Linux: >> Linux Kernel >> 4.9.21 Security Vulnerabilities
In the Linux kernel, the following vulnerability has been resolved:
eventpoll: Fix semi-unbounded recursion
Ensure that epoll instances can never form a graph deeper than
EP_MAX_NESTS+1 links.
Currently, ep_loop_check_proc() ensures that the graph is loop-free and
does some recursion depth checks, but those recursion depth checks don't
limit the depth of the resulting tree for two reasons:
- They don't look upwards in the tree.
- If there are multiple downwards paths of different lengths, only one of
the paths is actually considered for the depth check since commit
28d82dc1c4ed ("epoll: limit paths").
Essentially, the current recursion depth check in ep_loop_check_proc() just
serves to prevent it from recursing too deeply while checking for loops.
A more thorough check is done in reverse_path_check() after the new graph
edge has already been created; this checks, among other things, that no
paths going upwards from any non-epoll file with a length of more than 5
edges exist. However, this check does not apply to non-epoll files.
As a result, it is possible to recurse to a depth of at least roughly 500,
tested on v6.15. (I am unsure if deeper recursion is possible; and this may
have changed with commit 8c44dac8add7 ("eventpoll: Fix priority inversion
problem").)
To fix it:
1. In ep_loop_check_proc(), note the subtree depth of each visited node,
and use subtree depths for the total depth calculation even when a subtree
has already been visited.
2. Add ep_get_upwards_depth_proc() for similarly determining the maximum
depth of an upwards walk.
3. In ep_loop_check(), use these values to limit the total path length
between epoll nodes to EP_MAX_NESTS edges.
CVSS Score
5.5
EPSS Score
0.0
Published
2025-08-19
In the Linux kernel, the following vulnerability has been resolved:
staging: fbtft: fix potential memory leak in fbtft_framebuffer_alloc()
In the error paths after fb_info structure is successfully allocated,
the memory allocated in fb_deferred_io_init() for info->pagerefs is not
freed. Fix that by adding the cleanup function on the error path.
CVSS Score
5.5
EPSS Score
0.0
Published
2025-08-19
In the Linux kernel, the following vulnerability has been resolved:
iwlwifi: Add missing check for alloc_ordered_workqueue
Add check for the return value of alloc_ordered_workqueue since it may
return NULL pointer.
CVSS Score
5.5
EPSS Score
0.0
Published
2025-08-19
In the Linux kernel, the following vulnerability has been resolved:
wifi: rtl818x: Kill URBs before clearing tx status queue
In rtl8187_stop() move the call of usb_kill_anchored_urbs() before clearing
b_tx_status.queue. This change prevents callbacks from using already freed
skb due to anchor was not killed before freeing such skb.
BUG: kernel NULL pointer dereference, address: 0000000000000080
#PF: supervisor read access in kernel mode
#PF: error_code(0x0000) - not-present page
PGD 0 P4D 0
Oops: Oops: 0000 [#1] SMP NOPTI
CPU: 7 UID: 0 PID: 0 Comm: swapper/7 Not tainted 6.15.0 #8 PREEMPT(voluntary)
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 0.0.0 02/06/2015
RIP: 0010:ieee80211_tx_status_irqsafe+0x21/0xc0 [mac80211]
Call Trace:
<IRQ>
rtl8187_tx_cb+0x116/0x150 [rtl8187]
__usb_hcd_giveback_urb+0x9d/0x120
usb_giveback_urb_bh+0xbb/0x140
process_one_work+0x19b/0x3c0
bh_worker+0x1a7/0x210
tasklet_action+0x10/0x30
handle_softirqs+0xf0/0x340
__irq_exit_rcu+0xcd/0xf0
common_interrupt+0x85/0xa0
</IRQ>
Tested on RTL8187BvE device.
Found by Linux Verification Center (linuxtesting.org) with SVACE.
CVSS Score
5.5
EPSS Score
0.0
Published
2025-08-19
In the Linux kernel, the following vulnerability has been resolved:
padata: Fix pd UAF once and for all
There is a race condition/UAF in padata_reorder that goes back
to the initial commit. A reference count is taken at the start
of the process in padata_do_parallel, and released at the end in
padata_serial_worker.
This reference count is (and only is) required for padata_replace
to function correctly. If padata_replace is never called then
there is no issue.
In the function padata_reorder which serves as the core of padata,
as soon as padata is added to queue->serial.list, and the associated
spin lock released, that padata may be processed and the reference
count on pd would go away.
Fix this by getting the next padata before the squeue->serial lock
is released.
In order to make this possible, simplify padata_reorder by only
calling it once the next padata arrives.
CVSS Score
7.8
EPSS Score
0.0
Published
2025-08-19
In the Linux kernel, the following vulnerability has been resolved:
ipv6: reject malicious packets in ipv6_gso_segment()
syzbot was able to craft a packet with very long IPv6 extension headers
leading to an overflow of skb->transport_header.
This 16bit field has a limited range.
Add skb_reset_transport_header_careful() helper and use it
from ipv6_gso_segment()
WARNING: CPU: 0 PID: 5871 at ./include/linux/skbuff.h:3032 skb_reset_transport_header include/linux/skbuff.h:3032 [inline]
WARNING: CPU: 0 PID: 5871 at ./include/linux/skbuff.h:3032 ipv6_gso_segment+0x15e2/0x21e0 net/ipv6/ip6_offload.c:151
Modules linked in:
CPU: 0 UID: 0 PID: 5871 Comm: syz-executor211 Not tainted 6.16.0-rc6-syzkaller-g7abc678e3084 #0 PREEMPT(full)
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/12/2025
RIP: 0010:skb_reset_transport_header include/linux/skbuff.h:3032 [inline]
RIP: 0010:ipv6_gso_segment+0x15e2/0x21e0 net/ipv6/ip6_offload.c:151
Call Trace:
<TASK>
skb_mac_gso_segment+0x31c/0x640 net/core/gso.c:53
nsh_gso_segment+0x54a/0xe10 net/nsh/nsh.c:110
skb_mac_gso_segment+0x31c/0x640 net/core/gso.c:53
__skb_gso_segment+0x342/0x510 net/core/gso.c:124
skb_gso_segment include/net/gso.h:83 [inline]
validate_xmit_skb+0x857/0x11b0 net/core/dev.c:3950
validate_xmit_skb_list+0x84/0x120 net/core/dev.c:4000
sch_direct_xmit+0xd3/0x4b0 net/sched/sch_generic.c:329
__dev_xmit_skb net/core/dev.c:4102 [inline]
__dev_queue_xmit+0x17b6/0x3a70 net/core/dev.c:4679
CVSS Score
7.8
EPSS Score
0.0
Published
2025-08-19
In the Linux kernel, the following vulnerability has been resolved:
pptp: ensure minimal skb length in pptp_xmit()
Commit aabc6596ffb3 ("net: ppp: Add bound checking for skb data
on ppp_sync_txmung") fixed ppp_sync_txmunge()
We need a similar fix in pptp_xmit(), otherwise we might
read uninit data as reported by syzbot.
BUG: KMSAN: uninit-value in pptp_xmit+0xc34/0x2720 drivers/net/ppp/pptp.c:193
pptp_xmit+0xc34/0x2720 drivers/net/ppp/pptp.c:193
ppp_channel_bridge_input drivers/net/ppp/ppp_generic.c:2290 [inline]
ppp_input+0x1d6/0xe60 drivers/net/ppp/ppp_generic.c:2314
pppoe_rcv_core+0x1e8/0x760 drivers/net/ppp/pppoe.c:379
sk_backlog_rcv+0x142/0x420 include/net/sock.h:1148
__release_sock+0x1d3/0x330 net/core/sock.c:3213
release_sock+0x6b/0x270 net/core/sock.c:3767
pppoe_sendmsg+0x15d/0xcb0 drivers/net/ppp/pppoe.c:904
sock_sendmsg_nosec net/socket.c:712 [inline]
__sock_sendmsg+0x330/0x3d0 net/socket.c:727
____sys_sendmsg+0x893/0xd80 net/socket.c:2566
___sys_sendmsg+0x271/0x3b0 net/socket.c:2620
__sys_sendmmsg+0x2d9/0x7c0 net/socket.c:2709
CVSS Score
7.8
EPSS Score
0.0
Published
2025-08-19
In the Linux kernel, the following vulnerability has been resolved:
powerpc/eeh: Make EEH driver device hotplug safe
Multiple race conditions existed between the PCIe hotplug driver and the
EEH driver, leading to a variety of kernel oopses of the same general
nature:
<pcie device unplug>
<eeh driver trigger>
<hotplug removal trigger>
<pcie tree reconfiguration>
<eeh recovery next step>
<oops in EEH driver bus iteration loop>
A second class of oops is also seen when the underlying bus disappears
during device recovery.
Refactor the EEH module to be PCI rescan and remove safe. Also clean
up a few minor formatting / readability issues.
CVSS Score
5.5
EPSS Score
0.0
Published
2025-08-19
In the Linux kernel, the following vulnerability has been resolved:
f2fs: fix to avoid panic in f2fs_evict_inode
As syzbot [1] reported as below:
R10: 0000000000000100 R11: 0000000000000206 R12: 00007ffe17473450
R13: 00007f28b1c10854 R14: 000000000000dae5 R15: 00007ffe17474520
</TASK>
---[ end trace 0000000000000000 ]---
==================================================================
BUG: KASAN: use-after-free in __list_del_entry_valid+0xa6/0x130 lib/list_debug.c:62
Read of size 8 at addr ffff88812d962278 by task syz-executor/564
CPU: 1 PID: 564 Comm: syz-executor Tainted: G W 6.1.129-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2025
Call Trace:
<TASK>
__dump_stack+0x21/0x24 lib/dump_stack.c:88
dump_stack_lvl+0xee/0x158 lib/dump_stack.c:106
print_address_description+0x71/0x210 mm/kasan/report.c:316
print_report+0x4a/0x60 mm/kasan/report.c:427
kasan_report+0x122/0x150 mm/kasan/report.c:531
__asan_report_load8_noabort+0x14/0x20 mm/kasan/report_generic.c:351
__list_del_entry_valid+0xa6/0x130 lib/list_debug.c:62
__list_del_entry include/linux/list.h:134 [inline]
list_del_init include/linux/list.h:206 [inline]
f2fs_inode_synced+0xf7/0x2e0 fs/f2fs/super.c:1531
f2fs_update_inode+0x74/0x1c40 fs/f2fs/inode.c:585
f2fs_update_inode_page+0x137/0x170 fs/f2fs/inode.c:703
f2fs_write_inode+0x4ec/0x770 fs/f2fs/inode.c:731
write_inode fs/fs-writeback.c:1460 [inline]
__writeback_single_inode+0x4a0/0xab0 fs/fs-writeback.c:1677
writeback_single_inode+0x221/0x8b0 fs/fs-writeback.c:1733
sync_inode_metadata+0xb6/0x110 fs/fs-writeback.c:2789
f2fs_sync_inode_meta+0x16d/0x2a0 fs/f2fs/checkpoint.c:1159
block_operations fs/f2fs/checkpoint.c:1269 [inline]
f2fs_write_checkpoint+0xca3/0x2100 fs/f2fs/checkpoint.c:1658
kill_f2fs_super+0x231/0x390 fs/f2fs/super.c:4668
deactivate_locked_super+0x98/0x100 fs/super.c:332
deactivate_super+0xaf/0xe0 fs/super.c:363
cleanup_mnt+0x45f/0x4e0 fs/namespace.c:1186
__cleanup_mnt+0x19/0x20 fs/namespace.c:1193
task_work_run+0x1c6/0x230 kernel/task_work.c:203
exit_task_work include/linux/task_work.h:39 [inline]
do_exit+0x9fb/0x2410 kernel/exit.c:871
do_group_exit+0x210/0x2d0 kernel/exit.c:1021
__do_sys_exit_group kernel/exit.c:1032 [inline]
__se_sys_exit_group kernel/exit.c:1030 [inline]
__x64_sys_exit_group+0x3f/0x40 kernel/exit.c:1030
x64_sys_call+0x7b4/0x9a0 arch/x86/include/generated/asm/syscalls_64.h:232
do_syscall_x64 arch/x86/entry/common.c:51 [inline]
do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:81
entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7f28b1b8e169
Code: Unable to access opcode bytes at 0x7f28b1b8e13f.
RSP: 002b:00007ffe174710a8 EFLAGS: 00000246 ORIG_RAX: 00000000000000e7
RAX: ffffffffffffffda RBX: 00007f28b1c10879 RCX: 00007f28b1b8e169
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000001
RBP: 0000000000000002 R08: 00007ffe1746ee47 R09: 00007ffe17472360
R10: 0000000000000009 R11: 0000000000000246 R12: 00007ffe17472360
R13: 00007f28b1c10854 R14: 000000000000dae5 R15: 00007ffe17474520
</TASK>
Allocated by task 569:
kasan_save_stack mm/kasan/common.c:45 [inline]
kasan_set_track+0x4b/0x70 mm/kasan/common.c:52
kasan_save_alloc_info+0x25/0x30 mm/kasan/generic.c:505
__kasan_slab_alloc+0x72/0x80 mm/kasan/common.c:328
kasan_slab_alloc include/linux/kasan.h:201 [inline]
slab_post_alloc_hook+0x4f/0x2c0 mm/slab.h:737
slab_alloc_node mm/slub.c:3398 [inline]
slab_alloc mm/slub.c:3406 [inline]
__kmem_cache_alloc_lru mm/slub.c:3413 [inline]
kmem_cache_alloc_lru+0x104/0x220 mm/slub.c:3429
alloc_inode_sb include/linux/fs.h:3245 [inline]
f2fs_alloc_inode+0x2d/0x340 fs/f2fs/super.c:1419
alloc_inode fs/inode.c:261 [inline]
iget_locked+0x186/0x880 fs/inode.c:1373
f2fs_iget+0x55/0x4c60 fs/f2fs/inode.c:483
f2fs_lookup+0x366/0xab0 fs/f2fs/namei.c:487
__lookup_slow+0x2a3/0x3d0 fs/namei.c:1690
lookup_slow+0x57/0x70 fs/namei.c:1707
walk_component+0x2e6/0x410 fs/namei
---truncated---
CVSS Score
5.5
EPSS Score
0.0
Published
2025-08-19
In the Linux kernel, the following vulnerability has been resolved:
f2fs: fix to avoid UAF in f2fs_sync_inode_meta()
syzbot reported an UAF issue as below: [1] [2]
[1] https://syzkaller.appspot.com/text?tag=CrashReport&x=16594c60580000
==================================================================
BUG: KASAN: use-after-free in __list_del_entry_valid+0xa6/0x130 lib/list_debug.c:62
Read of size 8 at addr ffff888100567dc8 by task kworker/u4:0/8
CPU: 1 PID: 8 Comm: kworker/u4:0 Tainted: G W 6.1.129-syzkaller-00017-g642656a36791 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2025
Workqueue: writeback wb_workfn (flush-7:0)
Call Trace:
<TASK>
__dump_stack lib/dump_stack.c:88 [inline]
dump_stack_lvl+0x151/0x1b7 lib/dump_stack.c:106
print_address_description mm/kasan/report.c:316 [inline]
print_report+0x158/0x4e0 mm/kasan/report.c:427
kasan_report+0x13c/0x170 mm/kasan/report.c:531
__asan_report_load8_noabort+0x14/0x20 mm/kasan/report_generic.c:351
__list_del_entry_valid+0xa6/0x130 lib/list_debug.c:62
__list_del_entry include/linux/list.h:134 [inline]
list_del_init include/linux/list.h:206 [inline]
f2fs_inode_synced+0x100/0x2e0 fs/f2fs/super.c:1553
f2fs_update_inode+0x72/0x1c40 fs/f2fs/inode.c:588
f2fs_update_inode_page+0x135/0x170 fs/f2fs/inode.c:706
f2fs_write_inode+0x416/0x790 fs/f2fs/inode.c:734
write_inode fs/fs-writeback.c:1460 [inline]
__writeback_single_inode+0x4cf/0xb80 fs/fs-writeback.c:1677
writeback_sb_inodes+0xb32/0x1910 fs/fs-writeback.c:1903
__writeback_inodes_wb+0x118/0x3f0 fs/fs-writeback.c:1974
wb_writeback+0x3da/0xa00 fs/fs-writeback.c:2081
wb_check_background_flush fs/fs-writeback.c:2151 [inline]
wb_do_writeback fs/fs-writeback.c:2239 [inline]
wb_workfn+0xbba/0x1030 fs/fs-writeback.c:2266
process_one_work+0x73d/0xcb0 kernel/workqueue.c:2299
worker_thread+0xa60/0x1260 kernel/workqueue.c:2446
kthread+0x26d/0x300 kernel/kthread.c:386
ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295
</TASK>
Allocated by task 298:
kasan_save_stack mm/kasan/common.c:45 [inline]
kasan_set_track+0x4b/0x70 mm/kasan/common.c:52
kasan_save_alloc_info+0x1f/0x30 mm/kasan/generic.c:505
__kasan_slab_alloc+0x6c/0x80 mm/kasan/common.c:333
kasan_slab_alloc include/linux/kasan.h:202 [inline]
slab_post_alloc_hook+0x53/0x2c0 mm/slab.h:768
slab_alloc_node mm/slub.c:3421 [inline]
slab_alloc mm/slub.c:3431 [inline]
__kmem_cache_alloc_lru mm/slub.c:3438 [inline]
kmem_cache_alloc_lru+0x102/0x270 mm/slub.c:3454
alloc_inode_sb include/linux/fs.h:3255 [inline]
f2fs_alloc_inode+0x2d/0x350 fs/f2fs/super.c:1437
alloc_inode fs/inode.c:261 [inline]
iget_locked+0x18c/0x7e0 fs/inode.c:1373
f2fs_iget+0x55/0x4ca0 fs/f2fs/inode.c:486
f2fs_lookup+0x3c1/0xb50 fs/f2fs/namei.c:484
__lookup_slow+0x2b9/0x3e0 fs/namei.c:1689
lookup_slow+0x5a/0x80 fs/namei.c:1706
walk_component+0x2e7/0x410 fs/namei.c:1997
lookup_last fs/namei.c:2454 [inline]
path_lookupat+0x16d/0x450 fs/namei.c:2478
filename_lookup+0x251/0x600 fs/namei.c:2507
vfs_statx+0x107/0x4b0 fs/stat.c:229
vfs_fstatat fs/stat.c:267 [inline]
vfs_lstat include/linux/fs.h:3434 [inline]
__do_sys_newlstat fs/stat.c:423 [inline]
__se_sys_newlstat+0xda/0x7c0 fs/stat.c:417
__x64_sys_newlstat+0x5b/0x70 fs/stat.c:417
x64_sys_call+0x52/0x9a0 arch/x86/include/generated/asm/syscalls_64.h:7
do_syscall_x64 arch/x86/entry/common.c:51 [inline]
do_syscall_64+0x3b/0x80 arch/x86/entry/common.c:81
entry_SYSCALL_64_after_hwframe+0x68/0xd2
Freed by task 0:
kasan_save_stack mm/kasan/common.c:45 [inline]
kasan_set_track+0x4b/0x70 mm/kasan/common.c:52
kasan_save_free_info+0x2b/0x40 mm/kasan/generic.c:516
____kasan_slab_free+0x131/0x180 mm/kasan/common.c:241
__kasan_slab_free+0x11/0x20 mm/kasan/common.c:249
kasan_slab_free include/linux/kasan.h:178 [inline]
slab_free_hook mm/slub.c:1745 [inline]
slab_free_freelist_hook mm/slub.c:1771 [inline]
slab_free mm/slub.c:3686 [inline]
kmem_cache_free+0x
---truncated---
CVSS Score
5.5
EPSS Score
0.0
Published
2025-08-19