CVE-2024-42304

ext4: make sure the first directory block is not a hole

7.8 HighFix available

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

ext4: make sure the first directory block is not a hole

The syzbot constructs a directory that has no dirblock but is non-inline, i.e. the first directory block is a hole. And no errors are reported when creating files in this directory in the following flow.

ext4_mknod
 ...
  ext4_add_entry
    // Read block 0
    ext4_read_dirblock(dir, block, DIRENT)
      bh = ext4_bread(NULL, inode, block, 0)
      if (!bh && (type == INDEX || type == DIRENT_HTREE))
      // The first directory block is a hole
      // But type == DIRENT, so no error is reported.

After that, we get a directory block without '.' and '..' but with a valid dentry. This may cause some code that relies on dot or dotdot (such as make_indexed_dir()) to crash.

Therefore when ext4_read_dirblock() finds that the first directory block is a hole report that the filesystem is corrupted and return an error to avoid loading corrupted data from disk causing something bad.

Attack profile

How easy it is to exploit

Attack vector: Local
Complexity: Low
Privileges needed: Low
User interaction: None

What an attacker can affect

Confidentiality: High
Integrity: High
Availability: High

Exploit likelihood

0.23%Up 0.2 points since Aug 18, 2024

What each source reports

CVE List Score used 7.8

ext4: make sure the first directory block is not a hole

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

ext4: make sure the first directory block is not a hole

ext4_mknod
 ...
  ext4_add_entry
    // Read block 0
    ext4_read_dirblock(dir, block, DIRENT)
      bh = ext4_bread(NULL, inode, block, 0)
      if (!bh && (type == INDEX || type == DIRENT_HTREE))
      // The first directory block is a hole
      // But type == DIRENT, so no error is reported.

After that, we get a directory block without '.' and '..' but with a valid dentry. This may cause some code that relies on dot or dotdot (such as make_indexed_dir()) to crash.

Record: CVE-2024-42304
CVSS 3.1: 7.8 HighCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Updated: 2026-11-02

EUVDEUVD-2024-39527 7.8

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

ext4: make sure the first directory block is not a hole

ext4_mknod
 ...
  ext4_add_entry
    // Read block 0
    ext4_read_dirblock(dir, block, DIRENT)
      bh = ext4_bread(NULL, inode, block, 0)
      if (!bh && (type == INDEX || type == DIRENT_HTREE))
      // The first directory block is a hole
      // But type == DIRENT, so no error is reported.

After that, we get a directory block without '.' and '..' but with a valid dentry. This may cause some code that relies on dot or dotdot (such as make_indexed_dir()) to crash.

Record: EUVD-2024-39527
CVSS 3.1: 7.8 HighCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Updated: 2026-11-02

GitHub AdvisoriesGHSA-v546-2fcj-rwvx 5.5

In the Linux kernel, the following vulnerability has been resolved: ext4: make sure the first...

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

ext4: make sure the first directory block is not a hole

ext4_mknod
 ...
  ext4_add_entry
    // Read block 0
    ext4_read_dirblock(dir, block, DIRENT)
      bh = ext4_bread(NULL, inode, block, 0)
      if (!bh && (type == INDEX || type == DIRENT_HTREE))
      // The first directory block is a hole
      // But type == DIRENT, so no error is reported.

After that, we get a directory block without '.' and '..' but with a valid dentry. This may cause some code that relies on dot or dotdot (such as make_indexed_dir()) to crash.

Record: GHSA-v546-2fcj-rwvx
CVSS 3.1: 5.5 MediumCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
Updated: 2026-11-02

NVD 7.8

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

ext4: make sure the first directory block is not a hole

ext4_mknod
 ...
  ext4_add_entry
    // Read block 0
    ext4_read_dirblock(dir, block, DIRENT)
      bh = ext4_bread(NULL, inode, block, 0)
      if (!bh && (type == INDEX || type == DIRENT_HTREE))
      // The first directory block is a hole
      // But type == DIRENT, so no error is reported.

After that, we get a directory block without '.' and '..' but with a valid dentry. This may cause some code that relies on dot or dotdot (such as make_indexed_dir()) to crash.

Record: CVE-2024-42304
CVSS 3.1: 7.8 HighCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
CVSS 3.1: 5.5 MediumCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
Updated: 2026-11-02

OSVBELL-CVE-2024-42304 5.5

Record: BELL-CVE-2024-42304
CVSS 3.1: 5.5 MediumCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
Updated: 2026-11-02

OSV 7.8

ext4: make sure the first directory block is not a hole

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

ext4: make sure the first directory block is not a hole

ext4_mknod
 ...
  ext4_add_entry
    // Read block 0
    ext4_read_dirblock(dir, block, DIRENT)
      bh = ext4_bread(NULL, inode, block, 0)
      if (!bh && (type == INDEX || type == DIRENT_HTREE))
      // The first directory block is a hole
      // But type == DIRENT, so no error is reported.

After that, we get a directory block without '.' and '..' but with a valid dentry. This may cause some code that relies on dot or dotdot (such as make_indexed_dir()) to crash.

Record: CVE-2024-42304
CVSS 3.1: 7.8 HighCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Updated: 2026-11-02

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OSVDEBIAN-CVE-2024-42304 5.5

In the Linux kernel, the following vulnerability has been resolved: ext4: make sure the first directory block is not a hole The syzbot constructs a directory that has no dirblock but is non-inline, i.e. the first directory block is a hole. And no errors are reported when creating files in this directory in the following flow. ext4_mknod ... ext4_add_entry // Read block 0 ext4_read_dirblock(dir, block, DIRENT) bh = ext4_bread(NULL, inode, block, 0) if (!bh && (type == INDEX || type == DIRENT_HTREE)) // The first directory block is a hole // But type == DIRENT, so no error is reported. After that, we get a directory block without '.' and '..' but with a valid dentry. This may cause some code that relies on dot or dotdot (such as make_indexed_dir()) to crash. Therefore when ext4_read_dirblock() finds that the first directory block is a hole report that the filesystem is corrupted and return an error to avoid loading corrupted data from disk causing something bad.

Record: DEBIAN-CVE-2024-42304
CVSS 3.1: 5.5 MediumCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
Updated: 2026-11-02

OSVOESA-2024-2028 7.8

kernel security update

The Linux Kernel, the operating system core itself.

Security Fix(es):

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

ipvlan: Dont Use skb->sk in ipvlan_process_v{4,6}_outbound

Raw packet from PF_PACKET socket ontop of an IPv6-backed ipvlan device will hit WARN_ON_ONCE() in sk_mc_loop() through sch_direct_xmit() path.

WARNING: CPU: 2 PID: 0 at net/core/sock.c:775 sk_mc_loop+0x2d/0x70 Modules linked in: sch_netem ipvlan rfkill cirrus drm_shmem_helper sg drm_kms_helper CPU: 2 PID: 0 Comm: swapper/2 Kdump: loaded Not tainted 6.9.0+ #279 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.15.0-1 04/01/2014 RIP: 0010:sk_mc_loop+0x2d/0x70 Code: fa 0f 1f 44 00 00 65 0f b7 15 f7 96 a3 4f 31 c0 66 85 d2 75 26 48 85 ff 74 1c RSP: 0018:ffffa9584015cd78 EFLAGS: 00010212 RAX: 0000000000000011 RBX: ffff91e585793e00 RCX: 0000000002c6a001 RDX: 0000000000000000 RSI: 0000000000000040 RDI: ffff91e589c0f000 RBP: ffff91e5855bd100 R08: 0000000000000000 R09: 3d00545216f43d00 R10: ffff91e584fdcc50 R11: 00000060dd8616f4 R12: ffff91e58132d000 R13: ffff91e584fdcc68 R14: ffff91e5869ce800 R15: ffff91e589c0f000 FS: 0000000000000000(0000) GS:ffff91e898100000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007f788f7c44c0 CR3: 0000000008e1a000 CR4: 00000000000006f0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: <IRQ> ? __warn (kernel/panic.c:693) ? sk_mc_loop (net/core/sock.c:760) ? report_bug (lib/bug.c:201 lib/bug.c:219) ? handle_bug (arch/x86/kernel/traps.c:239) ? exc_invalid_op (arch/x86/kernel/traps.c:260 (discriminator 1)) ? asm_exc_invalid_op (./arch/x86/include/asm/idtentry.h:621) ? sk_mc_loop (net/core/sock.c:760) ip6_finish_output2 (net/ipv6/ip6_output.c:83 (discriminator 1)) ? nf_hook_slow (net/netfilter/core.c:626) ip6_finish_output (net/ipv6/ip6_output.c:222) ? __pfx_ip6_finish_output (net/ipv6/ip6_output.c:215) ipvlan_xmit_mode_l3 (drivers/net/ipvlan/ipvlan_core.c:602) ipvlan ipvlan_start_xmit (drivers/net/ipvlan/ipvlan_main.c:226) ipvlan dev_hard_start_xmit (net/core/dev.c:3594) sch_direct_xmit (net/sched/sch_generic.c:343) __qdisc_run (net/sched/sch_generic.c:416) net_tx_action (net/core/dev.c:5286) handle_softirqs (kernel/softirq.c:555) __irq_exit_rcu (kernel/softirq.c:589) sysvec_apic_timer_interrupt (arch/x86/kernel/apic/apic.c:1043)

The warning triggers as this: packet_sendmsg packet_snd //skb->sk is packet sk __dev_queue_xmit __dev_xmit_skb //q->enqueue is not NULL __qdisc_run sch_direct_xmit dev_hard_start_xmit ipvlan_start_xmit ipvlan_xmit_mode_l3 //l3 mode ipvlan_process_outbound //vepa flag ipvlan_process_v6_outbound ip6_local_out __ip6_finish_output ip6_finish_output2 //multicast packet sk_mc_loop //sk->sk_family is AF_PACKET

Call ip{6}_local_out() with NULL sk in ipvlan as other tunnels to fix this.(CVE-2024-33621)

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

dma-mapping: benchmark: fix node id validation

While validating node ids in map_benchmark_ioctl(), node_possible() may be provided with invalid argument outside of [0,MAX_NUMNODES-1] range leading to:

BUG: KASAN: wild-memory-access in map_benchmark_ioctl (kernel/dma/map_benchmark.c:214) Read of size 8 at addr 1fffffff8ccb6398 by task dma_map_benchma/971 CPU: 7 PID: 971 Comm: dma_map_benchma Not tainted 6.9.0-rc6 #37 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996) Call Trace: <TASK> dump_stack_lvl (lib/dump_stack.c:117) kasan_report (mm/kasan/report.c:603) kasan_check_range (mm/kasan/generic.c:189) variable_test_bit…

Record: OESA-2024-2028
CVSS 3.1: 7.8 HighCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Updated: 2026-11-02

OSVOESA-2024-2029 7.8

kernel security update

The Linux Kernel, the operating system core itself.

Security Fix(es):

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

mlxsw: spectrum_acl_tcam: Fix stack corruption

When tc filters are first added to a net device, the corresponding local port gets bound to an ACL group in the device. The group contains a list of ACLs. In turn, each ACL points to a different TCAM region where the filters are stored. During forwarding, the ACLs are sequentially evaluated until a match is found.

One reason to place filters in different regions is when they are added with decreasing priorities and in an alternating order so that two consecutive filters can never fit in the same region because of their key usage.

In Spectrum-2 and newer ASICs the firmware started to report that the maximum number of ACLs in a group is more than 16, but the layout of the register that configures ACL groups (PAGT) was not updated to account for that. It is therefore possible to hit stack corruption [1] in the rare case where more than 16 ACLs in a group are required.

Fix by limiting the maximum ACL group size to the minimum between what the firmware reports and the maximum ACLs that fit in the PAGT register.

Add a test case to make sure the machine does not crash when this condition is hit.

[1] Kernel panic - not syncing: stack-protector: Kernel stack is corrupted in: mlxsw_sp_acl_tcam_group_update+0x116/0x120 [...] dump_stack_lvl+0x36/0x50 panic+0x305/0x330 __stack_chk_fail+0x15/0x20 mlxsw_sp_acl_tcam_group_update+0x116/0x120 mlxsw_sp_acl_tcam_group_region_attach+0x69/0x110 mlxsw_sp_acl_tcam_vchunk_get+0x492/0xa20 mlxsw_sp_acl_tcam_ventry_add+0x25/0xe0 mlxsw_sp_acl_rule_add+0x47/0x240 mlxsw_sp_flower_replace+0x1a9/0x1d0 tc_setup_cb_add+0xdc/0x1c0 fl_hw_replace_filter+0x146/0x1f0 fl_change+0xc17/0x1360 tc_new_tfilter+0x472/0xb90 rtnetlink_rcv_msg+0x313/0x3b0 netlink_rcv_skb+0x58/0x100 netlink_unicast+0x244/0x390 netlink_sendmsg+0x1e4/0x440 ____sys_sendmsg+0x164/0x260 ___sys_sendmsg+0x9a/0xe0 __sys_sendmsg+0x7a/0xc0 do_syscall_64+0x40/0xe0 entry_SYSCALL_64_after_hwframe+0x63/0x6b(CVE-2024-26586)

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

KVM: arm64: vgic-its: Avoid potential UAF in LPI translation cache

There is a potential UAF scenario in the case of an LPI translation cache hit racing with an operation that invalidates the cache, such as a DISCARD ITS command. The root of the problem is that vgic_its_check_cache() does not elevate the refcount on the vgic_irq before dropping the lock that serializes refcount changes.

Have vgic_its_check_cache() raise the refcount on the returned vgic_irq and add the corresponding decrement after queueing the interrupt.(CVE-2024-26598)

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

sched/membarrier: reduce the ability to hammer on sys_membarrier

On some systems, sys_membarrier can be very expensive, causing overall slowdowns for everything. So put a lock on the path in order to serialize the accesses to prevent the ability for this to be called at too high of a frequency and saturate the machine.(CVE-2024-26602)

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

tun: limit printing rate when illegal packet received by tun dev

vhost_worker will call tun call backs to receive packets. If too many illegal packets arrives, tun_do_read will keep dumping packet contents. When console is enabled, it will costs much more cpu time to dump packet and soft lockup will be detected.

net_ratelimit mechanism can be used to limit the dumping rate.

PID: 33036 TASK: ffff949da6f20000 CPU: 23 COMMAND: "vhost-32980" #0 [fffffe00003fce50] crash_nmi_callback at ffffffff89249253 #1 [fffffe00003fce58] nmi_handle at ffffffff89225fa3 #2 [fffffe00003fceb0] default_do_nmi at ffffffff8922642e #3 [fffffe00003fced0] do_nmi at ffffffff8922660d #4 [fffffe00003fcef0]…

Record: OESA-2024-2029
CVSS 3.1: 7.8 HighCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Updated: 2026-11-02

OSVOESA-2024-2030 7.8

kernel security update

The Linux Kernel, the operating system core itself.

Security Fix(es):

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

ALSA: gus: fix null pointer dereference on pointer block

The pointer block return from snd_gf1_dma_next_block could be null, so there is a potential null pointer dereference issue. Fix this by adding a null check before dereference.(CVE-2021-47207)