks them off, so they\nstay in the log format mask and are ignored.\n\nXFS_IOC_SWAPEXT has the same problem: it moves the reflink flag from\none inode to the other along with the extents. Just removing that is\nnot enough here: the exchange path flags both inodes up front in\nxfs_exchmaps_ensure_reflink(), but swapext has no such step, so the\ninode receiving the shared extents would be left without the flag.\nSet it on both inodes instead, and make sure both have a CoW fork,\nsince an inode with the reflink flag is expected to have one.\n\nThe flag now stays until FALLOC_FL_UNSHARE_RANGE, xfs_scrub, or a\ntruncate to zero removes 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:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
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"baseScore": 7.8,
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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:L - `ioctl(2)` runs `do_vfs_ioctl()`/`vfs_ioctl()` → `xfs_file_ioctl()` → `xfs_ioc_exchange_range()` → `xfs_exchange_mappings()` → patched `xfs_exchmaps_init_intent()`; all causal file descriptors, offsets, and flags are supplied locally.\nAC:L - On a reflink/exchange-range XFS, the attacker can clone a target block, use chosen `TO_EOF` offsets to strand it past `i_disk_size`, perform a full-range exchange so `xmi_can_exchange_reflink_flags()` clears the flag, and `pwrite` the shared block; no race or external event is required.\nPR:L - `xfs_exchange_range()` requires only read-write scratch-file descriptors and `remap_verify_area(..., true)`, with no `capable()` check; FICLONE requires only read access to the protected source and write access to an attacker-owned destination.\nUI:N - The attacker personally performs FICLONERANGE, the crafted `XFS_IOC_EXCHANGE_RANGE` operations, and the final `pwrite`; no victim must mount media, open a file, or take another action.\nS:U - `xfs_exchmaps_clear_reflink()` breaks CoW isolation between inodes on the same XFS host; using the resulting protected-file overwrite for root access is a standard local privilege escalation, not a VM, IOMMU, or other security-authority escape.\nC:H - The attacker can clone a readable SUID-root binary, then make the faulty non-CoW write alter its physical block without modifying its inode or clearing SUID metadata; executing the corrupted binary can yield root and unrestricted access to host-confidential data.\nI:H - After `xfs_exchmaps_clear_reflink()` removes the flag, `xfs_is_cow_inode()` is false and the iomap write path updates the still-shared block in place, permitting persistent attacker-controlled modification of readable protected files without write permission.\nA:H - The same in-place primitive can corrupt readable boot-critical executables, and overwriting a SUID-root binary can provide root control capable of stopping the host, supporting complete availability loss."
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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/xfs/libxfs/xfs_exchmaps.c",
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"fs/xfs/libxfs/xfs_log_format.h",
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"fs/xfs/xfs_bmap_util.c"
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],
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"versions": [
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{
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"version": "f0bc4d134b46607967bda1205ce3226a1bd95f42",
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"lessThan": "1fa2f3a7ef7ee0f2503a4b0afe24bc8c9d0820be",
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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": "f0bc4d134b46607967bda1205ce3226a1bd95f42",
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"lessThan": "7d3b9b2c9dc57f93f36c716ab752548cb4db9900",
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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": "f0bc4d134b46607967bda1205ce3226a1bd95f42",
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"lessThan": "4756c94260e69ce42612b8220c3614f02f7a11d5",
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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": "f0bc4d134b46607967bda1205ce3226a1bd95f42",
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"lessThan": "d84d6c1a7f1e2de9e601703a326a4c1b7b421943",
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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/xfs/libxfs/xfs_exchmaps.c",
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"fs/xfs/libxfs/xfs_log_format.h",
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"fs/xfs/xfs_bmap_util.c"
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],
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"versions": [
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{
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"version": "4.9",
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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": "4.9",
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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": "6.12.114",
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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": "6.18.57",
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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": "7.2.11",
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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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{
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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": "4.9",
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"versionEndExcluding": "6.12.114"
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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": "4.9",
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"versionEndExcluding": "6.18.57"
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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": "4.9",
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"versionEndExcluding": "7.2.11"
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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": "4.9",
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"versionEndExcluding": "7.3"
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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/1fa2f3a7ef7ee0f2503a4b0afe24bc8c9d0820be"
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},
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{
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"url": "https://git.kernel.org/stable/c/7d3b9b2c9dc57f93f36c716ab752548cb4db9900"
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},
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{
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"url": "https://git.kernel.org/stable/c/4756c94260e69ce42612b8220c3614f02f7a11d5"
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},
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{
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"url": "https://git.kernel.org/stable/c/d84d6c1a7f1e2de9e601703a326a4c1b7b421943"
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}
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],
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"title": "xfs: stop exchanging reflink flags when exchanging mappings",
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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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} |