Subject: CVE-2024-26754: gtp: fix use-after-free and null-ptr-deref in gtp_genl_dump_pdp()

From: Greg Kroah-Hartman <[email-masked]>

Description
===========

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

gtp: fix use-after-free and null-ptr-deref in gtp_genl_dump_pdp()

The gtp_net_ops pernet operations structure for the subsystem must be
registered before registering the generic netlink family.

Syzkaller hit 'general protection fault in gtp_genl_dump_pdp' bug:

general protection fault, probably for non-canonical address
0xdffffc0000000002: 0000 [#1] PREEMPT SMP KASAN NOPTI
KASAN: null-ptr-deref in range [0x0000000000000010-0x0000000000000017]
CPU: 1 PID: 5826 Comm: gtp Not tainted 6.8.0-rc3-std-def-alt1 #1
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.0-alt1 04/01/2014
RIP: 0010:gtp_genl_dump_pdp+0x1be/0x800 [gtp]
Code: c6 89 c6 e8 64 e9 86 df 58 45 85 f6 0f 85 4e 04 00 00 e8 c5 ee 86
      df 48 8b 54 24 18 48 b8 00 00 00 00 00 fc ff df 48 c1 ea 03 <80>
      3c 02 00 0f 85 de 05 00 00 48 8b 44 24 18 4c 8b 30 4c 39 f0 74
RSP: 0018:ffff888014107220 EFLAGS: 00010202
RAX: dffffc0000000000 RBX: 0000000000000000 RCX: 0000000000000000
RDX: 0000000000000002 RSI: 0000000000000000 RDI: 0000000000000000
RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000000
R13: ffff88800fcda588 R14: 0000000000000001 R15: 0000000000000000
FS:  00007f1be4eb05c0(0000) GS:ffff88806ce80000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f1be4e766cf CR3: 000000000c33e000 CR4: 0000000000750ef0
PKRU: 55555554
Call Trace:
 <TASK>
 ? show_regs+0x90/0xa0
 ? die_addr+0x50/0xd0
 ? exc_general_protection+0x148/0x220
 ? asm_exc_general_protection+0x22/0x30
 ? gtp_genl_dump_pdp+0x1be/0x800 [gtp]
 ? __alloc_skb+0x1dd/0x350
 ? __pfx___alloc_skb+0x10/0x10
 genl_dumpit+0x11d/0x230
 netlink_dump+0x5b9/0xce0
 ? lockdep_hardirqs_on_prepare+0x253/0x430
 ? __pfx_netlink_dump+0x10/0x10
 ? kasan_save_track+0x10/0x40
 ? __kasan_kmalloc+0x9b/0xa0
 ? genl_start+0x675/0x970
 __netlink_dump_start+0x6fc/0x9f0
 genl_family_rcv_msg_dumpit+0x1bb/0x2d0
 ? __pfx_genl_family_rcv_msg_dumpit+0x10/0x10
 ? genl_op_from_small+0x2a/0x440
 ? cap_capable+0x1d0/0x240
 ? __pfx_genl_start+0x10/0x10
 ? __pfx_genl_dumpit+0x10/0x10
 ? __pfx_genl_done+0x10/0x10
 ? security_capable+0x9d/0xe0

The Linux kernel CVE team has assigned CVE-2024-26754 to this issue.

Affected and fixed versions
===========================

	Issue introduced in 4.7 with commit 459aa660eb1d and fixed in 4.19.308 with commit f0ecdfa67918
	Issue introduced in 4.7 with commit 459aa660eb1d and fixed in 5.4.270 with commit f8cbd1791900
	Issue introduced in 4.7 with commit 459aa660eb1d and fixed in 5.10.211 with commit 2e534fd15e5c
	Issue introduced in 4.7 with commit 459aa660eb1d and fixed in 5.15.150 with commit a576308800be
	Issue introduced in 4.7 with commit 459aa660eb1d and fixed in 6.1.80 with commit 3963f16cc764
	Issue introduced in 4.7 with commit 459aa660eb1d and fixed in 6.6.19 with commit ba6b8b02a331
	Issue introduced in 4.7 with commit 459aa660eb1d and fixed in 6.7.7 with commit 5013bd54d283
	Issue introduced in 4.7 with commit 459aa660eb1d and fixed in 6.8 with commit 136cfaca2256

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-2024-26754
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:
	drivers/net/gtp.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/f0ecdfa679189d26aedfe24212d4e69e42c2c861
	https://git.kernel.org/stable/c/f8cbd1791900b5d96466eede8e9439a5b9ca4de7
	https://git.kernel.org/stable/c/2e534fd15e5c2ca15821c897352cf0e8a3e30dca
	https://git.kernel.org/stable/c/a576308800be28f2eaa099e7caad093b97d66e77
	https://git.kernel.org/stable/c/3963f16cc7643b461271989b712329520374ad2a
	https://git.kernel.org/stable/c/ba6b8b02a3314e62571a540efa96560888c5f03e
	https://git.kernel.org/stable/c/5013bd54d283eda5262c9ae3bcc966d01daf8576
	https://git.kernel.org/stable/c/136cfaca22567a03bbb3bf53a43d8cb5748b80ec