| From bippy-5f407fcff5a0 Mon Sep 17 00:00:00 2001 |
| From: Greg Kroah-Hartman <gregkh@linuxfoundation.org> |
| To: <linux-cve-announce@vger.kernel.org> |
| Reply-to: <cve@kernel.org>, <linux-kernel@vger.kernel.org> |
| Subject: CVE-2025-21703: netem: Update sch->q.qlen before qdisc_tree_reduce_backlog() |
| |
| Description |
| =========== |
| |
| In the Linux kernel, the following vulnerability has been resolved: |
| |
| netem: Update sch->q.qlen before qdisc_tree_reduce_backlog() |
| |
| qdisc_tree_reduce_backlog() notifies parent qdisc only if child |
| qdisc becomes empty, therefore we need to reduce the backlog of the |
| child qdisc before calling it. Otherwise it would miss the opportunity |
| to call cops->qlen_notify(), in the case of DRR, it resulted in UAF |
| since DRR uses ->qlen_notify() to maintain its active list. |
| |
| The Linux kernel CVE team has assigned CVE-2025-21703 to this issue. |
| |
| |
| Affected and fixed versions |
| =========================== |
| |
| Issue introduced in 5.4.288 with commit 83c6ab12f08dcc09d4c5ac86fdb89736b28f1d31 and fixed in 5.4.291 with commit e395fec75ac2dbffc99b4bce57b7f1f3c5449f2c |
| Issue introduced in 5.10.232 with commit 216509dda290f6db92c816dd54b83c1df9da9e76 and fixed in 5.10.235 with commit 7f31d74fcc556a9166b1bb20515542de7bb939d1 |
| Issue introduced in 5.15.175 with commit c2047b0e216c8edce227d7c42f99ac2877dad0e4 and fixed in 5.15.179 with commit 98a2c685293aae122f688cde11d9334dddc5d207 |
| Issue introduced in 6.1.121 with commit 10df49cfca73dfbbdb6c4150d859f7e8926ae427 and fixed in 6.1.129 with commit 7b79ca9a1de6a428d486ff52fb3d602321c08f55 |
| Issue introduced in 6.6.67 with commit 3824c5fad18eeb7abe0c4fc966f29959552dca3e and fixed in 6.6.78 with commit 1f8e3f4a4b8b90ad274dfbc66fc7d55cb582f4d5 |
| Issue introduced in 6.12.6 with commit 356078a5c55ec8d2061fcc009fb8599f5b0527f9 and fixed in 6.12.14 with commit 6312555249082d6d8cc5321ff725df05482d8b83 |
| Issue introduced in 6.13 with commit f8d4bc455047cf3903cd6f85f49978987dbb3027 and fixed in 6.13.3 with commit 839ecc583fa00fab785fde1c85a326743657fd32 |
| Issue introduced in 6.13 with commit f8d4bc455047cf3903cd6f85f49978987dbb3027 and fixed in 6.14 with commit 638ba5089324796c2ee49af10427459c2de35f71 |
| |
| Please see https://www.kernel.org for a full list of currently supported |
| kernel versions by the kernel community. |
| |
| Unaffected versions might change over time as fixes are backported to |
| older supported kernel versions. The official CVE entry at |
| https://cve.org/CVERecord/?id=CVE-2025-21703 |
| will be updated if fixes are backported, please check that for the most |
| up to date information about this issue. |
| |
| |
| Affected files |
| ============== |
| |
| The file(s) affected by this issue are: |
| net/sched/sch_netem.c |
| |
| |
| Mitigation |
| ========== |
| |
| The Linux kernel CVE team recommends that you update to the latest |
| stable kernel version for this, and many other bugfixes. Individual |
| changes are never tested alone, but rather are part of a larger kernel |
| release. Cherry-picking individual commits is not recommended or |
| supported by the Linux kernel community at all. If however, updating to |
| the latest release is impossible, the individual changes to resolve this |
| issue can be found at these commits: |
| https://git.kernel.org/stable/c/e395fec75ac2dbffc99b4bce57b7f1f3c5449f2c |
| https://git.kernel.org/stable/c/7f31d74fcc556a9166b1bb20515542de7bb939d1 |
| https://git.kernel.org/stable/c/98a2c685293aae122f688cde11d9334dddc5d207 |
| https://git.kernel.org/stable/c/7b79ca9a1de6a428d486ff52fb3d602321c08f55 |
| https://git.kernel.org/stable/c/1f8e3f4a4b8b90ad274dfbc66fc7d55cb582f4d5 |
| https://git.kernel.org/stable/c/6312555249082d6d8cc5321ff725df05482d8b83 |
| https://git.kernel.org/stable/c/839ecc583fa00fab785fde1c85a326743657fd32 |
| https://git.kernel.org/stable/c/638ba5089324796c2ee49af10427459c2de35f71 |
