CVE-2024-49885
Status: AnalyzedMedium (5.5)—
In the Linux kernel, the following vulnerability has been resolved:
mm, slub: avoid zeroing kmalloc redzone
Since commit 946fa0dbf2d8 ("mm/slub: extend redzone check to extra allocated kmalloc space than requested"), setting orig_size treats the wasted space (object_size - orig_size) as a redzone. However with init_on_free=1 we clear the full object->size, including the redzone.
Additionally we clear the object metadata, including the stored orig_size, making it zero, which makes check_object() treat the whole object as a redzone.
These issues lead to the following BUG report with "slub_debug=FUZ init_on_free=1":
Read full descriptionShow less
To address the issue, use orig_size to clear the used area. And restore the value of orig_size after clear the remaining area.
When CONFIG_SLUB_DEBUG not defined, (get_orig_size()' directly returns s->object_size. So when using memset to init the area, the size can simply be orig_size, as orig_size returns object_size when CONFIG_SLUB_DEBUG not enabled. And orig_size can never be bigger than object_size.
Technical details traces, logs and code from the original report
[ 0.000000] ============================================================================= [ 0.000000] BUG kmalloc-8 (Not tainted): kmalloc Redzone overwritten [ 0.000000] ----------------------------------------------------------------------------- [ 0.000000] [ 0.000000] 0xffff000010032858-0xffff00001003285f @offset=2136. First byte 0x0 instead of 0xcc [ 0.000000] FIX kmalloc-8: Restoring kmalloc Redzone 0xffff000010032858-0xffff00001003285f=0xcc [ 0.000000] Slab 0xfffffdffc0400c80 objects=36 used=23 fp=0xffff000010032a18 flags=0x3fffe0000000200(workingset|node=0|zone=0|lastcpupid=0x1ffff) [ 0.000000] Object 0xffff000010032858 @offset=2136 fp=0xffff0000100328c8 [ 0.000000] [ 0.000000] Redzone ffff000010032850: cc cc cc cc cc cc cc cc ........ [ 0.000000] Object ffff000010032858: cc cc cc cc cc cc cc cc ........ [ 0.000000] Redzone ffff000010032860: cc cc cc cc cc cc cc cc ........ [ 0.000000] Padding ffff0000100328b4: 00 00 00 00 00 00 00 00 00 00 00 00 ............ [ 0.000000] CPU: 0 UID: 0 PID: 0 Comm: swapper/0 Not tainted 6.11.0-rc3-next-20240814-00004-g61844c55c3f4 #144 [ 0.000000] Hardware name: NXP i.MX95 19X19 board (DT) [ 0.000000] Call trace: [ 0.000000] dump_backtrace+0x90/0xe8 [ 0.000000] show_stack+0x18/0x24 [ 0.000000] dump_stack_lvl+0x74/0x8c [ 0.000000] dump_stack+0x18/0x24 [ 0.000000] print_trailer+0x150/0x218 [ 0.000000] check_object+0xe4/0x454 [ 0.000000] free_to_partial_list+0x2f8/0x5ec
CVSS
- Version: 3.1
- Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
- Base score: 5.5
Exploitation probability (EPSS)
- Probability of exploitation in the next 30 days: 0.24%
- Percentile among all scored CVEs: 13
- Score date: 10/6/2026
EPSS (Exploit Prediction Scoring System, FIRST) estimates how likely a vulnerability is to be exploited in the wild within 30 days. It complements CVSS (impact) and CISA KEV (confirmed exploitation).
Affected technologies (1)
CWEs
- NVD-CWE-noinfo
References
Raw JSON (NVD)
Show
{
"id": "CVE-2024-49885",
"cveTags": [],
"metrics": {
"ssvcV203": [
{
"source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
"ssvcData": {
"id": "CVE-2024-49885",
"role": "CISA Coordinator",
"options": [
{
"exploitation": "none"
},
{
"automatable": "no"
},
{
"technicalImpact": "partial"
}
],
"version": "2.0.3",
"timestamp": "2024-10-22T13:45:07.682094Z"
}
}
],
"cvssMetricV31": [
{
"type": "Primary",
"source": "nvd@nist.gov",
"cvssData": {
"scope": "UNCHANGED",
"version": "3.1",
"baseScore": 5.5,
"attackVector": "LOCAL",
"baseSeverity": "MEDIUM",
"vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H",
"integrityImpact": "NONE",
"userInteraction": "NONE",
"attackComplexity": "LOW",
"availabilityImpact": "HIGH",
"privilegesRequired": "LOW",
"confidentialityImpact": "NONE"
},
"impactScore": 3.6,
"exploitabilityScore": 1.8
}
]
},
"affected": [
{
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"affectedData": [
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"vendor": "Linux",
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"versions": [
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"programFiles": [
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{
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"vendor": "Linux",
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{
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"version": "0",
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{
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{
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"version": "6.11.3",
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{
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"version": "6.12",
"versionType": "original_commit_for_fix",
"lessThanOrEqual": "*"
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"published": "2024-10-21T18:15:11.230",
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{
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"tags": [
"Patch"
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"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
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"vulnStatus": "Analyzed",
"weaknesses": [
{
"type": "Primary",
"source": "nvd@nist.gov",
"description": [
{
"lang": "en",
"value": "NVD-CWE-noinfo"
}
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"descriptions": [
{
"lang": "en",
"value": "In the Linux kernel, the following vulnerability has been resolved:\n\nmm, slub: avoid zeroing kmalloc redzone\n\nSince commit 946fa0dbf2d8 (\"mm/slub: extend redzone check to extra\nallocated kmalloc space than requested\"), setting orig_size treats\nthe wasted space (object_size - orig_size) as a redzone. However with\ninit_on_free=1 we clear the full object->size, including the redzone.\n\nAdditionally we clear the object metadata, including the stored orig_size,\nmaking it zero, which makes check_object() treat the whole object as a\nredzone.\n\nThese issues lead to the following BUG report with \"slub_debug=FUZ\ninit_on_free=1\":\n\n[ 0.000000] =============================================================================\n[ 0.000000] BUG kmalloc-8 (Not tainted): kmalloc Redzone overwritten\n[ 0.000000] -----------------------------------------------------------------------------\n[ 0.000000]\n[ 0.000000] 0xffff000010032858-0xffff00001003285f @offset=2136. First byte 0x0 instead of 0xcc\n[ 0.000000] FIX kmalloc-8: Restoring kmalloc Redzone 0xffff000010032858-0xffff00001003285f=0xcc\n[ 0.000000] Slab 0xfffffdffc0400c80 objects=36 used=23 fp=0xffff000010032a18 flags=0x3fffe0000000200(workingset|node=0|zone=0|lastcpupid=0x1ffff)\n[ 0.000000] Object 0xffff000010032858 @offset=2136 fp=0xffff0000100328c8\n[ 0.000000]\n[ 0.000000] Redzone ffff000010032850: cc cc cc cc cc cc cc cc ........\n[ 0.000000] Object ffff000010032858: cc cc cc cc cc cc cc cc ........\n[ 0.000000] Redzone ffff000010032860: cc cc cc cc cc cc cc cc ........\n[ 0.000000] Padding ffff0000100328b4: 00 00 00 00 00 00 00 00 00 00 00 00 ............\n[ 0.000000] CPU: 0 UID: 0 PID: 0 Comm: swapper/0 Not tainted 6.11.0-rc3-next-20240814-00004-g61844c55c3f4 #144\n[ 0.000000] Hardware name: NXP i.MX95 19X19 board (DT)\n[ 0.000000] Call trace:\n[ 0.000000] dump_backtrace+0x90/0xe8\n[ 0.000000] show_stack+0x18/0x24\n[ 0.000000] dump_stack_lvl+0x74/0x8c\n[ 0.000000] dump_stack+0x18/0x24\n[ 0.000000] print_trailer+0x150/0x218\n[ 0.000000] check_object+0xe4/0x454\n[ 0.000000] free_to_partial_list+0x2f8/0x5ec\n\nTo address the issue, use orig_size to clear the used area. And restore\nthe value of orig_size after clear the remaining area.\n\nWhen CONFIG_SLUB_DEBUG not defined, (get_orig_size()' directly returns\ns->object_size. So when using memset to init the area, the size can simply\nbe orig_size, as orig_size returns object_size when CONFIG_SLUB_DEBUG not\nenabled. And orig_size can never be bigger than object_size."
},
{
"lang": "es",
"value": "En el kernel de Linux, se ha resuelto la siguiente vulnerabilidad: mm, slub: evitar poner a cero la zona roja de kmalloc Desde el commit 946fa0dbf2d8 (\"mm/slub: extender la comprobación de la zona roja a espacio de kmalloc asignado adicional al solicitado\"), al establecer orig_size se trata el espacio desperdiciado (object_size - orig_size) como una zona roja. Sin embargo, con init_on_free=1 borramos todo el objeto->size, incluida la zona roja. Además, borramos los metadatos del objeto, incluido el orig_size almacenado, haciéndolo cero, lo que hace que check_object() trate todo el objeto como una zona roja. Estos problemas conducen al siguiente informe de ERROR con \"slub_debug=FUZ init_on_free=1\": [ 0.000000] ===================================================================================== [ 0.000000] ERROR kmalloc-8 (no contaminado): kmalloc Redzone sobrescrito [ 0.000000] ----------------------------------------------------------------------------- [ 0.000000] [ 0.000000] 0xffff000010032858-0xffff00001003285f @offset=2136. Primer byte 0x0 en lugar de 0xcc [ 0.000000] CORREGIR kmalloc-8: Restaurando kmalloc Redzone 0xffff000010032858-0xffff00001003285f=0xcc [ 0.000000] Losa 0xfffffdffc0400c80 objetos=36 usados=23 fp=0xffff000010032a18 indicadores=0x3fffe0000000200(workingset|node=0|zone=0|lastcpupid=0x1ffff) [ 0.000000] Objeto 0xffff000010032858 @offset=2136 fp=0xffff0000100328c8 [ 0.000000] [ 0.000000] Redzone ffff000010032850: cc cc cc cc cc cc cc cc ........ [ 0.000000] Objeto ffff000010032858: cc cc cc cc cc cc cc cc cc ........ [ 0.000000] Redzone ffff000010032860: cc cc cc cc cc cc cc cc cc ........ [ 0.000000] Relleno ffff0000100328b4: 00 00 00 00 00 00 00 00 00 00 00 00 ............ [ 0.000000] CPU: 0 UID: 0 PID: 0 Comm: intercambiador/0 No contaminado 6.11.0-rc3-next-20240814-00004-g61844c55c3f4 #144 [ 0.000000] Nombre del hardware: Placa NXP i.MX95 19X19 (DT) [ 0.000000] Rastreo de llamadas: [ 0.000000] dump_backtrace+0x90/0xe8 [ 0.000000] show_stack+0x18/0x24 [ 0.000000] dump_stack_lvl+0x74/0x8c [ 0.000000] dump_stack+0x18/0x24 [ 0.000000] print_trailer+0x150/0x218 [ 0.000000] check_object+0xe4/0x454 [ 0.000000] free_to_partial_list+0x2f8/0x5ec Para solucionar el problema, use orig_size para limpiar el área usada. Y restaure el valor de orig_size después de limpiar el área restante. Cuando CONFIG_SLUB_DEBUG no está definido, (get_orig_size()' retorna directamente s->object_size. Entonces, cuando se usa memset para inicializar el área, el tamaño puede ser simplemente orig_size, ya que orig_size retorna object_size cuando CONFIG_SLUB_DEBUG no está habilitado. Y orig_size nunca puede ser mayor que object_size."
}
],
"lastModified": "2026-06-17T08:00:39.643",
"configurations": [
{
"nodes": [
{
"negate": false,
"cpeMatch": [
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"sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
}