// For flags

CVE-2024-44934

net: bridge: mcast: wait for previous gc cycles when removing port

Severity Score

"-"
*CVSS v-

Exploit Likelihood

*EPSS

Affected Versions

*CPE

Public Exploits

0
*Multiple Sources

Exploited in Wild

-
*KEV

Decision

Track
*SSVC
Descriptions

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

net: bridge: mcast: wait for previous gc cycles when removing port

syzbot hit a use-after-free[1] which is caused because the bridge doesn't
make sure that all previous garbage has been collected when removing a
port. What happens is:
CPU 1 CPU 2
start gc cycle remove port
acquire gc lock first
wait for lock
call br_multicasg_gc() directly
acquire lock now but free port
the port can be freed
while grp timers still
running

Make sure all previous gc cycles have finished by using flush_work before
freeing the port.

[1]
BUG: KASAN: slab-use-after-free in br_multicast_port_group_expired+0x4c0/0x550 net/bridge/br_multicast.c:861
Read of size 8 at addr ffff888071d6d000 by task syz.5.1232/9699

CPU: 1 PID: 9699 Comm: syz.5.1232 Not tainted 6.10.0-rc5-syzkaller-00021-g24ca36a562d6 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 06/07/2024
Call Trace:
<IRQ>
__dump_stack lib/dump_stack.c:88 [inline]
dump_stack_lvl+0x116/0x1f0 lib/dump_stack.c:114
print_address_description mm/kasan/report.c:377 [inline]
print_report+0xc3/0x620 mm/kasan/report.c:488
kasan_report+0xd9/0x110 mm/kasan/report.c:601
br_multicast_port_group_expired+0x4c0/0x550 net/bridge/br_multicast.c:861
call_timer_fn+0x1a3/0x610 kernel/time/timer.c:1792
expire_timers kernel/time/timer.c:1843 [inline]
__run_timers+0x74b/0xaf0 kernel/time/timer.c:2417
__run_timer_base kernel/time/timer.c:2428 [inline]
__run_timer_base kernel/time/timer.c:2421 [inline]
run_timer_base+0x111/0x190 kernel/time/timer.c:2437

*Credits: N/A
CVSS Scores
Attack Vector
-
Attack Complexity
-
Privileges Required
-
User Interaction
-
Scope
-
Confidentiality
-
Integrity
-
Availability
-
* Common Vulnerability Scoring System
SSVC
  • Decision:Track
Exploitation
None
Automatable
No
Tech. Impact
Partial
* Organization's Worst-case Scenario
Timeline
  • 2024-08-21 CVE Reserved
  • 2024-08-26 CVE Published
  • 2024-08-28 EPSS Updated
  • 2024-11-05 CVE Updated
  • ---------- Exploited in Wild
  • ---------- KEV Due Date
  • ---------- First Exploit
CWE
CAPEC
Affected Vendors, Products, and Versions
Vendor Product Version Other Status
Vendor Product Version Other Status <-- --> Vendor Product Version Other Status
Linux
Search vendor "Linux"
Linux Kernel
Search vendor "Linux" for product "Linux Kernel"
>= 5.10 < 5.15.165
Search vendor "Linux" for product "Linux Kernel" and version " >= 5.10 < 5.15.165"
en
Affected
Linux
Search vendor "Linux"
Linux Kernel
Search vendor "Linux" for product "Linux Kernel"
>= 5.10 < 6.1.105
Search vendor "Linux" for product "Linux Kernel" and version " >= 5.10 < 6.1.105"
en
Affected
Linux
Search vendor "Linux"
Linux Kernel
Search vendor "Linux" for product "Linux Kernel"
>= 5.10 < 6.6.46
Search vendor "Linux" for product "Linux Kernel" and version " >= 5.10 < 6.6.46"
en
Affected
Linux
Search vendor "Linux"
Linux Kernel
Search vendor "Linux" for product "Linux Kernel"
>= 5.10 < 6.10.5
Search vendor "Linux" for product "Linux Kernel" and version " >= 5.10 < 6.10.5"
en
Affected
Linux
Search vendor "Linux"
Linux Kernel
Search vendor "Linux" for product "Linux Kernel"
>= 5.10 < 6.11
Search vendor "Linux" for product "Linux Kernel" and version " >= 5.10 < 6.11"
en
Affected