CVE-2025-39904
Full vulnerability record from the local CVENow database.
Description
In the Linux kernel, the following vulnerability has been resolved: arm64: kexec: initialize kexec_buf struct in load_other_segments() Patch series "kexec: Fix invalid field access". The kexec_buf structure was previously declared without initialization. commit bf454ec31add ("kexec_file: allow to place kexec_buf randomly") added a field that is always read but not consistently populated by all architectures. This un-initialized field will contain garbage. This is also triggering a UBSAN warning when the uninitialized data was accessed: ------------[ cut here ]------------ UBSAN: invalid-load in ./include/linux/kexec.h:210:10 load of value 252 is not a valid value for type '_Bool' Zero-initializing kexec_buf at declaration ensures all fields are cleanly set, preventing future instances of uninitialized memory being used. An initial fix was already landed for arm64[0], and this patchset fixes the problem on the remaining arm64 code and on riscv, as raised by Mark. Discussions about this problem could be found at[1][2]. This patch (of 3): The kexec_buf structure was previously declared without initialization. commit bf454ec31add ("kexec_file: allow to place kexec_buf randomly") added a field that is always read but not consistently populated by all architectures. This un-initialized field will contain garbage. This is also triggering a UBSAN warning when the uninitialized data was accessed: ------------[ cut here ]------------ UBSAN: invalid-load in ./include/linux/kexec.h:210:10 load of value 252 is not a valid value for type '_Bool' Zero-initializing kexec_buf at declaration ensures all fields are cleanly set, preventing future instances of uninitialized memory being used.
Severity
MEDIUM
CVSS score
5.5
(v3.1)
Vulnerability status
Modified
Source identifier
416baaa9-dc9f-4396-8d5f-8c081fb06d67
Published
2025-10-01 08:15:33.250000
Last modified
2026-10-19 21:10:00.160000
View original CVE JSON
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"sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"published": "2025-10-01T08:15:33.250",
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"value": "In the Linux kernel, the following vulnerability has been resolved:\n\narm64: kexec: initialize kexec_buf struct in load_other_segments()\n\nPatch series \"kexec: Fix invalid field access\".\n\nThe kexec_buf structure was previously declared without initialization. \ncommit bf454ec31add (\"kexec_file: allow to place kexec_buf randomly\")\nadded a field that is always read but not consistently populated by all\narchitectures. This un-initialized field will contain garbage.\n\nThis is also triggering a UBSAN warning when the uninitialized data was\naccessed:\n\n\t------------[ cut here ]------------\n\tUBSAN: invalid-load in ./include/linux/kexec.h:210:10\n\tload of value 252 is not a valid value for type '_Bool'\n\nZero-initializing kexec_buf at declaration ensures all fields are cleanly\nset, preventing future instances of uninitialized memory being used.\n\nAn initial fix was already landed for arm64[0], and this patchset fixes\nthe problem on the remaining arm64 code and on riscv, as raised by Mark.\n\nDiscussions about this problem could be found at[1][2].\n\n\nThis patch (of 3):\n\nThe kexec_buf structure was previously declared without initialization.\ncommit bf454ec31add (\"kexec_file: allow to place kexec_buf randomly\")\nadded a field that is always read but not consistently populated by all\narchitectures. This un-initialized field will contain garbage.\n\nThis is also triggering a UBSAN warning when the uninitialized data was\naccessed:\n\n\t------------[ cut here ]------------\n\tUBSAN: invalid-load in ./include/linux/kexec.h:210:10\n\tload of value 252 is not a valid value for type '_Bool'\n\nZero-initializing kexec_buf at declaration ensures all fields are\ncleanly set, preventing future instances of uninitialized memory being\nused."
},
{
"lang": "es",
"value": "En el kernel de Linux, la siguiente vulnerabilidad ha sido resuelta:\n\narm64: kexec: inicializar la estructura kexec_buf en load_other_segments()\n\nSerie de parches 'kexec: Corrección de acceso a campo inválido'.\n\nLa estructura kexec_buf fue declarada previamente sin inicialización.\nEl commit bf454ec31add ('kexec_file: permitir colocar kexec_buf aleatoriamente')\nañadió un campo que siempre se lee pero no es poblado consistentemente por todas\nlas arquitecturas. Este campo no inicializado contendrá basura.\n\nEsto también está activando una advertencia de UBSAN cuando se accedió a los datos no inicializados:\n\n\t------------[ cortar aquí ]------------\n\tUBSAN: carga inválida en ./include/linux/kexec.h:210:10\n\tcarga del valor 252 no es un valor válido para el tipo '_Bool'\n\nInicializar kexec_buf a cero en la declaración asegura que todos los campos se establezcan limpiamente,\npreviniendo futuras instancias de memoria no inicializada siendo utilizada.\n\nUna corrección inicial ya fue aplicada para arm64[0], y este conjunto de parches corrige\nel problema en el código arm64 restante y en riscv, como lo planteó Mark.\n\nLas discusiones sobre este problema se pueden encontrar en[1][2].\n\nEste parche (de 3):\n\nLa estructura kexec_buf fue declarada previamente sin inicialización.\nEl commit bf454ec31add ('kexec_file: permitir colocar kexec_buf aleatoriamente')\nañadió un campo que siempre se lee pero no es poblado consistentemente por todas\nlas arquitecturas. Este campo no inicializado contendrá basura.\n\nEsto también está activando una advertencia de UBSAN cuando se accedió a los datos no inicializados:\n\n\t------------[ cortar aquí ]------------\n\tUBSAN: carga inválida en ./include/linux/kexec.h:210:10\n\tcarga del valor 252 no es un valor válido para el tipo '_Bool'\n\nInicializar kexec_buf a cero en la declaración asegura que todos los campos se\nestablezcan limpiamente, previniendo futuras instancias de memoria no\ninicializada siendo utilizada."
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