CVE-2025-38553
published 2025-08-19CVE-2025-38553: In the Linux kernel, the following vulnerability has been resolved: net/sched: Restrict conditions for adding duplicating netems to qdisc tree netem_enqueue's…
medium5.5CVSS 3.1
AVLACLPRLUINSUCNINAH
In the Linux kernel, the following vulnerability has been resolved:
net/sched: Restrict conditions for adding duplicating netems to qdisc tree
netem_enqueue's duplication prevention logic breaks when a netem
resides in a qdisc tree with other netems - this can lead to a
soft lockup and OOM loop in netem_dequeue, as seen in [1].
Ensure that a duplicating netem cannot exist in a tree with other
netems.
Previous approaches suggested in discussions in chronological order:
1) Track duplication status or ttl in the sk_buff struct. Considered
too specific a use case to extend such a struct, though this would
be a resilient fix and address other previous and potential future
DOS bugs like the one described in loopy fun [2].
2) Restrict netem_enqueue recursion depth like in act_mirred with a
per cpu variable. However, netem_dequeue can call enqueue on its
child, and the depth restriction could be bypassed if the child is a
netem.
3) Use the same approach as in 2, but add metadata in netem_skb_cb
to handle the netem_dequeue case and track a packet's involvement
in duplication. This is an overly complex approach, and Jamal
notes that the skb cb can be overwritten to circumvent this
safeguard.
4) Prevent the addition of a netem to a qdisc tree if its ancestral
path contains a netem. However, filters and actions can cause a
packet to change paths when re-enqueued to the root from netem
duplication, leading us to the current solution: prevent a
duplicating netem from inhabiting the same tree as other netems.
[1] https://lore.kernel.org/netdev/8DuRWwfqjoRDLDmBMlIfbrsZg9Gx50DHJc1ilxsEBNe2D6NMoigR_eIRIG0LOjMc3r10nUUZtArXx4oZBIdUfZQrwjcQhdinnMis_0G7VEk=@willsroot.io/
[2] https://lwn.net/Articles/719297/
Affected
42 ranges· showing 25
| Vendor | Product | Version range | Fixed in |
|---|---|---|---|
| debian | debian_linux | — | — |
| debian | linux | < linux 6.1.148-1 (bookworm) | linux 6.1.148-1 (bookworm) |
| debian | linux-6.1 | < linux 6.1.148-1 (bookworm) | linux 6.1.148-1 (bookworm) |
| linux | linux | — | — |
| linux | linux | >= 0afb51e72855971dba83b3c6b70c547c2d1161fd < ad340a4b4adb855b18b3666f26ad65c8968e2deb | ad340a4b4adb855b18b3666f26ad65c8968e2deb |
| linux | linux | >= 0afb51e72855971dba83b3c6b70c547c2d1161fd < f088b6ebe8797a3f948d2cae47f34bfb45cc6522 | f088b6ebe8797a3f948d2cae47f34bfb45cc6522 |
| linux | linux | >= 0afb51e72855971dba83b3c6b70c547c2d1161fd < cab2809944989889f88a1a8b5cff1c78460c72cb | cab2809944989889f88a1a8b5cff1c78460c72cb |
| linux | linux | >= 0afb51e72855971dba83b3c6b70c547c2d1161fd < 325f5ec67cc0a77f2d0d453445b9857f1cd06c76 | 325f5ec67cc0a77f2d0d453445b9857f1cd06c76 |
| linux | linux | >= 0afb51e72855971dba83b3c6b70c547c2d1161fd < 103c4e27ec9f5fe53022e46e976abf52c7221baf | 103c4e27ec9f5fe53022e46e976abf52c7221baf |
| linux | linux | >= 0afb51e72855971dba83b3c6b70c547c2d1161fd < 795cb393e38977aa991e70a9363da0ee734b2114 | 795cb393e38977aa991e70a9363da0ee734b2114 |
| linux | linux | >= 0afb51e72855971dba83b3c6b70c547c2d1161fd < 250f8796006c0f2bc638ce545f601d49ae8d528b | 250f8796006c0f2bc638ce545f601d49ae8d528b |
| linux | linux | >= 0afb51e72855971dba83b3c6b70c547c2d1161fd < 09317dfb681ac5a96fc69bea0c54441cf91b8270 | 09317dfb681ac5a96fc69bea0c54441cf91b8270 |
| linux | linux | >= 0afb51e72855971dba83b3c6b70c547c2d1161fd < ec8e0e3d7adef940cdf9475e2352c0680189d14e | ec8e0e3d7adef940cdf9475e2352c0680189d14e |
| linux | linux_kernel | — | — |
| linux | linux_kernel | >= 0 < 5.10.244-1 | 5.10.244-1 |
| linux | linux_kernel | >= 0 < 6.1.148-1 | 6.1.148-1 |
| linux | linux_kernel | >= 0 < 6.12.43-1 | 6.12.43-1 |
| linux | linux_kernel | >= 0 < 6.16.3-1 | 6.16.3-1 |
| linux | linux_kernel | >= 0 < 5.15.0-163.173 | 5.15.0-163.173 |
| linux | linux_kernel | >= 0 < 6.8.0-100.100 | 6.8.0-100.100 |
| linux | linux_kernel | >= 2.6.13 < 5.4.297 | 5.4.297 |
| linux | linux_kernel | >= 5.11 < 5.15.190 | 5.15.190 |
| linux | linux_kernel | >= 5.16 < 6.1.148 | 6.1.148 |
| linux | linux_kernel | >= 5.5 < 5.10.241 | 5.10.241 |
| linux | linux_kernel | >= 6.13 < 6.15.10 | 6.15.10 |
CVSS provenance
nvdv3.15.5MEDIUMCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
osv5.5MEDIUM