CVE-2024-35982
Assigner: Linux
Published: 2024-05-20T09:42:06.397Z
State: PUBLISHED
descriptions: value: In the Linux kernel, the following vulnerability has been resolved:

batman-adv: Avoid infinite loop trying to resize local TT

If the MTU of one of an attached interface becomes too small to transmit
the local translation table then it must be resized to fit inside all
fragments (when enabled) or a single packet.

But if the MTU becomes too low to transmit even the header + the VLAN
specific part then the resizing of the local TT will never succeed. This
can for example happen when the usable space is 110 bytes and 11 VLANs are
on top of batman-adv. In this case, at least 116 byte would be needed.
There will just be an endless spam of

   batman_adv: batadv0: Forced to purge local tt entries to fit new maximum fragment MTU (110)

in the log but the function will never finish. Problem here is that the
timeout will be halved all the time and will then stagnate at 0 and
therefore never be able to reduce the table even more.

There are other scenarios possible with a similar result. The number of
BATADV_TT_CLIENT_NOPURGE entries in the local TT can for example be too
high to fit inside a packet. Such a scenario can therefore happen also with
only a single VLAN + 7 non-purgable addresses - requiring at least 120
bytes.

While this should be handled proactively when:

* interface with too low MTU is added
* VLAN is added
* non-purgeable local mac is added
* MTU of an attached interface is reduced
* fragmentation setting gets disabled (which most likely requires dropping
  attached interfaces)

not all of these scenarios can be prevented because batman-adv is only
consuming events without the the possibility to prevent these actions
(non-purgable MAC address added, MTU of an attached interface is reduced).
It is therefore necessary to also make sure that the code is able to handle
also the situations when there were already incompatible system
configuration are present.
affected: product: Linux
vendor: Linux
defaultStatus: unaffected
repo: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
versions: version: a19d3d85e1b8
lessThan: 04720ea2e6c6
status: affected
versionType: git
version: a19d3d85e1b8
lessThan: b3ddf6904073
status: affected
versionType: git
version: a19d3d85e1b8
lessThan: 70a8be9dc2fb
status: affected
versionType: git
version: a19d3d85e1b8
lessThan: 87b6af1a7683
status: affected
versionType: git
version: a19d3d85e1b8
lessThan: 3fe79b2c8346
status: affected
versionType: git
version: a19d3d85e1b8
lessThan: 4ca2a5fb54ea
status: affected
versionType: git
version: a19d3d85e1b8
lessThan: ca54e2671548
status: affected
versionType: git
version: a19d3d85e1b8
lessThan: b1f532a3b1e6
status: affected
versionType: git
product: Linux
vendor: Linux
defaultStatus: affected
repo: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
versions: version: 3.13
status: affected
version: 0
lessThan: 3.13
status: unaffected
versionType: custom
version: 4.19.313
lessThanOrEqual: 4.19.*
status: unaffected
versionType: custom
version: 5.4.275
lessThanOrEqual: 5.4.*
status: unaffected
versionType: custom
version: 5.10.216
lessThanOrEqual: 5.10.*
status: unaffected
versionType: custom
version: 5.15.156
lessThanOrEqual: 5.15.*
status: unaffected
versionType: custom
version: 6.1.87
lessThanOrEqual: 6.1.*
status: unaffected
versionType: custom
version: 6.6.28
lessThanOrEqual: 6.6.*
status: unaffected
versionType: custom
version: 6.8.7
lessThanOrEqual: 6.8.*
status: unaffected
versionType: custom
version: 6.9
lessThanOrEqual: *
status: unaffected
versionType: original_commit_for_fix
title: batman-adv: Avoid infinite loop trying to resize local TT
x_generator: engine: bippy-d175d3acf727