Linux: >> Linux Kernel >> 4.9.0 Security Vulnerabilities
In the Linux kernel, the following vulnerability has been resolved:
perf: Fix __perf_event_overflow() vs perf_remove_from_context() race
Make sure that __perf_event_overflow() runs with IRQs disabled for all
possible callchains. Specifically the software events can end up running
it with only preemption disabled.
This opens up a race vs perf_event_exit_event() and friends that will go
and free various things the overflow path expects to be present, like
the BPF program.
CVSS Score
7.8
EPSS Score
0.0
Published
2026-03-20
In the Linux kernel, the following vulnerability has been resolved:
f2fs: fix to do sanity check on node footer in {read,write}_end_io
-----------[ cut here ]------------
kernel BUG at fs/f2fs/data.c:358!
Call Trace:
<IRQ>
blk_update_request+0x5eb/0xe70 block/blk-mq.c:987
blk_mq_end_request+0x3e/0x70 block/blk-mq.c:1149
blk_complete_reqs block/blk-mq.c:1224 [inline]
blk_done_softirq+0x107/0x160 block/blk-mq.c:1229
handle_softirqs+0x283/0x870 kernel/softirq.c:579
__do_softirq kernel/softirq.c:613 [inline]
invoke_softirq kernel/softirq.c:453 [inline]
__irq_exit_rcu+0xca/0x1f0 kernel/softirq.c:680
irq_exit_rcu+0x9/0x30 kernel/softirq.c:696
instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1050 [inline]
sysvec_apic_timer_interrupt+0xa6/0xc0 arch/x86/kernel/apic/apic.c:1050
</IRQ>
In f2fs_write_end_io(), it detects there is inconsistency in between
node page index (nid) and footer.nid of node page.
If footer of node page is corrupted in fuzzed image, then we load corrupted
node page w/ async method, e.g. f2fs_ra_node_pages() or f2fs_ra_node_page(),
in where we won't do sanity check on node footer, once node page becomes
dirty, we will encounter this bug after node page writeback.
CVSS Score
5.5
EPSS Score
0.0
Published
2026-03-18
In the Linux kernel, the following vulnerability has been resolved:
fbdev: rivafb: fix divide error in nv3_arb()
A userspace program can trigger the RIVA NV3 arbitration code by calling
the FBIOPUT_VSCREENINFO ioctl on /dev/fb*. When doing so, the driver
recomputes FIFO arbitration parameters in nv3_arb(), using state->mclk_khz
(derived from the PRAMDAC MCLK PLL) as a divisor without validating it
first.
In a normal setup, state->mclk_khz is provided by the real hardware and is
non-zero. However, an attacker can construct a malicious or misconfigured
device (e.g. a crafted/emulated PCI device) that exposes a bogus PLL
configuration, causing state->mclk_khz to become zero. Once
nv3_get_param() calls nv3_arb(), the division by state->mclk_khz in the gns
calculation causes a divide error and crashes the kernel.
Fix this by checking whether state->mclk_khz is zero and bailing out before
doing the division.
The following log reveals it:
rivafb: setting virtual Y resolution to 2184
divide error: 0000 [#1] PREEMPT SMP KASAN PTI
CPU: 0 PID: 2187 Comm: syz-executor.0 Not tainted 5.18.0-rc1+ #1
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.12.0-59-gc9ba5276e321-prebuilt.qemu.org 04/01/2014
RIP: 0010:nv3_arb drivers/video/fbdev/riva/riva_hw.c:439 [inline]
RIP: 0010:nv3_get_param+0x3ab/0x13b0 drivers/video/fbdev/riva/riva_hw.c:546
Call Trace:
nv3CalcArbitration.constprop.0+0x255/0x460 drivers/video/fbdev/riva/riva_hw.c:603
nv3UpdateArbitrationSettings drivers/video/fbdev/riva/riva_hw.c:637 [inline]
CalcStateExt+0x447/0x1b90 drivers/video/fbdev/riva/riva_hw.c:1246
riva_load_video_mode+0x8a9/0xea0 drivers/video/fbdev/riva/fbdev.c:779
rivafb_set_par+0xc0/0x5f0 drivers/video/fbdev/riva/fbdev.c:1196
fb_set_var+0x604/0xeb0 drivers/video/fbdev/core/fbmem.c:1033
do_fb_ioctl+0x234/0x670 drivers/video/fbdev/core/fbmem.c:1109
fb_ioctl+0xdd/0x130 drivers/video/fbdev/core/fbmem.c:1188
__x64_sys_ioctl+0x122/0x190 fs/ioctl.c:856
CVSS Score
5.5
EPSS Score
0.0
Published
2026-03-18
In the Linux kernel, the following vulnerability has been resolved:
f2fs: fix IS_CHECKPOINTED flag inconsistency issue caused by concurrent atomic commit and checkpoint writes
During SPO tests, when mounting F2FS, an -EINVAL error was returned from
f2fs_recover_inode_page. The issue occurred under the following scenario
Thread A Thread B
f2fs_ioc_commit_atomic_write
- f2fs_do_sync_file // atomic = true
- f2fs_fsync_node_pages
: last_folio = inode folio
: schedule before folio_lock(last_folio) f2fs_write_checkpoint
- block_operations// writeback last_folio
- schedule before f2fs_flush_nat_entries
: set_fsync_mark(last_folio, 1)
: set_dentry_mark(last_folio, 1)
: folio_mark_dirty(last_folio)
- __write_node_folio(last_folio)
: f2fs_down_read(&sbi->node_write)//block
- f2fs_flush_nat_entries
: {struct nat_entry}->flag |= BIT(IS_CHECKPOINTED)
- unblock_operations
: f2fs_up_write(&sbi->node_write)
f2fs_write_checkpoint//return
: f2fs_do_write_node_page()
f2fs_ioc_commit_atomic_write//return
SPO
Thread A calls f2fs_need_dentry_mark(sbi, ino), and the last_folio has
already been written once. However, the {struct nat_entry}->flag did not
have the IS_CHECKPOINTED set, causing set_dentry_mark(last_folio, 1) and
write last_folio again after Thread B finishes f2fs_write_checkpoint.
After SPO and reboot, it was detected that {struct node_info}->blk_addr
was not NULL_ADDR because Thread B successfully write the checkpoint.
This issue only occurs in atomic write scenarios. For regular file
fsync operations, the folio must be dirty. If
block_operations->f2fs_sync_node_pages successfully submit the folio
write, this path will not be executed. Otherwise, the
f2fs_write_checkpoint will need to wait for the folio write submission
to complete, as sbi->nr_pages[F2FS_DIRTY_NODES] > 0. Therefore, the
situation where f2fs_need_dentry_mark checks that the {struct
nat_entry}->flag /wo the IS_CHECKPOINTED flag, but the folio write has
already been submitted, will not occur.
Therefore, for atomic file fsync, sbi->node_write should be acquired
through __write_node_folio to ensure that the IS_CHECKPOINTED flag
correctly indicates that the checkpoint write has been completed.
CVSS Score
5.5
EPSS Score
0.0
Published
2026-03-18
In the Linux kernel, the following vulnerability has been resolved:
apparmor: validate DFA start states are in bounds in unpack_pdb
Start states are read from untrusted data and used as indexes into the
DFA state tables. The aa_dfa_next() function call in unpack_pdb() will
access dfa->tables[YYTD_ID_BASE][start], and if the start state exceeds
the number of states in the DFA, this results in an out-of-bound read.
==================================================================
BUG: KASAN: slab-out-of-bounds in aa_dfa_next+0x2a1/0x360
Read of size 4 at addr ffff88811956fb90 by task su/1097
...
Reject policies with out-of-bounds start states during unpacking
to prevent the issue.
CVSS Score
7.1
EPSS Score
0.0
Published
2026-03-18
In the Linux kernel, the following vulnerability has been resolved:
media: dvb-core: fix wrong reinitialization of ringbuffer on reopen
dvb_dvr_open() calls dvb_ringbuffer_init() when a new reader opens the
DVR device. dvb_ringbuffer_init() calls init_waitqueue_head(), which
reinitializes the waitqueue list head to empty.
Since dmxdev->dvr_buffer.queue is a shared waitqueue (all opens of the
same DVR device share it), this orphans any existing waitqueue entries
from io_uring poll or epoll, leaving them with stale prev/next pointers
while the list head is reset to {self, self}.
The waitqueue and spinlock in dvr_buffer are already properly
initialized once in dvb_dmxdev_init(). The open path only needs to
reset the buffer data pointer, size, and read/write positions.
Replace the dvb_ringbuffer_init() call in dvb_dvr_open() with direct
assignment of data/size and a call to dvb_ringbuffer_reset(), which
properly resets pread, pwrite, and error with correct memory ordering
without touching the waitqueue or spinlock.
CVSS Score
7.8
EPSS Score
0.0
Published
2026-03-18
In the Linux kernel, the following vulnerability has been resolved:
net: add proper RCU protection to /proc/net/ptype
Yin Fengwei reported an RCU stall in ptype_seq_show() and provided
a patch.
Real issue is that ptype_seq_next() and ptype_seq_show() violate
RCU rules.
ptype_seq_show() runs under rcu_read_lock(), and reads pt->dev
to get device name without any barrier.
At the same time, concurrent writers can remove a packet_type structure
(which is correctly freed after an RCU grace period) and clear pt->dev
without an RCU grace period.
Define ptype_iter_state to carry a dev pointer along seq_net_private:
struct ptype_iter_state {
struct seq_net_private p;
struct net_device *dev; // added in this patch
};
We need to record the device pointer in ptype_get_idx() and
ptype_seq_next() so that ptype_seq_show() is safe against
concurrent pt->dev changes.
We also need to add full RCU protection in ptype_seq_next().
(Missing READ_ONCE() when reading list.next values)
Many thanks to Dong Chenchen for providing a repro.
CVSS Score
5.5
EPSS Score
0.0
Published
2026-03-18
In the Linux kernel, the following vulnerability has been resolved:
net: liquidio: Fix off-by-one error in PF setup_nic_devices() cleanup
In setup_nic_devices(), the initialization loop jumps to the label
setup_nic_dev_free on failure. The current cleanup loop while(i--)
skip the failing index i, causing a memory leak.
Fix this by changing the loop to iterate from the current index i
down to 0.
Also, decrement i in the devlink_alloc failure path to point to the
last successfully allocated index.
Compile tested only. Issue found using code review.
CVSS Score
5.5
EPSS Score
0.0
Published
2026-03-18
In the Linux kernel, the following vulnerability has been resolved:
btrfs: do not free data reservation in fallback from inline due to -ENOSPC
If we fail to create an inline extent due to -ENOSPC, we will attempt to
go through the normal COW path, reserve an extent, create an ordered
extent, etc. However we were always freeing the reserved qgroup data,
which is wrong since we will use data. Fix this by freeing the reserved
qgroup data in __cow_file_range_inline() only if we are not doing the
fallback (ret is <= 0).
CVSS Score
5.5
EPSS Score
0.0
Published
2026-03-18
In the Linux kernel, the following vulnerability has been resolved:
btrfs: fix reservation leak in some error paths when inserting inline extent
If we fail to allocate a path or join a transaction, we return from
__cow_file_range_inline() without freeing the reserved qgroup data,
resulting in a leak. Fix this by ensuring we call btrfs_qgroup_free_data()
in such cases.
CVSS Score
5.5
EPSS Score
0.0
Published
2026-03-18