CVE-2021-47337
scsi: core: Fix bad pointer dereference when ehandler kthread is invalid
Severity Score
Exploit Likelihood
Affected Versions
Public Exploits
0Exploited in Wild
-Decision
Descriptions
In the Linux kernel, the following vulnerability has been resolved:
scsi: core: Fix bad pointer dereference when ehandler kthread is invalid
Commit 66a834d09293 ("scsi: core: Fix error handling of scsi_host_alloc()")
changed the allocation logic to call put_device() to perform host cleanup
with the assumption that IDA removal and stopping the kthread would
properly be performed in scsi_host_dev_release(). However, in the unlikely
case that the error handler thread fails to spawn, shost->ehandler is set
to ERR_PTR(-ENOMEM).
The error handler cleanup code in scsi_host_dev_release() will call
kthread_stop() if shost->ehandler != NULL which will always be the case
whether the kthread was successfully spawned or not. In the case that it
failed to spawn this has the nasty side effect of trying to dereference an
invalid pointer when kthread_stop() is called. The following splat provides
an example of this behavior in the wild:
scsi host11: error handler thread failed to spawn, error = -4
Kernel attempted to read user page (10c) - exploit attempt? (uid: 0)
BUG: Kernel NULL pointer dereference on read at 0x0000010c
Faulting instruction address: 0xc00000000818e9a8
Oops: Kernel access of bad area, sig: 11 [#1]
LE PAGE_SIZE=64K MMU=Hash SMP NR_CPUS=2048 NUMA pSeries
Modules linked in: ibmvscsi(+) scsi_transport_srp dm_multipath dm_mirror dm_region
hash dm_log dm_mod fuse overlay squashfs loop
CPU: 12 PID: 274 Comm: systemd-udevd Not tainted 5.13.0-rc7 #1
NIP: c00000000818e9a8 LR: c0000000089846e8 CTR: 0000000000007ee8
REGS: c000000037d12ea0 TRAP: 0300 Not tainted (5.13.0-rc7)
MSR: 800000000280b033 <SF,VEC,VSX,EE,FP,ME,IR,DR,RI,LE> CR: 28228228
XER: 20040001
CFAR: c0000000089846e4 DAR: 000000000000010c DSISR: 40000000 IRQMASK: 0
GPR00: c0000000089846e8 c000000037d13140 c000000009cc1100 fffffffffffffffc
GPR04: 0000000000000001 0000000000000000 0000000000000000 c000000037dc0000
GPR08: 0000000000000000 c000000037dc0000 0000000000000001 00000000fffff7ff
GPR12: 0000000000008000 c00000000a049000 c000000037d13d00 000000011134d5a0
GPR16: 0000000000001740 c0080000190d0000 c0080000190d1740 c000000009129288
GPR20: c000000037d13bc0 0000000000000001 c000000037d13bc0 c0080000190b7898
GPR24: c0080000190b7708 0000000000000000 c000000033bb2c48 0000000000000000
GPR28: c000000046b28280 0000000000000000 000000000000010c fffffffffffffffc
NIP [c00000000818e9a8] kthread_stop+0x38/0x230
LR [c0000000089846e8] scsi_host_dev_release+0x98/0x160
Call Trace:
[c000000033bb2c48] 0xc000000033bb2c48 (unreliable)
[c0000000089846e8] scsi_host_dev_release+0x98/0x160
[c00000000891e960] device_release+0x60/0x100
[c0000000087e55c4] kobject_release+0x84/0x210
[c00000000891ec78] put_device+0x28/0x40
[c000000008984ea4] scsi_host_alloc+0x314/0x430
[c0080000190b38bc] ibmvscsi_probe+0x54/0xad0 [ibmvscsi]
[c000000008110104] vio_bus_probe+0xa4/0x4b0
[c00000000892a860] really_probe+0x140/0x680
[c00000000892aefc] driver_probe_device+0x15c/0x200
[c00000000892b63c] device_driver_attach+0xcc/0xe0
[c00000000892b740] __driver_attach+0xf0/0x200
[c000000008926f28] bus_for_each_dev+0xa8/0x130
[c000000008929ce4] driver_attach+0x34/0x50
[c000000008928fc0] bus_add_driver+0x1b0/0x300
[c00000000892c798] driver_register+0x98/0x1a0
[c00000000810eb60] __vio_register_driver+0x80/0xe0
[c0080000190b4a30] ibmvscsi_module_init+0x9c/0xdc [ibmvscsi]
[c0000000080121d0] do_one_initcall+0x60/0x2d0
[c000000008261abc] do_init_module+0x7c/0x320
[c000000008265700] load_module+0x2350/0x25b0
[c000000008265cb4] __do_sys_finit_module+0xd4/0x160
[c000000008031110] system_call_exception+0x150/0x2d0
[c00000000800d35c] system_call_common+0xec/0x278
Fix this be nulling shost->ehandler when the kthread fails to spawn.
En el kernel de Linux, se resolvió la siguiente vulnerabilidad: scsi: core: corrige la desreferencia del puntero incorrecto cuando ehandler kthread no es válido. La confirmación 66a834d09293 ("scsi: core: corrige el manejo de errores de scsi_host_alloc()") cambió la lógica de asignación para llamar a put_device( ) para realizar la limpieza del host asumiendo que la eliminación de IDA y la detención del kthread se realizarían correctamente en scsi_host_dev_release(). Sin embargo, en el improbable caso de que el subproceso del controlador de errores no se genere, shost->ehandler se establece en ERR_PTR(-ENOMEM). El código de limpieza del controlador de errores en scsi_host_dev_release() llamará a kthread_stop() si shost->ehandler != NULL, que siempre será el caso ya sea que kthread se genere exitosamente o no. En el caso de que no se genere, esto tiene el desagradable efecto secundario de intentar eliminar la referencia a un puntero no válido cuando se llama a kthread_stop(). El siguiente símbolo proporciona un ejemplo de este comportamiento en la naturaleza: scsi host11: el hilo del controlador de errores no pudo generarse, error = -4 El kernel intentó leer la página del usuario (10c): ¿intento de explotación? (uid: 0) ERROR: Desreferencia del puntero NULL del kernel al leer en 0x0000010c Dirección de instrucción errónea: 0xc00000000818e9a8 Ups: Acceso al kernel del área defectuosa, firma: 11 [#1] LE PAGE_SIZE=64K MMU=Hash SMP NR_CPUS=2048 Módulos NUMA pSeries vinculados en: ibmvscsi(+) scsi_transport_srp dm_multipath dm_mirror dm_region hash dm_log dm_mod fuse overlay squashfs loop CPU: 12 PID: 274 Comm: systemd-udevd Not tainted 5.13.0-rc7 #1 NIP: c00000000818e9a8 LR: 9846e8 CTR: 0000000000007ee8 REGS: c000000037d12ea0 TRAMPA : 0300 No contaminado (5.13.0-rc7) MSR: 800000000280b033 <SF,VEC,VSX,EE,FP,ME,IR,DR,RI,LE> CR: 28228228 XER: 20040001 CFAR: c0000000089846e4 DAR: 000000000000010c DSISR: 40000000 IRQMASK: 0 GPR00: c0000000089846e8 c000000037d13140 000009cc1100 ffffffffffffffffc GPR04: 0000000000000001 0000000000000000 0000000000000000 c000000037dc0000 GPR08: 0000000000000000 c000000037 dc0000 0000000000000001 00000000fffff7ff GPR12: 0000000000008000 c00000000a049000 c000000037d13d00 000000011134d5a0 GPR16: 001740 c0080000190d0000 c0080000190d1740 c000000009129288 GPR20: c000000037d13bc0 0000000000000001 c000000037d13bc0 c0080000190b7898 GPR24: c0080000190b7708 0000000000000000 c000000033bb2c48 000000 0000000000 GPR28: c000000046b28280 0000000000000000 000000000000010c ffffffffffffffffc NIP [c00000000818e9a8] kthread_stop+0x38/0x230 LR [c0000000089 846e8] scsi_host_dev_release+0x98/0x160 Seguimiento de llamadas: [c000000033bb2c48] 0xc000000033bb2c48 (no confiable) [c0000000089846e8] scsi_host_dev_release+0x98 /0x160 [c00000000891e960] device_release+0x60/0x100 [c0000000087e55c4] kobject_release+0x84/0x210 [c00000000891ec78] put_device+0x28/0x40 [c000000008984ea4] host_alloc+0x314/0x430 [c0080000190b38bc] ibmvscsi_probe+0x54/0xad0 [ibmvscsi] [c000000008110104] vio_bus_probe+ 0xa4/0x4b0 [c00000000892a860] very_probe+0x140/0x680 [c00000000892aefc] driver_probe_device+0x15c/0x200 [c00000000892b63c] device_driver_attach+0xcc/0xe0 [c0000000 0892b740] __driver_attach+0xf0/0x200 [c000000008926f28] bus_for_each_dev+0xa8/0x130 [c000000008929ce4] driver_attach+0x34/ 0x50 [c000000008928fc0] bus_add_driver+0x1b0/0x300 [c00000000892c798] driver_register+0x98/0x1a0 [c00000000810eb60] __vio_register_driver+0x80/0xe0 [c0080000190 b4a30] ibmvscsi_module_init+0x9c/0xdc [ibmvscsi] [c0000000080121d0] do_one_initcall+0x60/0x2d0 [c000000008261abc] do_init_module+0x7c /0x320 [c000000008265700] load_module+0x2350/0x25b0 [c000000008265cb4] __do_sys_finit_module+0xd4/0x160 [c000000008031110] system_call_exception+0x150/0x2d0 [c00 000000800d35c] system_call_common+0xec/0x278 Se soluciona esto al anular shost->ehandler cuando el kthread no se genera.
CVSS Scores
SSVC
- Decision:Track
Timeline
- 2024-05-21 CVE Reserved
- 2024-05-21 CVE Published
- 2024-05-22 EPSS Updated
- 2024-12-19 CVE Updated
- ---------- Exploited in Wild
- ---------- KEV Due Date
- ---------- First Exploit
CWE
CAPEC
References (15)
URL | Tag | Source |
---|---|---|
https://git.kernel.org/stable/c/8958181c1663e24a13434448e7d6b96b5d04900a | Vuln. Introduced | |
https://git.kernel.org/stable/c/db08ce595dd64ea9859f7d088b51cbfc8e685c66 | Vuln. Introduced | |
https://git.kernel.org/stable/c/2dc85045ae65b9302a1d2e2ddd7ce4c030153a6a | Vuln. Introduced | |
https://git.kernel.org/stable/c/79296e292d67fa7b5fb8d8c27343683e823872c8 | Vuln. Introduced | |
https://git.kernel.org/stable/c/7a696ce1d5d16a33a6cd6400bbcc0339b2460e11 | Vuln. Introduced | |
https://git.kernel.org/stable/c/45d83db4728127944b237c0c8248987df9d478e7 | Vuln. Introduced | |
https://git.kernel.org/stable/c/66a834d092930cf41d809c0e989b13cd6f9ca006 | Vuln. Introduced |
URL | Date | SRC |
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URL | Date | SRC |
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Affected Vendors, Products, and Versions
Vendor | Product | Version | Other | Status | ||||||
---|---|---|---|---|---|---|---|---|---|---|
Vendor | Product | Version | Other | Status | <-- --> | Vendor | Product | Version | Other | Status |
Linux Search vendor "Linux" | Linux Kernel Search vendor "Linux" for product "Linux Kernel" | >= 4.9.273 < 4.9.276 Search vendor "Linux" for product "Linux Kernel" and version " >= 4.9.273 < 4.9.276" | en |
Affected
| ||||||
Linux Search vendor "Linux" | Linux Kernel Search vendor "Linux" for product "Linux Kernel" | >= 4.14.237 < 4.14.240 Search vendor "Linux" for product "Linux Kernel" and version " >= 4.14.237 < 4.14.240" | en |
Affected
| ||||||
Linux Search vendor "Linux" | Linux Kernel Search vendor "Linux" for product "Linux Kernel" | >= 4.19.195 < 4.19.198 Search vendor "Linux" for product "Linux Kernel" and version " >= 4.19.195 < 4.19.198" | en |
Affected
| ||||||
Linux Search vendor "Linux" | Linux Kernel Search vendor "Linux" for product "Linux Kernel" | >= 5.4.126 < 5.4.134 Search vendor "Linux" for product "Linux Kernel" and version " >= 5.4.126 < 5.4.134" | en |
Affected
| ||||||
Linux Search vendor "Linux" | Linux Kernel Search vendor "Linux" for product "Linux Kernel" | >= 5.10.44 < 5.10.52 Search vendor "Linux" for product "Linux Kernel" and version " >= 5.10.44 < 5.10.52" | en |
Affected
| ||||||
Linux Search vendor "Linux" | Linux Kernel Search vendor "Linux" for product "Linux Kernel" | >= 5.12.11 < 5.12.19 Search vendor "Linux" for product "Linux Kernel" and version " >= 5.12.11 < 5.12.19" | en |
Affected
| ||||||
Linux Search vendor "Linux" | Linux Kernel Search vendor "Linux" for product "Linux Kernel" | >= 5.13 < 5.13.4 Search vendor "Linux" for product "Linux Kernel" and version " >= 5.13 < 5.13.4" | en |
Affected
| ||||||
Linux Search vendor "Linux" | Linux Kernel Search vendor "Linux" for product "Linux Kernel" | >= 5.13 < 5.14 Search vendor "Linux" for product "Linux Kernel" and version " >= 5.13 < 5.14" | en |
Affected
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