CVE-2022-49006

published 2024-10-21

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…

Priority P3 38 high 7.8 CVSS 3.1

AV L AC L PR L UI N S U C H I H A H

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) arg

Affected

16 ranges

Vendor	Product	Version range	Fixed in
debian	linux	< linux 6.0.12-1 (bookworm)	linux 6.0.12-1 (bookworm)
linux	linux	—	—
linux	linux	>= 77b44d1b7c28360910cdbd427fb62d485c08674c < 1603feac154ff38514e8354e3079a455eb4801e2	1603feac154ff38514e8354e3079a455eb4801e2
linux	linux	>= 77b44d1b7c28360910cdbd427fb62d485c08674c < be111ebd8868d4b7c041cb3c6102e1ae27d6dc1d	be111ebd8868d4b7c041cb3c6102e1ae27d6dc1d
linux	linux	>= 77b44d1b7c28360910cdbd427fb62d485c08674c < 417d5ea6e735e5d88ffb6c436cf2938f3f476dd1	417d5ea6e735e5d88ffb6c436cf2938f3f476dd1
linux	linux	>= 77b44d1b7c28360910cdbd427fb62d485c08674c < c52d0c8c4f38f7580cff61c4dfe1034c580cedfd	c52d0c8c4f38f7580cff61c4dfe1034c580cedfd
linux	linux	>= 77b44d1b7c28360910cdbd427fb62d485c08674c < 4313e5a613049dfc1819a6dfb5f94cf2caff9452	4313e5a613049dfc1819a6dfb5f94cf2caff9452
linux	linux_kernel	—	—
linux	linux_kernel	>= 0 < 5.10.158-1	5.10.158-1
linux	linux_kernel	>= 0 < 6.0.12-1	6.0.12-1
linux	linux_kernel	>= 0 < 6.0.12-1	6.0.12-1
linux	linux_kernel	>= 0 < 6.0.12-1	6.0.12-1
linux	linux_kernel	>= 2.6.33 < 5.4.226	5.4.226
linux	linux_kernel	>= 5.11 < 5.15.82	5.15.82
linux	linux_kernel	>= 5.16 < 6.0.12	6.0.12
linux	linux_kernel	>= 5.5 < 5.10.158	5.10.158

CVSS provenance

nvd v3.1 7.8 HIGH CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

osv 7.8 HIGH

vendor_debian 7.8 HIGH

vendor_redhat 7.8 HIGH

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