CVE-2026-43465
- Source
- https://cve.org/CVERecord?id=CVE-2026-43465
- Import Source
- https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-43465.json
- JSON Data
- https://api.osv.dev/v1/vulns/CVE-2026-43465
- Downstream
- Published
- 2026-05-08T14:22:26.822Z
- Modified
- 2026-07-08T08:13:30.512000199Z
- Severity
-
- 9.8 (Critical) CVSS_V3 - CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H CVSS Calculator
- Summary
- net/mlx5e: RX, Fix XDP multi-buf frag counting for striding RQ
- Details
-
In the Linux kernel, the following vulnerability has been resolved:
net/mlx5e: RX, Fix XDP multi-buf frag counting for striding RQ
XDP multi-buf programs can modify the layout of the XDP buffer when the program calls bpfxdppulldata() or bpfxdpadjusttail(). The referenced commit in the fixes tag corrected the assumption in the mlx5 driver that the XDP buffer layout doesn't change during a program execution. However, this fix introduced another issue: the dropped fragments still need to be counted on the driver side to avoid page fragment reference counting issues.
The issue was discovered by the drivers/net/xdp.py selftest, more specifically the testxdpnativetxmb: - The mlx5 driver allocates a pagepool page and initializes it with a frag counter of 64 (pprefcount=64) and the internal frag counter to 0. - The test sends one packet with no payload. - On RX (mlx5eskbfromcqempwrqnonlinear()), mlx5 configures the XDP buffer with the packet data starting in the first fragment which is the page mentioned above. - The XDP program runs and calls bpfxdppulldata() which moves the header into the linear part of the XDP buffer. As the packet doesn't contain more data, the program drops the tail fragment since it no longer contains any payload (pprefcount=63). - mlx5 device skips counting this fragment. Internal frag counter remains 0. - mlx5 releases all 64 fragments of the page but page ppref_count is 63 => negative reference counting error.
Resulting splat during the test:
WARNING: CPU: 0 PID: 188225 at ./include/net/pagepool/helpers.h:297 mlx5epagereleasefragmented.isra.0+0xbd/0xe0 [mlx5core] Modules linked in: [...] CPU: 0 UID: 0 PID: 188225 Comm: ip Not tainted 6.18.0-rc7forupstreammindebug202512081144 #1 NONE Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS rel-1.13.0-0-gf21b5a4aeb02-prebuilt.qemu.org 04/01/2014 RIP: 0010:mlx5epagereleasefragmented.isra.0+0xbd/0xe0 [mlx5core] [...] Call Trace: <TASK> mlx5efreerxmpwqe+0x20a/0x250 [mlx5core] mlx5edeallocrxmpwqe+0x37/0xb0 [mlx5core] mlx5efreerxdescs+0x11a/0x170 [mlx5core] mlx5ecloserq+0x78/0xa0 [mlx5core] mlx5eclosequeues+0x46/0x2a0 [mlx5core] mlx5eclosechannel+0x24/0x90 [mlx5core] mlx5eclosechannels+0x5d/0xf0 [mlx5core] mlx5esafeswitchparams+0x2ec/0x380 [mlx5core] mlx5echangemtu+0x11d/0x490 [mlx5core] mlx5echangenicmtu+0x19/0x30 [mlx5core] netifsetmtuext+0xfc/0x240 dosetlink.isra.0+0x226/0x1100 rtnlnewlink+0x7a9/0xba0 rtnetlinkrcvmsg+0x220/0x3c0 netlinkrcvskb+0x4b/0xf0 netlinkunicast+0x255/0x380 netlinksendmsg+0x1f3/0x420 __sock_sendmsg+0x38/0x60 ____sys_sendmsg+0x1e8/0x240 ___sys_sendmsg+0x7c/0xb0 [...] _syssendmsg+0x5f/0xb0 dosyscall64+0x55/0xc70
The problem applies for XDP_PASS as well which is handled in a different code path in the driver.
This patch fixes the issue by doing page frag counting on all the original XDP buffer fragments for all relevant XDP actions (XDPTX , XDPREDIRECT and XDP_PASS). This is basically reverting to the original counting before the commit in the fixes tag.
As fragpage is still pointing to the original tail, the nrfrags parameter to xdpupdateskbfragsinfo() needs to be calculated in a different way to reflect the new nr_frags.
- Database specific
{ "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/43xxx/CVE-2026-43465.json", "cna_assigner": "Linux" }- References
-
- https://git.kernel.org/stable/c/043bd62f748bc9fd98154037aa598cffbd3c667c
- https://git.kernel.org/stable/c/7d7342a18fadcdb70a63b3c930dc63528ce51832
- https://git.kernel.org/stable/c/db25c42c2e1f9c0d136420fff5e5700f7e771a6f
- https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/43xxx/CVE-2026-43465.json
- https://nvd.nist.gov/vuln/detail/CVE-2026-43465
- https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
Affected packages
Git / git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
Affected ranges
- Type
- GIT
- Repo
- https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
- Events
-
Introduced87bcef158ac1faca1bd7e0104588e8e2956d10beFixed7d7342a18fadcdb70a63b3c930dc63528ce51832Fixed043bd62f748bc9fd98154037aa598cffbd3c667cFixeddb25c42c2e1f9c0d136420fff5e5700f7e771a6f
- Type
- GIT
- Repo
- https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
- Events
-
Introduced0 Unknown introduced commit / All previous commits are affectedLast affected8b051d7f530e8a5237da242fbeafef02fec6b813Last affectedcb9edd583e23979ee546981be963ad5f217e8b18Last affectedf2557d7fa38e9475b38588f5c124476091480f53
- Type
- GIT
- Repo
- https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
- Events
-
Introduced6.6.115Fixed6.7
- Type
- GIT
- Repo
- https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
- Events
-
Introduced6.12.56Fixed6.13
- Type
- GIT
- Repo
- https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
- Events
-
Introduced6.17.6Fixed6.18