CVE-2022-49006

In the Linux kernel, the following vulnerability has been resolved: tracing: Free buffers when a used dynamic event is removed After 65536 dynamic events have been added and removed, the "type" field of the event then uses the first type number that is available (not currently used by other events). A type number is the identifier of the binary blobs in the tracing ring buffer (known as events) to map them to logic that can parse the binary blob. The issue is that if a dynamic event (like a kprobe event) is traced and is in the ring buffer, and then that event is removed (because it is dynamic, which means it can be created and destroyed), if another dynamic event is created that has the same number that new event's logic on parsing the binary blob will be used. To show how this can be an issue, the following can crash the kernel: # cd /sys/kernel/tracing # for i in `seq 65536`; do echo 'p:kprobes/foo do_sys_openat2 $arg1:u32' > kprobe_events # done For every iteration of the above, the writing to the kprobe_events will remove the old event and create a new one (with the same format) and increase the type number to the next available on until the type number reaches over 65535 which is the max number for the 16 bit type. After it reaches that number, the logic to allocate a new number simply looks for the next available number. When an dynamic event is removed, that number is then available to be reused by the next dynamic event created. That is, once the above reaches the max number, the number assigned to the event in that loop will remain the same. Now that means deleting one dynamic event and created another will reuse the previous events type number. This is where bad things can happen. After the above loop finishes, the kprobes/foo event which reads the do_sys_openat2 function call's first parameter as an integer. # echo 1 > kprobes/foo/enable # cat /etc/passwd > /dev/null # cat trace cat-2211 [005] .... 2007.849603: foo: (do_sys_openat2+0x0/0x130) arg1=4294967196 cat-2211 [005] .... 2007.849620: foo: (do_sys_openat2+0x0/0x130) arg1=4294967196 cat-2211 [005] .... 2007.849838: foo: (do_sys_openat2+0x0/0x130) arg1=4294967196 cat-2211 [005] .... 2007.849880: foo: (do_sys_openat2+0x0/0x130) arg1=4294967196 # echo 0 > kprobes/foo/enable Now if we delete the kprobe and create a new one that reads a string: # echo 'p:kprobes/foo do_sys_openat2 +0($arg2):string' > kprobe_events And now we can the trace: # cat trace sendmail-1942 [002] ..... 530.136320: foo: (do_sys_openat2+0x0/0x240) arg1= cat-2046 [004] ..... 530.930817: foo: (do_sys_openat2+0x0/0x240) arg1="��" cat-2046 [004] ..... 530.930961: foo: (do_sys_openat2+0x0/0x240) arg1="��" cat-2046 [004] ..... 530.934278: foo: (do_sys_openat2+0x0/0x240) arg1="��" cat-2046 [004] ..... 530.934563: foo: (do_sys_openat2+0x0/0x240) arg1="�� ---truncated---

References

Link	Resource
https://git.kernel.org/stable/c/1603feac154ff38514e8354e3079a455eb4801e2	Patch
https://git.kernel.org/stable/c/417d5ea6e735e5d88ffb6c436cf2938f3f476dd1	Patch
https://git.kernel.org/stable/c/4313e5a613049dfc1819a6dfb5f94cf2caff9452	Patch
https://git.kernel.org/stable/c/be111ebd8868d4b7c041cb3c6102e1ae27d6dc1d	Patch
https://git.kernel.org/stable/c/c52d0c8c4f38f7580cff61c4dfe1034c580cedfd	Patch

Configurations

Configuration 1 (hide)

OR	cpe:2.3:o:linux:linux_kernel::::::::
	cpe:2.3:o:linux:linux_kernel::::::::
	cpe:2.3:o:linux:linux_kernel::::::::
	cpe:2.3:o:linux:linux_kernel::::::::
	cpe:2.3:o:linux:linux_kernel:6.1:rc1::::::
	cpe:2.3:o:linux:linux_kernel:6.1:rc2::::::
	cpe:2.3:o:linux:linux_kernel:6.1:rc3::::::
	cpe:2.3:o:linux:linux_kernel:6.1:rc4::::::
	cpe:2.3:o:linux:linux_kernel:6.1:rc5::::::
	cpe:2.3:o:linux:linux_kernel:6.1:rc6::::::
	cpe:2.3:o:linux:linux_kernel:6.1:rc7::::::

History

04 Nov 2024, 13:16

Type	Values Removed	Values Added
Summary	(en) In the Linux kernel, the following vulnerability has been resolved: tracing: Free buffers when a used dynamic event is removed After 65536 dynamic events have been added and removed, the "type" field of the event then uses the first type number that is available (not currently used by other events). A type number is the identifier of the binary blobs in the tracing ring buffer (known as events) to map them to logic that can parse the binary blob. The issue is that if a dynamic event (like a kprobe event) is traced and is in the ring buffer, and then that event is removed (because it is dynamic, which means it can be created and destroyed), if another dynamic event is created that has the same number that new event's logic on parsing the binary blob will be used. To show how this can be an issue, the following can crash the kernel: # cd /sys/kernel/tracing # for i in `seq 65536`; do echo 'p:kprobes/foo do_sys_openat2 $arg1:u32' > kprobe_events # done For every iteration of the above, the writing to the kprobe_events will remove the old event and create a new one (with the same format) and increase the type number to the next available on until the type number reaches over 65535 which is the max number for the 16 bit type. After it reaches that number, the logic to allocate a new number simply looks for the next available number. When an dynamic event is removed, that number is then available to be reused by the next dynamic event created. That is, once the above reaches the max number, the number assigned to the event in that loop will remain the same. Now that means deleting one dynamic event and created another will reuse the previous events type number. This is where bad things can happen. After the above loop finishes, the kprobes/foo event which reads the do_sys_openat2 function call's first parameter as an integer. # echo 1 > kprobes/foo/enable # cat /etc/passwd > /dev/null # cat trace cat-2211 [005] .... 2007.849603: foo: (do_sys_openat2+0x0/0x130) arg1=4294967196 cat-2211 [005] .... 2007.849620: foo: (do_sys_openat2+0x0/0x130) arg1=4294967196 cat-2211 [005] .... 2007.849838: foo: (do_sys_openat2+0x0/0x130) arg1=4294967196 cat-2211 [005] .... 2007.849880: foo: (do_sys_openat2+0x0/0x130) arg1=4294967196 # echo 0 > kprobes/foo/enable Now if we delete the kprobe and create a new one that reads a string: # echo 'p:kprobes/foo do_sys_openat2 +0($arg2):string' > kprobe_events And now we can the trace: # cat trace sendmail-1942 [002] ..... 530.136320: foo: (do_sys_openat2+0x0/0x240) arg1= cat-2046 [004] ..... 530.930817: foo: (do_sys_openat2+0x0/0x240) arg1="????????????????????????????????????????????????????????????????????????????????????????????????" cat-2046 [004] ..... 530.930961: foo: (do_sys_openat2+0x0/0x240) arg1="????????????????????????????????????????????????????????????????????????????????????????????????" cat-2046 [004] ..... 530.934278: foo: (do_sys_openat2+0x0/0x240) arg1="????????????????????????????????????????????????????????????????????????????????????????????????" cat-2046 [004] ..... 530.934563: foo: (do_sys_openat2+0x0/0x240) arg1="??????????????????????????????????????? ---truncated---	(en) In the Linux kernel, the following vulnerability has been resolved: tracing: Free buffers when a used dynamic event is removed After 65536 dynamic events have been added and removed, the "type" field of the event then uses the first type number that is available (not currently used by other events). A type number is the identifier of the binary blobs in the tracing ring buffer (known as events) to map them to logic that can parse the binary blob. The issue is that if a dynamic event (like a kprobe event) is traced and is in the ring buffer, and then that event is removed (because it is dynamic, which means it can be created and destroyed), if another dynamic event is created that has the same number that new event's logic on parsing the binary blob will be used. To show how this can be an issue, the following can crash the kernel: # cd /sys/kernel/tracing # for i in `seq 65536`; do echo 'p:kprobes/foo do_sys_openat2 $arg1:u32' > kprobe_events # done For every iteration of the above, the writing to the kprobe_events will remove the old event and create a new one (with the same format) and increase the type number to the next available on until the type number reaches over 65535 which is the max number for the 16 bit type. After it reaches that number, the logic to allocate a new number simply looks for the next available number. When an dynamic event is removed, that number is then available to be reused by the next dynamic event created. That is, once the above reaches the max number, the number assigned to the event in that loop will remain the same. Now that means deleting one dynamic event and created another will reuse the previous events type number. This is where bad things can happen. After the above loop finishes, the kprobes/foo event which reads the do_sys_openat2 function call's first parameter as an integer. # echo 1 > kprobes/foo/enable # cat /etc/passwd > /dev/null # cat trace cat-2211 [005] .... 2007.849603: foo: (do_sys_openat2+0x0/0x130) arg1=4294967196 cat-2211 [005] .... 2007.849620: foo: (do_sys_openat2+0x0/0x130) arg1=4294967196 cat-2211 [005] .... 2007.849838: foo: (do_sys_openat2+0x0/0x130) arg1=4294967196 cat-2211 [005] .... 2007.849880: foo: (do_sys_openat2+0x0/0x130) arg1=4294967196 # echo 0 > kprobes/foo/enable Now if we delete the kprobe and create a new one that reads a string: # echo 'p:kprobes/foo do_sys_openat2 +0($arg2):string' > kprobe_events And now we can the trace: # cat trace sendmail-1942 [002] ..... 530.136320: foo: (do_sys_openat2+0x0/0x240) arg1= cat-2046 [004] ..... 530.930817: foo: (do_sys_openat2+0x0/0x240) arg1="��" cat-2046 [004] ..... 530.930961: foo: (do_sys_openat2+0x0/0x240) arg1="��" cat-2046 [004] ..... 530.934278: foo: (do_sys_openat2+0x0/0x240) arg1="��" cat-2046 [004] ..... 530.934563: foo: (do_sys_openat2+0x0/0x240) arg1="�� ---truncated---

25 Oct 2024, 14:30

Type	Values Removed	Values Added
CWE		CWE-416
CVSS	v2 : ~~unknown~~ v3 : ~~unknown~~	v2 : unknown v3 : 7.8
References	~~() https://git.kernel.org/stable/c/1603feac154ff38514e8354e3079a455eb4801e2 -~~	() https://git.kernel.org/stable/c/1603feac154ff38514e8354e3079a455eb4801e2 - Patch
References	~~() https://git.kernel.org/stable/c/417d5ea6e735e5d88ffb6c436cf2938f3f476dd1 -~~	() https://git.kernel.org/stable/c/417d5ea6e735e5d88ffb6c436cf2938f3f476dd1 - Patch
References	~~() https://git.kernel.org/stable/c/4313e5a613049dfc1819a6dfb5f94cf2caff9452 -~~	() https://git.kernel.org/stable/c/4313e5a613049dfc1819a6dfb5f94cf2caff9452 - Patch
References	~~() https://git.kernel.org/stable/c/be111ebd8868d4b7c041cb3c6102e1ae27d6dc1d -~~	() https://git.kernel.org/stable/c/be111ebd8868d4b7c041cb3c6102e1ae27d6dc1d - Patch
References	~~() https://git.kernel.org/stable/c/c52d0c8c4f38f7580cff61c4dfe1034c580cedfd -~~	() https://git.kernel.org/stable/c/c52d0c8c4f38f7580cff61c4dfe1034c580cedfd - Patch
First Time		Linux linux Kernel Linux
CPE		cpe:2.3:o:linux:linux_kernel:6.1:rc3:::::: cpe:2.3:o:linux:linux_kernel:::::::: cpe:2.3:o:linux:linux_kernel:6.1:rc1:::::: cpe:2.3:o:linux:linux_kernel:6.1:rc7:::::: cpe:2.3:o:linux:linux_kernel:6.1:rc2:::::: cpe:2.3:o:linux:linux_kernel:6.1:rc6:::::: cpe:2.3:o:linux:linux_kernel:6.1:rc4:::::: cpe:2.3:o:linux:linux_kernel:6.1:rc5::::::

23 Oct 2024, 15:13

Type	Values Removed	Values Added
Summary		(es) En el kernel de Linux, se ha resuelto la siguiente vulnerabilidad: rastreo: Búferes libres cuando se elimina un evento dinámico usado Después de que se hayan agregado y eliminado 65536 eventos dinámicos, el campo "tipo" del evento usa el primer número de tipo que está disponible (no usado actualmente por otros eventos). Un número de tipo es el identificador de los blobs binarios en el búfer de anillo de rastreo (conocidos como eventos) para mapearlos a la lógica que puede analizar el blob binario. El problema es que si se rastrea un evento dinámico (como un evento kprobe) y está en el búfer de anillo, y luego ese evento se elimina (porque es dinámico, lo que significa que se puede crear y destruir), si se crea otro evento dinámico que tenga el mismo número, se usará la lógica de ese nuevo evento al analizar el blob binario. Para mostrar cómo esto puede ser un problema, lo siguiente puede bloquear el kernel: # cd /sys/kernel/tracing # for i in `seq 65536`; Para cada iteración de lo anterior, la escritura en kprobe_events eliminará el evento anterior y creará uno nuevo (con el mismo formato) y aumentará el número de tipo al siguiente disponible hasta que el número de tipo alcance más de 65535, que es el número máximo para el tipo de 16 bits. Después de que alcanza ese número, la lógica para asignar un nuevo número simplemente busca el siguiente número disponible. Cuando se elimina un evento dinámico, ese número está disponible para ser reutilizado por el próximo evento dinámico creado. Es decir, una vez que lo anterior alcanza el número máximo, el número asignado al evento en ese bucle seguirá siendo el mismo. Ahora, eso significa que eliminar un evento dinámico y crear otro reutilizará el número de tipo de eventos anteriores. Aquí es donde pueden suceder cosas malas. Después de que finaliza el bucle anterior, el evento kprobes/foo que lee el primer parámetro de la llamada a la función do_sys_openat2 como un entero. # echo 1 > kprobes/foo/enable # cat /etc/passwd > /dev/null # cat seguimiento cat-2211 [005] .... 2007.849603: foo: (do_sys_openat2+0x0/0x130) arg1=4294967196 cat-2211 [005] .... 2007.849620: foo: (do_sys_openat2+0x0/0x130) arg1=4294967196 cat-2211 [005] .... 2007.849838: foo: (do_sys_openat2+0x0/0x130) arg1=4294967196 cat-2211 [005] .... 2007.849880: foo: (do_sys_openat2+0x0/0x130) arg1=4294967196 # echo 0 > kprobes/foo/enable Ahora si borramos el kprobe y creamos uno nuevo que lea una cadena: # echo 'p:kprobes/foo do_sys_openat2 +0($arg2):string' > kprobe_events Y ahora podemos hacer el trace: # cat trace sendmail-1942 [002] ..... 530.136320: foo: (do_sys_openat2+0x0/0x240) arg1= cat-2046 [004] ..... 530.930817: foo: (do_sys_openat2+0x0/0x240) arg1="????????????????????????????????????????????? ????????????????????????????????????????????????????????????????" cat-2046 [004] ..... 530.930961: foo: (do_sys_openat2+0x0/0x240) arg1="????????????????????????????????????????????? ??????????????????????????????????????????????????????????????????" cat-2046 [004] ..... 530.934278: foo: (do_sys_openat2+0x0/0x240) arg1="????????????????????????????????????????????? ??????????????????????????????????????????????????" cat-2046 [004] ..... 530.934563: foo: (do_sys_openat2+0x0/0x240) arg1="????????????????????????????????????????? ---truncado---
Summary	(en) In the Linux kernel, the following vulnerability has been resolved: tracing: Free buffers when a used dynamic event is removed After 65536 dynamic events have been added and removed, the "type" field of the event then uses the first type number that is available (not currently used by other events). A type number is the identifier of the binary blobs in the tracing ring buffer (known as events) to map them to logic that can parse the binary blob. The issue is that if a dynamic event (like a kprobe event) is traced and is in the ring buffer, and then that event is removed (because it is dynamic, which means it can be created and destroyed), if another dynamic event is created that has the same number that new event's logic on parsing the binary blob will be used. To show how this can be an issue, the following can crash the kernel: # cd /sys/kernel/tracing # for i in `seq 65536`; do echo 'p:kprobes/foo do_sys_openat2 $arg1:u32' > kprobe_events # done For every iteration of the above, the writing to the kprobe_events will remove the old event and create a new one (with the same format) and increase the type number to the next available on until the type number reaches over 65535 which is the max number for the 16 bit type. After it reaches that number, the logic to allocate a new number simply looks for the next available number. When an dynamic event is removed, that number is then available to be reused by the next dynamic event created. That is, once the above reaches the max number, the number assigned to the event in that loop will remain the same. Now that means deleting one dynamic event and created another will reuse the previous events type number. This is where bad things can happen. After the above loop finishes, the kprobes/foo event which reads the do_sys_openat2 function call's first parameter as an integer. # echo 1 > kprobes/foo/enable # cat /etc/passwd > /dev/null # cat trace cat-2211 [005] .... 2007.849603: foo: (do_sys_openat2+0x0/0x130) arg1=4294967196 cat-2211 [005] .... 2007.849620: foo: (do_sys_openat2+0x0/0x130) arg1=4294967196 cat-2211 [005] .... 2007.849838: foo: (do_sys_openat2+0x0/0x130) arg1=4294967196 cat-2211 [005] .... 2007.849880: foo: (do_sys_openat2+0x0/0x130) arg1=4294967196 # echo 0 > kprobes/foo/enable Now if we delete the kprobe and create a new one that reads a string: # echo 'p:kprobes/foo do_sys_openat2 +0($arg2):string' > kprobe_events And now we can the trace: # cat trace sendmail-1942 [002] ..... 530.136320: foo: (do_sys_openat2+0x0/0x240) arg1= cat-2046 [004] ..... 530.930817: foo: (do_sys_openat2+0x0/0x240) arg1="��" cat-2046 [004] ..... 530.930961: foo: (do_sys_openat2+0x0/0x240) arg1="��" cat-2046 [004] ..... 530.934278: foo: (do_sys_openat2+0x0/0x240) arg1="��" cat-2046 [004] ..... 530.934563: foo: (do_sys_openat2+0x0/0x240) arg1="�� ---truncated---	(en) In the Linux kernel, the following vulnerability has been resolved: tracing: Free buffers when a used dynamic event is removed After 65536 dynamic events have been added and removed, the "type" field of the event then uses the first type number that is available (not currently used by other events). A type number is the identifier of the binary blobs in the tracing ring buffer (known as events) to map them to logic that can parse the binary blob. The issue is that if a dynamic event (like a kprobe event) is traced and is in the ring buffer, and then that event is removed (because it is dynamic, which means it can be created and destroyed), if another dynamic event is created that has the same number that new event's logic on parsing the binary blob will be used. To show how this can be an issue, the following can crash the kernel: # cd /sys/kernel/tracing # for i in `seq 65536`; do echo 'p:kprobes/foo do_sys_openat2 $arg1:u32' > kprobe_events # done For every iteration of the above, the writing to the kprobe_events will remove the old event and create a new one (with the same format) and increase the type number to the next available on until the type number reaches over 65535 which is the max number for the 16 bit type. After it reaches that number, the logic to allocate a new number simply looks for the next available number. When an dynamic event is removed, that number is then available to be reused by the next dynamic event created. That is, once the above reaches the max number, the number assigned to the event in that loop will remain the same. Now that means deleting one dynamic event and created another will reuse the previous events type number. This is where bad things can happen. After the above loop finishes, the kprobes/foo event which reads the do_sys_openat2 function call's first parameter as an integer. # echo 1 > kprobes/foo/enable # cat /etc/passwd > /dev/null # cat trace cat-2211 [005] .... 2007.849603: foo: (do_sys_openat2+0x0/0x130) arg1=4294967196 cat-2211 [005] .... 2007.849620: foo: (do_sys_openat2+0x0/0x130) arg1=4294967196 cat-2211 [005] .... 2007.849838: foo: (do_sys_openat2+0x0/0x130) arg1=4294967196 cat-2211 [005] .... 2007.849880: foo: (do_sys_openat2+0x0/0x130) arg1=4294967196 # echo 0 > kprobes/foo/enable Now if we delete the kprobe and create a new one that reads a string: # echo 'p:kprobes/foo do_sys_openat2 +0($arg2):string' > kprobe_events And now we can the trace: # cat trace sendmail-1942 [002] ..... 530.136320: foo: (do_sys_openat2+0x0/0x240) arg1= cat-2046 [004] ..... 530.930817: foo: (do_sys_openat2+0x0/0x240) arg1="????????????????????????????????????????????????????????????????????????????????????????????????" cat-2046 [004] ..... 530.930961: foo: (do_sys_openat2+0x0/0x240) arg1="????????????????????????????????????????????????????????????????????????????????????????????????" cat-2046 [004] ..... 530.934278: foo: (do_sys_openat2+0x0/0x240) arg1="????????????????????????????????????????????????????????????????????????????????????????????????" cat-2046 [004] ..... 530.934563: foo: (do_sys_openat2+0x0/0x240) arg1="??????????????????????????????????????? ---truncated---

21 Oct 2024, 20:15

Type	Values Removed	Values Added
New CVE

7.8^/10

Attack Vector LOCAL

Attack Complexity LOW

Privileges Required LOW

User Interaction NONE

Confidentiality Impact HIGH

Integrity Impact HIGH

Availability Impact HIGH

Scope UNCHANGED