vulnerability

Ubuntu: (Multiple Advisories) (CVE-2025-21868): Linux kernel vulnerabilities

Severity
5
CVSS
(AV:L/AC:L/Au:S/C:N/I:N/A:C)
Published
Mar 27, 2025
Added
May 21, 2025
Modified
May 29, 2025

Description

In the Linux kernel, the following vulnerability has been resolved:

net: allow small head cache usage with large MAX_SKB_FRAGS values

Sabrina reported the following splat:

WARNING: CPU: 0 PID: 1 at net/core/dev.c:6935 netif_napi_add_weight_locked+0x8f2/0xba0
Modules linked in:
CPU: 0 UID: 0 PID: 1 Comm: swapper/0 Not tainted 6.14.0-rc1-net-00092-g011b03359038 #996
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Arch Linux 1.16.3-1-1 04/01/2014
RIP: 0010:netif_napi_add_weight_locked+0x8f2/0xba0
Code: e8 c3 e6 6a fe 48 83 c4 28 5b 5d 41 5c 41 5d 41 5e 41 5f c3 cc cc cc cc c7 44 24 10 ff ff ff ff e9 8f fb ff ff e8 9e e6 6a fe 0b e9 d3 fe ff ff e8 92 e6 6a fe 48 8b 04 24 be ff ff ff ff 48
RSP: 0000:ffffc9000001fc60 EFLAGS: 00010293
RAX: 0000000000000000 RBX: ffff88806ce48128 RCX: 1ffff11001664b9e
RDX: ffff888008f00040 RSI: ffffffff8317ca42 RDI: ffff88800b325cb6
RBP: ffff88800b325c40 R08: 0000000000000001 R09: ffffed100167502c
R10: ffff88800b3a8163 R11: 0000000000000000 R12: ffff88800ac1c168
R13: ffff88800ac1c168 R14: ffff88800ac1c168 R15: 0000000000000007
FS: 0000000000000000(0000) GS:ffff88806ce00000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: ffff888008201000 CR3: 0000000004c94001 CR4: 0000000000370ef0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:

gro_cells_init+0x1ba/0x270
xfrm_input_init+0x4b/0x2a0
xfrm_init+0x38/0x50
ip_rt_init+0x2d7/0x350
ip_init+0xf/0x20
inet_init+0x406/0x590
do_one_initcall+0x9d/0x2e0
do_initcalls+0x23b/0x280
kernel_init_freeable+0x445/0x490
kernel_init+0x20/0x1d0
ret_from_fork+0x46/0x80
ret_from_fork_asm+0x1a/0x30

irq event stamp: 584330
hardirqs last enabled at (584338): [] __up_console_sem+0x77/0xb0
hardirqs last disabled at (584345): [] __up_console_sem+0x5c/0xb0
softirqs last enabled at (583242): [] netlink_insert+0x14d/0x470
softirqs last disabled at (583754): [] netif_napi_add_weight_locked+0x77d/0xba0

on kernel built with MAX_SKB_FRAGS=45, where SKB_WITH_OVERHEAD(1024)
is smaller than GRO_MAX_HEAD.

Such built additionally contains the revert of the single page frag cache
so that napi_get_frags() ends up using the page frag allocator, triggering
the splat.

Note that the underlying issue is independent from the mentioned
revert; address it ensuring that the small head cache will fit either TCP
and GRO allocation and updating napi_alloc_skb() and __netdev_alloc_skb()
to select kmalloc() usage for any allocation fitting such cache.

Solution(s)

ubuntu-upgrade-linux-image-6-11-0-1010-realtimeubuntu-upgrade-linux-image-6-11-0-1013-raspiubuntu-upgrade-linux-image-6-11-0-1014-awsubuntu-upgrade-linux-image-6-11-0-1014-lowlatencyubuntu-upgrade-linux-image-6-11-0-1014-lowlatency-64kubuntu-upgrade-linux-image-6-11-0-1015-azureubuntu-upgrade-linux-image-6-11-0-1015-azure-fdeubuntu-upgrade-linux-image-6-11-0-1015-gcpubuntu-upgrade-linux-image-6-11-0-1015-gcp-64kubuntu-upgrade-linux-image-6-11-0-1016-oracleubuntu-upgrade-linux-image-6-11-0-1016-oracle-64kubuntu-upgrade-linux-image-6-11-0-1022-oemubuntu-upgrade-linux-image-6-11-0-26-genericubuntu-upgrade-linux-image-6-11-0-26-generic-64kubuntu-upgrade-linux-image-awsubuntu-upgrade-linux-image-azureubuntu-upgrade-linux-image-azure-fdeubuntu-upgrade-linux-image-gcpubuntu-upgrade-linux-image-gcp-64kubuntu-upgrade-linux-image-genericubuntu-upgrade-linux-image-generic-64kubuntu-upgrade-linux-image-generic-64k-hwe-24-04ubuntu-upgrade-linux-image-generic-hwe-24-04ubuntu-upgrade-linux-image-lowlatencyubuntu-upgrade-linux-image-lowlatency-64kubuntu-upgrade-linux-image-lowlatency-64k-hwe-24-04ubuntu-upgrade-linux-image-lowlatency-hwe-24-04ubuntu-upgrade-linux-image-oem-24-04bubuntu-upgrade-linux-image-oracleubuntu-upgrade-linux-image-oracle-64kubuntu-upgrade-linux-image-raspiubuntu-upgrade-linux-image-realtimeubuntu-upgrade-linux-image-virtualubuntu-upgrade-linux-image-virtual-hwe-24-04
Title
NEW

Explore Exposure Command

Confidently identify and prioritize exposures from endpoint to cloud with full attack surface visibility and threat-aware risk context.