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CVE-2024-44987: ipv6: prevent UAF in ip6_send_skb()

Description

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

ipv6: prevent UAF in ip6_send_skb()

syzbot reported an UAF in ip6_send_skb() [1]

After ip6_local_out() has returned, we no longer can safely
dereference rt, unless we hold rcu_read_lock().

A similar issue has been fixed in commit
a688caa34beb ("ipv6: take rcu lock in rawv6_send_hdrinc()")

Another potential issue in ip6_finish_output2() is handled in a
separate patch.

[1]
BUG: KASAN: slab-use-after-free in ip6_send_skb+0x18d/0x230 net/ipv6/ip6_output.c:1964
Read of size 8 at addr ffff88806dde4858 by task syz.1.380/6530

CPU: 1 UID: 0 PID: 6530 Comm: syz.1.380 Not tainted 6.11.0-rc3-syzkaller-00306-gdf6cbc62cc9b #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/06/2024
Call Trace:

__dump_stack lib/dump_stack.c:93 [inline]
dump_stack_lvl+0x241/0x360 lib/dump_stack.c:119
print_address_description mm/kasan/report.c:377 [inline]
print_report+0x169/0x550 mm/kasan/report.c:488
kasan_report+0x143/0x180 mm/kasan/report.c:601
ip6_send_skb+0x18d/0x230 net/ipv6/ip6_output.c:1964
rawv6_push_pending_frames+0x75c/0x9e0 net/ipv6/raw.c:588
rawv6_sendmsg+0x19c7/0x23c0 net/ipv6/raw.c:926
sock_sendmsg_nosec net/socket.c:730 [inline]
__sock_sendmsg+0x1a6/0x270 net/socket.c:745
sock_write_iter+0x2dd/0x400 net/socket.c:1160
do_iter_readv_writev+0x60a/0x890
vfs_writev+0x37c/0xbb0 fs/read_write.c:971
do_writev+0x1b1/0x350 fs/read_write.c:1018
do_syscall_x64 ar...

Classification

CVE ID: CVE-2024-44987

Affected Products

Vendor: Linux

Product: Linux

Exploit Prediction Scoring System (EPSS)

EPSS Score: 0.05% (probability of being exploited)

EPSS Percentile: 13.76% (scored less or equal to compared to others)

EPSS Date: 2025-06-02 (when was this score calculated)

Stakeholder-Specific Vulnerability Categorization (SSVC)

SSVC Exploitation: none

SSVC Technical Impact: partial

SSVC Automatable: false

References

Timeline

2025-03-14 11:00:37 UTC
Tenable Plugins

Amazon Linux 2 : kernel (ALAS-2024-2696)
2025-05-04 10:40:17 UTC
CVE

ipv6: prevent UAF in ip6_send_skb()