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NULL Pointer Dereference Affecting kernel-uek package, versions <0:5.4.17-2136.337.5.el7uek

Severity

 Recommended
high

Based on Oracle Linux security rating.

Threat Intelligence

EPSS
0.04% (6th percentile)

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  • Snyk IDSNYK-ORACLE7-KERNELUEK-8370861
  • published14 Nov 2024
  • disclosed21 Oct 2024
Report a new vulnerability Found a mistake?

Introduced: 21 Oct 2024

CVE-2024-49863  (opens in a new tab)
CWE-476  (opens in a new tab)

How to fix?

Upgrade Oracle:7 kernel-uek to version 0:5.4.17-2136.337.5.el7uek or higher.
This issue was patched in ELSA-2024-12813.

NVD Description

Note: Versions mentioned in the description apply only to the upstream kernel-uek package and not the kernel-uek package as distributed by Oracle. See How to fix? for Oracle:7 relevant fixed versions and status.

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

vhost/scsi: null-ptr-dereference in vhost_scsi_get_req()

Since commit 3f8ca2e115e5 ("vhost/scsi: Extract common handling code from control queue handler") a null pointer dereference bug can be triggered when guest sends an SCSI AN request.

In vhost_scsi_ctl_handle_vq(), vc.target is assigned with &amp;v_req.tmf.lun[1] within a switch-case block and is then passed to vhost_scsi_get_req() which extracts vc-&gt;req and tpg. However, for a VIRTIO_SCSI_T_AN_* request, tpg is not required, so vc.target is set to NULL in this branch. Later, in vhost_scsi_get_req(), vc-&gt;target is dereferenced without being checked, leading to a null pointer dereference bug. This bug can be triggered from guest.

When this bug occurs, the vhost_worker process is killed while holding vq-&gt;mutex and the corresponding tpg will remain occupied indefinitely.

Below is the KASAN report: Oops: general protection fault, probably for non-canonical address 0xdffffc0000000000: 0000 [#1] PREEMPT SMP KASAN NOPTI KASAN: null-ptr-deref in range [0x0000000000000000-0x0000000000000007] CPU: 1 PID: 840 Comm: poc Not tainted 6.10.0+ #1 Hardware name: QEMU Ubuntu 24.04 PC (i440FX + PIIX, 1996), BIOS 1.16.3-debian-1.16.3-2 04/01/2014 RIP: 0010:vhost_scsi_get_req+0x165/0x3a0 Code: 00 fc ff df 48 89 fa 48 c1 ea 03 80 3c 02 00 0f 85 2b 02 00 00 48 b8 00 00 00 00 00 fc ff df 4d 8b 65 30 4c 89 e2 48 c1 ea 03 <0f> b6 04 02 4c 89 e2 83 e2 07 38 d0 7f 08 84 c0 0f 85 be 01 00 00 RSP: 0018:ffff888017affb50 EFLAGS: 00010246 RAX: dffffc0000000000 RBX: ffff88801b000000 RCX: 0000000000000000 RDX: 0000000000000000 RSI: 0000000000000000 RDI: ffff888017affcb8 RBP: ffff888017affb80 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000000 R13: ffff888017affc88 R14: ffff888017affd1c R15: ffff888017993000 FS: 000055556e076500(0000) GS:ffff88806b100000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00000000200027c0 CR3: 0000000010ed0004 CR4: 0000000000370ef0 Call Trace: <TASK> ? show_regs+0x86/0xa0 ? die_addr+0x4b/0xd0 ? exc_general_protection+0x163/0x260 ? asm_exc_general_protection+0x27/0x30 ? vhost_scsi_get_req+0x165/0x3a0 vhost_scsi_ctl_handle_vq+0x2a4/0xca0 ? __pfx_vhost_scsi_ctl_handle_vq+0x10/0x10 ? __switch_to+0x721/0xeb0 ? __schedule+0xda5/0x5710 ? __kasan_check_write+0x14/0x30 ? _raw_spin_lock+0x82/0xf0 vhost_scsi_ctl_handle_kick+0x52/0x90 vhost_run_work_list+0x134/0x1b0 vhost_task_fn+0x121/0x350 ... </TASK> ---[ end trace 0000000000000000 ]---

Let's add a check in vhost_scsi_get_req.

[whitespace fixes]

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