CVE-2026-23107
In the Linux kernel, the following vulnerability has been resolved:
arm64/fpsimd: signal: Allocate SSVE storage when restoring ZA
The code to restore a ZA context doesn't attempt to allocate the task's sve_state before setting TIF_SME. Consequently, restoring a ZA context can place a task into an invalid state where TIF_SME is set but the task's sve_state is NULL.
In legitimate but uncommon cases where the ZA signal context was NOT created by the kernel in the context of the same task (e.g. if the task is saved/restored with something like CRIU), we have no guarantee that sve_state had been allocated previously.
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In these cases, userspace can enter streaming mode without trapping while sve_state is NULL, causing a later NULL pointer dereference when the kernel attempts to store the register state:
| # ./sigreturn-za | Unable to handle kernel NULL pointer dereference at virtual address 0000000000000000 | Mem abort info: | ESR = 0x0000000096000046 | EC = 0x25: DABT (current EL), IL = 32 bits | SET = 0, FnV = 0 | EA = 0, S1PTW = 0 | FSC = 0x06: level 2 translation fault | Data abort info: | ISV = 0, ISS = 0x00000046, ISS2 = 0x00000000 | CM = 0, WnR = 1, TnD = 0, TagAccess = 0 | GCS = 0, Overlay = 0, DirtyBit = 0, Xs = 0 | user pgtable: 4k pages, 52-bit VAs, pgdp=0000000101f47c00 | [0000000000000000] pgd=08000001021d8403, p4d=0800000102274403, pud=0800000102275403, pmd=0000000000000000 | Internal error: Oops: 0000000096000046 [#1] SMP | Modules linked in: | CPU: 0 UID: 0 PID: 153 Comm: sigreturn-za Not tainted 6.19.0-rc1 #1 PREEMPT | Hardware name: linux,dummy-virt (DT) | pstate: 214000c9 (nzCv daIF +PAN -UAO -TCO +DIT -SSBS BTYPE=--) | pc : sve_save_state+0x4/0xf0 | lr : fpsimd_save_user_state+0xb0/0x1c0 | sp : ffff80008070bcc0 | x29: ffff80008070bcc0 x28: fff00000c1ca4c40 x27: 63cfa172fb5cf658 | x26: fff00000c1ca5228 x25: 0000000000000000 x24: 0000000000000000 | x23: 0000000000000000 x22: fff00000c1ca4c40 x21: fff00000c1ca4c40 | x20: 0000000000000020 x19: fff00000ff6900f0 x18: 0000000000000000 | x17: fff05e8e0311f000 x16: 0000000000000000 x15: 028fca8f3bdaf21c | x14: 0000000000000212 x13: fff00000c0209f10 x12: 0000000000000020 | x11: 0000000000200b20 x10: 0000000000000000 x9 : fff00000ff69dcc0 | x8 : 00000000000003f2 x7 : 0000000000000001 x6 : fff00000c1ca5b48 | x5 : fff05e8e0311f000 x4 : 0000000008000000 x3 : 0000000000000000 | x2 : 0000000000000001 x1 : fff00000c1ca5970 x0 : 0000000000000440 | Call trace: | sve_save_state+0x4/0xf0 (P) | fpsimd_thread_switch+0x48/0x198 | __switch_to+0x20/0x1c0 | __schedule+0x36c/0xce0 | schedule+0x34/0x11c | exit_to_user_mode_loop+0x124/0x188 | el0_interrupt+0xc8/0xd8 | __el0_irq_handler_common+0x18/0x24 | el0t_64_irq_handler+0x10/0x1c | el0t_64_irq+0x198/0x19c | Code: 54000040 d51b4408 d65f03c0 d503245f (e5bb5800) | ---[ end trace 0000000000000000 ]---
Fix this by having restore_za_context() ensure that the task's sve_state is allocated, matching what we do when taking an SME trap. Any live SVE/SSVE state (which is restored earlier from a separate signal context) must be preserved, and hence this is not zeroed.
CVSS
- Versión: 3.1
- Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
- Puntuación base: 5.5
Probabilidad de explotación (EPSS)
- Probabilidad de explotación en los próximos 30 días: 0.15%
- Percentil entre todas las CVEs puntuadas: 3
- 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)
CWE
- CWE-476
Referencias
- https://git.kernel.org/stable/c/0af233d66eff90fb8f3e0fc09f2316bba0b72bb9
- https://git.kernel.org/stable/c/19b2c3f3ca1b4b6dccd2a42aca2692d8c79c4214
- https://git.kernel.org/stable/c/70f7f54566afc23f2c71bf1411af81f5d8009e0f
- https://git.kernel.org/stable/c/c5a5b150992ebab779c1ce54f54676786e47e94c
- https://git.kernel.org/stable/c/ea8ccfddbce0bee6310da4f3fc560ad520f5e6b4
JSON original (NVD)
Mostrar
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"value": "In the Linux kernel, the following vulnerability has been resolved:\n\narm64/fpsimd: signal: Allocate SSVE storage when restoring ZA\n\nThe code to restore a ZA context doesn't attempt to allocate the task's\nsve_state before setting TIF_SME. Consequently, restoring a ZA context\ncan place a task into an invalid state where TIF_SME is set but the\ntask's sve_state is NULL.\n\nIn legitimate but uncommon cases where the ZA signal context was NOT\ncreated by the kernel in the context of the same task (e.g. if the task\nis saved/restored with something like CRIU), we have no guarantee that\nsve_state had been allocated previously. In these cases, userspace can\nenter streaming mode without trapping while sve_state is NULL, causing a\nlater NULL pointer dereference when the kernel attempts to store the\nregister state:\n\n| # ./sigreturn-za\n| Unable to handle kernel NULL pointer dereference at virtual address 0000000000000000\n| Mem abort info:\n| ESR = 0x0000000096000046\n| EC = 0x25: DABT (current EL), IL = 32 bits\n| SET = 0, FnV = 0\n| EA = 0, S1PTW = 0\n| FSC = 0x06: level 2 translation fault\n| Data abort info:\n| ISV = 0, ISS = 0x00000046, ISS2 = 0x00000000\n| CM = 0, WnR = 1, TnD = 0, TagAccess = 0\n| GCS = 0, Overlay = 0, DirtyBit = 0, Xs = 0\n| user pgtable: 4k pages, 52-bit VAs, pgdp=0000000101f47c00\n| [0000000000000000] pgd=08000001021d8403, p4d=0800000102274403, pud=0800000102275403, pmd=0000000000000000\n| Internal error: Oops: 0000000096000046 [#1] SMP\n| Modules linked in:\n| CPU: 0 UID: 0 PID: 153 Comm: sigreturn-za Not tainted 6.19.0-rc1 #1 PREEMPT\n| Hardware name: linux,dummy-virt (DT)\n| pstate: 214000c9 (nzCv daIF +PAN -UAO -TCO +DIT -SSBS BTYPE=--)\n| pc : sve_save_state+0x4/0xf0\n| lr : fpsimd_save_user_state+0xb0/0x1c0\n| sp : ffff80008070bcc0\n| x29: ffff80008070bcc0 x28: fff00000c1ca4c40 x27: 63cfa172fb5cf658\n| x26: fff00000c1ca5228 x25: 0000000000000000 x24: 0000000000000000\n| x23: 0000000000000000 x22: fff00000c1ca4c40 x21: fff00000c1ca4c40\n| x20: 0000000000000020 x19: fff00000ff6900f0 x18: 0000000000000000\n| x17: fff05e8e0311f000 x16: 0000000000000000 x15: 028fca8f3bdaf21c\n| x14: 0000000000000212 x13: fff00000c0209f10 x12: 0000000000000020\n| x11: 0000000000200b20 x10: 0000000000000000 x9 : fff00000ff69dcc0\n| x8 : 00000000000003f2 x7 : 0000000000000001 x6 : fff00000c1ca5b48\n| x5 : fff05e8e0311f000 x4 : 0000000008000000 x3 : 0000000000000000\n| x2 : 0000000000000001 x1 : fff00000c1ca5970 x0 : 0000000000000440\n| Call trace:\n| sve_save_state+0x4/0xf0 (P)\n| fpsimd_thread_switch+0x48/0x198\n| __switch_to+0x20/0x1c0\n| __schedule+0x36c/0xce0\n| schedule+0x34/0x11c\n| exit_to_user_mode_loop+0x124/0x188\n| el0_interrupt+0xc8/0xd8\n| __el0_irq_handler_common+0x18/0x24\n| el0t_64_irq_handler+0x10/0x1c\n| el0t_64_irq+0x198/0x19c\n| Code: 54000040 d51b4408 d65f03c0 d503245f (e5bb5800)\n| ---[ end trace 0000000000000000 ]---\n\nFix this by having restore_za_context() ensure that the task's sve_state\nis allocated, matching what we do when taking an SME trap. Any live\nSVE/SSVE state (which is restored earlier from a separate signal\ncontext) must be preserved, and hence this is not zeroed."
},
{
"lang": "es",
"value": "En el kernel de Linux, la siguiente vulnerabilidad ha sido resuelta:\n\narm64/fpsimd: señal: Asignar almacenamiento SSVE al restaurar ZA\n\nEl código para restaurar un contexto ZA no intenta asignar el sve_state de la tarea antes de establecer TIF_SME. En consecuencia, restaurar un contexto ZA puede colocar una tarea en un estado inválido donde TIF_SME está establecido pero el sve_state de la tarea es NULL.\n\nEn casos legítimos pero poco comunes donde el contexto de señal ZA NO fue creado por el kernel en el contexto de la misma tarea (por ejemplo, si la tarea se guarda/restaura con algo como CRIU), no tenemos garantía de que sve_state se haya asignado previamente. En estos casos, el espacio de usuario puede entrar en modo de transmisión sin atrapar mientras sve_state es NULL, causando una desreferencia de puntero NULL posterior cuando el kernel intenta almacenar el estado del registro:\n\n| # ./sigreturn-za\n| Unable to handle kernel NULL pointer dereference at virtual address 0000000000000000\n| Mem abort info:\n| ESR = 0x0000000096000046\n| EC = 0x25: DABT (current EL), IL = 32 bits\n| SET = 0, FnV = 0\n| EA = 0, S1PTW = 0\n| FSC = 0x06: level 2 translation fault\n| Data abort info:\n| ISV = 0, ISS = 0x00000046, ISS2 = 0x00000000\n| CM = 0, WnR = 1, TnD = 0, TagAccess = 0\n| GCS = 0, Overlay = 0, DirtyBit = 0, Xs = 0\n| user pgtable: 4k pages, 52-bit VAs, pgdp=0000000101f47c00\n| [0000000000000000] pgd=08000001021d8403, p4d=0800000102274403, pud=0800000102275403, pmd=0000000000000000\n| Internal error: Oops: 0000000096000046 [#1] SMP\n| Modules linked in:\n| CPU: 0 UID: 0 PID: 153 Comm: sigreturn-za Not tainted 6.19.0-rc1 #1 PREEMPT\n| Hardware name: linux,dummy-virt (DT)\n| pstate: 214000c9 (nzCv daIF +PAN -UAO -TCO +DIT -SSBS BTYPE=--)\n| pc : sve_save_state+0x4/0xf0\n| lr : fpsimd_save_user_state+0xb0/0x1c0\n| sp : ffff80008070bcc0\n| x29: ffff80008070bcc0 x28: fff00000c1ca4c40 x27: 63cfa172fb5cf658\n| x26: fff00000c1ca5228 x25: 0000000000000000 x24: 0000000000000000\n| x23: 0000000000000000 x22: fff00000c1ca4c40 x21: fff00000c1ca4c40\n| x20: 0000000000000020 x19: fff00000ff6900f0 x18: 0000000000000000\n| x17: fff05e8e0311f000 x16: 0000000000000000 x15: 028fca8f3bdaf21c\n| x14: 0000000000000212 x13: fff00000c0209f10 x12: 0000000000000020\n| x11: 0000000000200b20 x10: 0000000000000000 x9 : fff00000ff69dcc0\n| x8 : 00000000000003f2 x7 : 0000000000000001 x6 : fff00000c1ca5b48\n| x5 : fff05e8e0311f000 x4 : 0000000008000000 x3 : 0000000000000000\n| x2 : 0000000000000001 x1 : fff00000c1ca5970 x0 : 0000000000000440\n| Call trace:\n| sve_save_state+0x4/0xf0 (P)\n| fpsimd_thread_switch+0x48/0x198\n| __switch_to+0x20/0x1c0\n| __schedule+0x36c/0xce0\n| schedule+0x34/0x11c\n| exit_to_user_mode_loop+0x124/0x188\n| el0_interrupt+0xc8/0xd8\n| __el0_irq_handler_common+0x18/0x24\n| el0t_64_irq_handler+0x10/0x1c\n| el0t_64_irq+0x198/0x19c\n| Code: 54000040 d51b4408 d65f03c0 d503245f (e5bb5800)\n| ---[ end trace 0000000000000000 ]---\n\nEsto se soluciona haciendo que restore_za_context() asegure que el sve_state de la tarea esté asignado, coincidiendo con lo que hacemos al tomar una trampa SME. Cualquier estado SVE/SSVE activo (que se restaura anteriormente desde un contexto de señal separado) debe ser preservado, y por lo tanto no se pone a cero."
}
],
"lastModified": "2026-06-17T10:20:54.343",
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