CVE-2025-40246
Full vulnerability record from the local CVENow database.
Description
In the Linux kernel, the following vulnerability has been resolved: xfs: fix out of bounds memory read error in symlink repair xfs/286 produced this report on my test fleet: ================================================================== BUG: KFENCE: out-of-bounds read in memcpy_orig+0x54/0x110 Out-of-bounds read at 0xffff88843fe9e038 (184B right of kfence-#184): memcpy_orig+0x54/0x110 xrep_symlink_salvage_inline+0xb3/0xf0 [xfs] xrep_symlink_salvage+0x100/0x110 [xfs] xrep_symlink+0x2e/0x80 [xfs] xrep_attempt+0x61/0x1f0 [xfs] xfs_scrub_metadata+0x34f/0x5c0 [xfs] xfs_ioc_scrubv_metadata+0x387/0x560 [xfs] xfs_file_ioctl+0xe23/0x10e0 [xfs] __x64_sys_ioctl+0x76/0xc0 do_syscall_64+0x4e/0x1e0 entry_SYSCALL_64_after_hwframe+0x4b/0x53 kfence-#184: 0xffff88843fe9df80-0xffff88843fe9dfea, size=107, cache=kmalloc-128 allocated by task 3470 on cpu 1 at 263329.131592s (192823.508886s ago): xfs_init_local_fork+0x79/0xe0 [xfs] xfs_iformat_local+0xa4/0x170 [xfs] xfs_iformat_data_fork+0x148/0x180 [xfs] xfs_inode_from_disk+0x2cd/0x480 [xfs] xfs_iget+0x450/0xd60 [xfs] xfs_bulkstat_one_int+0x6b/0x510 [xfs] xfs_bulkstat_iwalk+0x1e/0x30 [xfs] xfs_iwalk_ag_recs+0xdf/0x150 [xfs] xfs_iwalk_run_callbacks+0xb9/0x190 [xfs] xfs_iwalk_ag+0x1dc/0x2f0 [xfs] xfs_iwalk_args.constprop.0+0x6a/0x120 [xfs] xfs_iwalk+0xa4/0xd0 [xfs] xfs_bulkstat+0xfa/0x170 [xfs] xfs_ioc_fsbulkstat.isra.0+0x13a/0x230 [xfs] xfs_file_ioctl+0xbf2/0x10e0 [xfs] __x64_sys_ioctl+0x76/0xc0 do_syscall_64+0x4e/0x1e0 entry_SYSCALL_64_after_hwframe+0x4b/0x53 CPU: 1 UID: 0 PID: 1300113 Comm: xfs_scrub Not tainted 6.18.0-rc4-djwx #rc4 PREEMPT(lazy) 3d744dd94e92690f00a04398d2bd8631dcef1954 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.16.0-4.module+el8.8.0+21164+ed375313 04/01/2014 ================================================================== On further analysis, I realized that the second parameter to min() is not correct. xfs_ifork::if_bytes is the size of the xfs_ifork::if_data buffer. if_bytes can be smaller than the data fork size because: (a) the forkoff code tries to keep the data area as large as possible (b) for symbolic links, if_bytes is the ondisk file size + 1 (c) forkoff is always a multiple of 8. Case in point: for a single-byte symlink target, forkoff will be 8 but the buffer will only be 2 bytes long. In other words, the logic here is wrong and we walk off the end of the incore buffer. Fix that.
View original CVE JSON
{
"id": "CVE-2025-40246",
"sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"published": "2025-12-04T16:16:17.970",
"lastModified": "2026-10-19T19:10:00.130",
"vulnStatus": "Deferred",
"cveTags": [],
"descriptions": [
{
"lang": "en",
"value": "In the Linux kernel, the following vulnerability has been resolved:\n\nxfs: fix out of bounds memory read error in symlink repair\n\nxfs/286 produced this report on my test fleet:\n\n ==================================================================\n BUG: KFENCE: out-of-bounds read in memcpy_orig+0x54/0x110\n\n Out-of-bounds read at 0xffff88843fe9e038 (184B right of kfence-#184):\n memcpy_orig+0x54/0x110\n xrep_symlink_salvage_inline+0xb3/0xf0 [xfs]\n xrep_symlink_salvage+0x100/0x110 [xfs]\n xrep_symlink+0x2e/0x80 [xfs]\n xrep_attempt+0x61/0x1f0 [xfs]\n xfs_scrub_metadata+0x34f/0x5c0 [xfs]\n xfs_ioc_scrubv_metadata+0x387/0x560 [xfs]\n xfs_file_ioctl+0xe23/0x10e0 [xfs]\n __x64_sys_ioctl+0x76/0xc0\n do_syscall_64+0x4e/0x1e0\n entry_SYSCALL_64_after_hwframe+0x4b/0x53\n\n kfence-#184: 0xffff88843fe9df80-0xffff88843fe9dfea, size=107, cache=kmalloc-128\n\n allocated by task 3470 on cpu 1 at 263329.131592s (192823.508886s ago):\n xfs_init_local_fork+0x79/0xe0 [xfs]\n xfs_iformat_local+0xa4/0x170 [xfs]\n xfs_iformat_data_fork+0x148/0x180 [xfs]\n xfs_inode_from_disk+0x2cd/0x480 [xfs]\n xfs_iget+0x450/0xd60 [xfs]\n xfs_bulkstat_one_int+0x6b/0x510 [xfs]\n xfs_bulkstat_iwalk+0x1e/0x30 [xfs]\n xfs_iwalk_ag_recs+0xdf/0x150 [xfs]\n xfs_iwalk_run_callbacks+0xb9/0x190 [xfs]\n xfs_iwalk_ag+0x1dc/0x2f0 [xfs]\n xfs_iwalk_args.constprop.0+0x6a/0x120 [xfs]\n xfs_iwalk+0xa4/0xd0 [xfs]\n xfs_bulkstat+0xfa/0x170 [xfs]\n xfs_ioc_fsbulkstat.isra.0+0x13a/0x230 [xfs]\n xfs_file_ioctl+0xbf2/0x10e0 [xfs]\n __x64_sys_ioctl+0x76/0xc0\n do_syscall_64+0x4e/0x1e0\n entry_SYSCALL_64_after_hwframe+0x4b/0x53\n\n CPU: 1 UID: 0 PID: 1300113 Comm: xfs_scrub Not tainted 6.18.0-rc4-djwx #rc4 PREEMPT(lazy) 3d744dd94e92690f00a04398d2bd8631dcef1954\n Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.16.0-4.module+el8.8.0+21164+ed375313 04/01/2014\n ==================================================================\n\nOn further analysis, I realized that the second parameter to min() is\nnot correct. xfs_ifork::if_bytes is the size of the xfs_ifork::if_data\nbuffer. if_bytes can be smaller than the data fork size because:\n\n(a) the forkoff code tries to keep the data area as large as possible\n(b) for symbolic links, if_bytes is the ondisk file size + 1\n(c) forkoff is always a multiple of 8.\n\nCase in point: for a single-byte symlink target, forkoff will be\n8 but the buffer will only be 2 bytes long.\n\nIn other words, the logic here is wrong and we walk off the end of the\nincore buffer. Fix that."
},
{
"lang": "es",
"value": "En el kernel de Linux, la siguiente vulnerabilidad ha sido resuelta:\n\nxfs: solución de error de lectura de memoria fuera de límites en la reparación de enlaces simbólicos\n\nxfs/286 produjo este informe en mi flota de pruebas:\n\n ==================================================================\n ERROR: KFENCE: lectura fuera de límites en memcpy_orig+0x54/0x110\n\n Lectura fuera de límites en 0xffff88843fe9e038 (184B a la derecha de kfence-#184):\n memcpy_orig+0x54/0x110\n xrep_symlink_salvage_inline+0xb3/0xf0 [xfs]\n xrep_symlink_salvage+0x100/0x110 [xfs]\n xrep_symlink+0x2e/0x80 [xfs]\n xrep_attempt+0x61/0x1f0 [xfs]\n xfs_scrub_metadata+0x34f/0x5c0 [xfs]\n xfs_ioc_scrubv_metadata+0x387/0x560 [xfs]\n xfs_file_ioctl+0xe23/0x10e0 [xfs]\n __x64_sys_ioctl+0x76/0xc0\n do_syscall_64+0x4e/0x1e0\n entry_SYSCALL_64_after_hwframe+0x4b/0x53\n\n kfence-#184: 0xffff88843fe9df80-0xffff88843fe9dfea, tamaño=107, caché=kmalloc-128\n\n asignado por la tarea 3470 en la CPU 1 a las 263329.131592s (hace 192823.508886s):\n xfs_init_local_fork+0x79/0xe0 [xfs]\n xfs_iformat_local+0xa4/0x170 [xfs]\n xfs_iformat_data_fork+0x148/0x180 [xfs]\n xfs_inode_from_disk+0x2cd/0x480 [xfs]\n xfs_iget+0x450/0xd60 [xfs]\n xfs_bulkstat_one_int+0x6b/0x510 [xfs]\n xfs_bulkstat_iwalk+0x1e/0x30 [xfs]\n xfs_iwalk_ag_recs+0xdf/0x150 [xfs]\n xfs_iwalk_run_callbacks+0xb9/0x190 [xfs]\n xfs_iwalk_ag+0x1dc/0x2f0 [xfs]\n xfs_iwalk_args.constprop.0+0x6a/0x120 [xfs]\n xfs_iwalk+0xa4/0xd0 [xfs]\n xfs_bulkstat+0xfa/0x170 [xfs]\n xfs_ioc_fsbulkstat.isra.0+0x13a/0x230 [xfs]\n xfs_file_ioctl+0xbf2/0x10e0 [xfs]\n __x64_sys_ioctl+0x76/0xc0\n do_syscall_64+0x4e/0x1e0\n entry_SYSCALL_64_after_hwframe+0x4b/0x53\n\n CPU: 1 UID: 0 PID: 1300113 Comm: xfs_scrub No contaminado 6.18.0-rc4-djwx #rc4 PREEMPT(lazy) 3d744dd94e92690f00a04398d2bd8631dcef1954\n Nombre del hardware: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.16.0-4.module+el8.8.0+21164+ed375313 04/01/2014\n ==================================================================\n\nTras un análisis adicional, me di cuenta de que el segundo parámetro de min() no es correcto. xfs_ifork::if_bytes es el tamaño del búfer xfs_ifork::if_data. if_bytes puede ser menor que el tamaño del data fork porque:\n\n(a) el código forkoff intenta mantener el área de datos lo más grande posible\n(b) para enlaces simbólicos, if_bytes es el tamaño del archivo en disco + 1\n(c) forkoff es siempre un múltiplo de 8.\n\nUn ejemplo claro: para un objetivo de enlace simbólico de un solo byte, forkoff será 8 pero el búfer solo tendrá 2 bytes de longitud.\n\nEn otras palabras, la lógica aquí es incorrecta y nos salimos del final del búfer en memoria. Corregir eso."
}
],
"affected": [
{
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"affectedData": [
{
"vendor": "Linux",
"product": "Linux",
"defaultStatus": "unaffected",
"programFiles": [
"fs/xfs/scrub/symlink_repair.c"
],
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"versions": [
{
"version": "2651923d8d8db00a57665822f017fa7c76758044",
"lessThan": "7c2d68e091584149fe89bcbaf9b99b3162d46ee7",
"versionType": "git",
"status": "affected"
},
{
"version": "2651923d8d8db00a57665822f017fa7c76758044",
"lessThan": "81a8685cac4bf081c93a7df591644f4f80240bb9",
"versionType": "git",
"status": "affected"
},
{
"version": "2651923d8d8db00a57665822f017fa7c76758044",
"lessThan": "678e1cc2f482e0985a0613ab4a5bf89c497e5acc",
"versionType": "git",
"status": "affected"
}
]
},
{
"vendor": "Linux",
"product": "Linux",
"defaultStatus": "affected",
"programFiles": [
"fs/xfs/scrub/symlink_repair.c"
],
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"versions": [
{
"version": "6.10",
"status": "affected"
},
{
"version": "0",
"lessThan": "6.10",
"versionType": "semver",
"status": "unaffected"
},
{
"version": "6.12.60",
"lessThanOrEqual": "6.12.*",
"versionType": "semver",
"status": "unaffected"
},
{
"version": "6.17.10",
"lessThanOrEqual": "6.17.*",
"versionType": "semver",
"status": "unaffected"
},
{
"version": "6.18",
"lessThanOrEqual": "*",
"versionType": "original_commit_for_fix",
"status": "unaffected"
}
]
}
]
}
],
"metrics": {},
"references": [
{
"url": "https://git.kernel.org/stable/c/678e1cc2f482e0985a0613ab4a5bf89c497e5acc",
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
},
{
"url": "https://git.kernel.org/stable/c/7c2d68e091584149fe89bcbaf9b99b3162d46ee7",
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
},
{
"url": "https://git.kernel.org/stable/c/81a8685cac4bf081c93a7df591644f4f80240bb9",
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
}
]
}