CVE-2025-40237
Estado: AplazadaSin puntuar—
In the Linux kernel, the following vulnerability has been resolved:
fs/notify: call exportfs_encode_fid with s_umount
Calling intotify_show_fdinfo() on fd watching an overlayfs inode, while the overlayfs is being unmounted, can lead to dereferencing NULL ptr.
This issue was found by syzkaller.
Race Condition Diagram:
Thread 1 Thread 2 -------- --------
generic_shutdown_super() shrink_dcache_for_umount sb->s_root = NULL
Which then leads to:
<snip registers, unreliable trace>
IOW ovl_check_encode_origin derefs inode->i_sb->s_root, after it was set to NULL in the unmount path.
Leer descripción completaMostrar menos
Fix it by protecting calling exportfs_encode_fid() from show_mark_fhandle() with s_umount lock.
This form of fix was suggested by Amir in [1].
[1]: https://lore.kernel.org/all/CAOQ4uxhbDwhb+2Brs1UdkoF0a3NSdBAOQPNfEHjahrgoKJpLEw@mail.gmail.com/
Detalles técnicos trazas, registros y código del informe original
|
| vfs_read()
| inotify_fdinfo()
| * inode get from mark *
| show_mark_fhandle(m, inode)
| exportfs_encode_fid(inode, ..)
| ovl_encode_fh(inode, ..)
| ovl_check_encode_origin(inode)
| * deref i_sb->s_root *
|
|
v
fsnotify_sb_delete(sb)
[ 32.133461] Oops: general protection fault, probably for non-canonical address 0xdffffc0000000006: 0000 [#1] SMP DEBUG_PAGEALLOC KASAN NOPTI
[ 32.134438] KASAN: null-ptr-deref in range [0x0000000000000030-0x0000000000000037]
[ 32.135032] CPU: 1 UID: 0 PID: 4468 Comm: systemd-coredum Not tainted 6.17.0-rc6 #22 PREEMPT(none)
[ 32.143353] Call Trace:
[ 32.143732] ovl_encode_fh+0xd5/0x170
[ 32.144031] exportfs_encode_inode_fh+0x12f/0x300
[ 32.144425] show_mark_fhandle+0xbe/0x1f0
[ 32.145805] inotify_fdinfo+0x226/0x2d0
[ 32.146442] inotify_show_fdinfo+0x1c5/0x350
[ 32.147168] seq_show+0x530/0x6f0
[ 32.147449] seq_read_iter+0x503/0x12a0
[ 32.148419] seq_read+0x31f/0x410
[ 32.150714] vfs_read+0x1f0/0x9e0
[ 32.152297] ksys_read+0x125/0x240CVSS
NVD no ha asignado puntuación CVSS a esta CVE (habitual desde el cambio de política de abril de 2026).
Probabilidad de explotación (EPSS)
- Probabilidad de explotación en los próximos 30 días: 0.20%
- Percentil entre todas las CVEs puntuadas: 9
- Fecha de la puntuación: 6/10/2026
EPSS (Exploit Prediction Scoring System, de FIRST) estima la probabilidad de que una vulnerabilidad sea explotada en 30 días. Complementa a CVSS (impacto) y a CISA KEV (explotación confirmada).
Tecnologías afectadas (1)
⚠ Inferidas por IA a partir de la descripción — NVD aún no ha analizado esta CVE; no son CPE verificados.
Referencias
- https://git.kernel.org/stable/c/3f307a9f7a7a2822e38ac451b73e2244e7279496
- https://git.kernel.org/stable/c/950b604384fd75d62e860bec7135b2b62eb4d508
- https://git.kernel.org/stable/c/a7c4bb43bfdc2b9f06ee9d036028ed13a83df42a
- https://git.kernel.org/stable/c/bc1c6b803e14ea2b8f7e33b7164013f666ceb656
- https://git.kernel.org/stable/c/d1894bc542becb0fda61e7e513b09523cab44030
JSON original (NVD)
Mostrar
{
"id": "CVE-2025-40237",
"cveTags": [],
"metrics": {},
"affected": [
{
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"affectedData": [
{
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"product": "Linux",
"versions": [
{
"status": "affected",
"version": "a1a541fbfa7e97c1100144db34b57553d7164ce5",
"lessThan": "950b604384fd75d62e860bec7135b2b62eb4d508",
"versionType": "git"
},
{
"status": "affected",
"version": "f0c0ac84de17c37e6e84da65fb920f91dada55ad",
"lessThan": "bc1c6b803e14ea2b8f7e33b7164013f666ceb656",
"versionType": "git"
},
{
"status": "affected",
"version": "3c7c90274ae339e1ad443c9be1c67a20b80b9c76",
"lessThan": "3f307a9f7a7a2822e38ac451b73e2244e7279496",
"versionType": "git"
},
{
"status": "affected",
"version": "c45beebfde34aa71afbc48b2c54cdda623515037",
"lessThan": "d1894bc542becb0fda61e7e513b09523cab44030",
"versionType": "git"
},
{
"status": "affected",
"version": "c45beebfde34aa71afbc48b2c54cdda623515037",
"lessThan": "a7c4bb43bfdc2b9f06ee9d036028ed13a83df42a",
"versionType": "git"
},
{
"status": "affected",
"version": "6.6.72",
"lessThan": "6.6.73",
"versionType": "semver"
},
{
"status": "affected",
"version": "6.6.74",
"lessThan": "6.6.115",
"versionType": "semver"
},
{
"status": "affected",
"version": "6.12.10",
"lessThan": "6.12.56",
"versionType": "semver"
}
],
"programFiles": [
"fs/notify/fdinfo.c"
],
"defaultStatus": "unaffected"
},
{
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"product": "Linux",
"versions": [
{
"status": "affected",
"version": "6.13"
},
{
"status": "unaffected",
"version": "0",
"lessThan": "6.13",
"versionType": "semver"
},
{
"status": "unaffected",
"version": "6.6.73",
"versionType": "semver",
"lessThanOrEqual": "6.6.*"
},
{
"status": "unaffected",
"version": "6.6.115",
"versionType": "semver",
"lessThanOrEqual": "6.6.*"
},
{
"status": "unaffected",
"version": "6.12.56",
"versionType": "semver",
"lessThanOrEqual": "6.12.*"
},
{
"status": "unaffected",
"version": "6.17.6",
"versionType": "semver",
"lessThanOrEqual": "6.17.*"
},
{
"status": "unaffected",
"version": "6.18",
"versionType": "original_commit_for_fix",
"lessThanOrEqual": "*"
}
],
"programFiles": [
"fs/notify/fdinfo.c"
],
"defaultStatus": "affected"
}
]
}
],
"published": "2025-12-04T16:16:16.697",
"references": [
{
"url": "https://git.kernel.org/stable/c/3f307a9f7a7a2822e38ac451b73e2244e7279496",
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
},
{
"url": "https://git.kernel.org/stable/c/950b604384fd75d62e860bec7135b2b62eb4d508",
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
},
{
"url": "https://git.kernel.org/stable/c/a7c4bb43bfdc2b9f06ee9d036028ed13a83df42a",
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
},
{
"url": "https://git.kernel.org/stable/c/bc1c6b803e14ea2b8f7e33b7164013f666ceb656",
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
},
{
"url": "https://git.kernel.org/stable/c/d1894bc542becb0fda61e7e513b09523cab44030",
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
}
],
"vulnStatus": "Deferred",
"descriptions": [
{
"lang": "en",
"value": "In the Linux kernel, the following vulnerability has been resolved:\n\nfs/notify: call exportfs_encode_fid with s_umount\n\nCalling intotify_show_fdinfo() on fd watching an overlayfs inode, while\nthe overlayfs is being unmounted, can lead to dereferencing NULL ptr.\n\nThis issue was found by syzkaller.\n\nRace Condition Diagram:\n\nThread 1 Thread 2\n-------- --------\n\ngeneric_shutdown_super()\n shrink_dcache_for_umount\n sb->s_root = NULL\n\n |\n | vfs_read()\n | inotify_fdinfo()\n | * inode get from mark *\n | show_mark_fhandle(m, inode)\n | exportfs_encode_fid(inode, ..)\n | ovl_encode_fh(inode, ..)\n | ovl_check_encode_origin(inode)\n | * deref i_sb->s_root *\n |\n |\n v\n fsnotify_sb_delete(sb)\n\nWhich then leads to:\n\n[ 32.133461] Oops: general protection fault, probably for non-canonical address 0xdffffc0000000006: 0000 [#1] SMP DEBUG_PAGEALLOC KASAN NOPTI\n[ 32.134438] KASAN: null-ptr-deref in range [0x0000000000000030-0x0000000000000037]\n[ 32.135032] CPU: 1 UID: 0 PID: 4468 Comm: systemd-coredum Not tainted 6.17.0-rc6 #22 PREEMPT(none)\n\n<snip registers, unreliable trace>\n\n[ 32.143353] Call Trace:\n[ 32.143732] ovl_encode_fh+0xd5/0x170\n[ 32.144031] exportfs_encode_inode_fh+0x12f/0x300\n[ 32.144425] show_mark_fhandle+0xbe/0x1f0\n[ 32.145805] inotify_fdinfo+0x226/0x2d0\n[ 32.146442] inotify_show_fdinfo+0x1c5/0x350\n[ 32.147168] seq_show+0x530/0x6f0\n[ 32.147449] seq_read_iter+0x503/0x12a0\n[ 32.148419] seq_read+0x31f/0x410\n[ 32.150714] vfs_read+0x1f0/0x9e0\n[ 32.152297] ksys_read+0x125/0x240\n\nIOW ovl_check_encode_origin derefs inode->i_sb->s_root, after it was set\nto NULL in the unmount path.\n\nFix it by protecting calling exportfs_encode_fid() from\nshow_mark_fhandle() with s_umount lock.\n\nThis form of fix was suggested by Amir in [1].\n\n[1]: https://lore.kernel.org/all/CAOQ4uxhbDwhb+2Brs1UdkoF0a3NSdBAOQPNfEHjahrgoKJpLEw@mail.gmail.com/"
}
],
"lastModified": "2026-06-17T09:21:30.407",
"sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
}