CVE-2025-21673: smb: client: fix double free of TCP_Server_Info::hostname

Published Jan 31, 2025
·
Updated

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

smb: client: fix double free of TCPServerInfo::hostname

When shutting down the server in cifsputtcpsession(), cifsd thread might be reconnecting to multiple DFS targets before it realizes it should exit the loop, so @server->hostname can't be freed as long as cifsd thread isn't done. Otherwise the following can happen:

RIP: 0010:slabfree+0x223/0x3c0 Code: 5e 41 5f c3 cc cc cc cc 4c 89 de 4c 89 cf 44 89 44 24 08 4c 89 1c 24 e8 fb cf 8e 00 44 8b 44 24 08 4c 8b 1c 24 e9 5f fe ff ff <0f> 0b 41 f7 45 08 00 0d 21 00 0f 85 2d ff ff ff e9 1f ff ff ff 80 RSP: 0018:ffffb26180dbfd08 EFLAGS: 00010246 RAX: ffff8ea34728e510 RBX: ffff8ea34728e500 RCX: 0000000000800068 RDX: 0000000000800068 RSI: 0000000000000000 RDI: ffff8ea340042400 RBP: ffffe112041ca380 R08: 0000000000000001 R09: 0000000000000000 R10: 6170732e31303000 R11: 70726f632e786563 R12: ffff8ea34728e500 R13: ffff8ea340042400 R14: ffff8ea34728e500 R15: 0000000000800068 FS: 0000000000000000(0000) GS:ffff8ea66fd80000(0000) 000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007ffc25376080 CR3: 000000012a2ba001 CR4: PKRU: 55555554 Call Trace: <TASK> ? showtraceloglvl+0x1c4/0x2df ? showtraceloglvl+0x1c4/0x2df ? reconnecttargetunlocked+0x3e/0x160 [cifs] ? diebody.cold+0x8/0xd ? die+0x2b/0x50 ? dotrap+0xce/0x120 ? slabfree+0x223/0x3c0 ? doerrortrap+0x65/0x80 ? slabfree+0x223/0x3c0 ? excinvalidop+0x4e/0x70 ? slabfree+0x223/0x3c0 ? asmexcinvalidop+0x16/0x20 ? slabfree+0x223/0x3c0 ? extracthostname+0x5c/0xa0 [cifs] ? extracthostname+0x5c/0xa0 [cifs] ? kmalloc+0x4b/0x140 reconnecttargetunlocked+0x3e/0x160 [cifs] reconnectdfsserver+0x145/0x430 [cifs] cifshandlestandard+0x1ad/0x1d0 [cifs] cifsdemultiplexthread+0x592/0x730 [cifs] ? pfxcifsdemultiplexthread+0x10/0x10 [cifs] kthread+0xdd/0x100 ? pfxkthread+0x10/0x10 retfromfork+0x29/0x50 </TASK>

Affected Software

189 affected componentsFixes available
Linux Linux kernel
Microsoft azl3 kernel 6.6.64.2-9<6.6.76.1-1
6.6.76.1-1
Microsoft azl3 kernel 6.6.76.1-1<6.6.76.1-1
6.6.76.1-1
Linux Linux kernel>=5.14.19<5.15
Linux Linux kernel>=5.15.3<6.6.74
Linux Linux kernel>=6.7<6.12.11
Linux Linux kernel=6.13-rc1
Linux Linux kernel=6.13-rc2
Linux Linux kernel=6.13-rc3
Linux Linux kernel=6.13-rc4
Linux Linux kernel=6.13-rc5
Linux Linux kernel=6.13-rc6
Linux Linux kernel=6.13-rc7
ubuntu/linux-hwe-edge*
ubuntu/linux-aws-5.4<5.4.0-1065.68~18.04.1
5.4.0-1065.68~18.04.1
ubuntu/linux-gcp-5.4<5.4.0-1064.68~18.04.1
5.4.0-1064.68~18.04.1
ubuntu/linux-hwe-5.4<5.4.0-99.112~18.04.1
5.4.0-99.112~18.04.1
ubuntu/linux-oracle-5.4<5.4.0-1063.67~18.04.1
5.4.0-1063.67~18.04.1
ubuntu/linux-aws-5.0*
ubuntu/linux-aws-5.3*
ubuntu/linux-azure*
ubuntu/linux-azure-5.3*
ubuntu/linux-azure-5.4*
ubuntu/linux-azure-edge*
ubuntu/linux-gcp*
ubuntu/linux-gcp-5.3*
ubuntu/linux-gke-4.15*
ubuntu/linux-gke-5.4*
ubuntu/linux-gkeop-5.4*
ubuntu/linux-hwe*
ubuntu/linux-hwe-edge*
ubuntu/linux-oem*
ubuntu/linux-oracle-5.0*
ubuntu/linux-oracle-5.3*
ubuntu/linux<5.4.0-99.112
5.4.0-99.112
ubuntu/linux-aws<5.4.0-1065.68
5.4.0-1065.68
ubuntu/linux-bluefield<5.4.0-1028.31
5.4.0-1028.31
ubuntu/linux-gcp<5.4.0-1064.68
5.4.0-1064.68
ubuntu/linux-ibm<5.4.0-1014.15
5.4.0-1014.15
ubuntu/linux-kvm<5.4.0-1055.57
5.4.0-1055.57
ubuntu/linux-oracle<5.4.0-1063.67
5.4.0-1063.67
ubuntu/linux-aws-5.11*
ubuntu/linux-aws-5.13*
ubuntu/linux-aws-5.15*
ubuntu/linux-aws-5.8*
ubuntu/linux-azure*
ubuntu/linux-azure-5.11*
ubuntu/linux-azure-5.13*
ubuntu/linux-azure-5.15*
ubuntu/linux-azure-5.8*
ubuntu/linux-azure-fde*
ubuntu/linux-azure-fde-5.15*
ubuntu/linux-gcp-5.11*
ubuntu/linux-gcp-5.13*
ubuntu/linux-gcp-5.15*
ubuntu/linux-gcp-5.8*
ubuntu/linux-gke*
ubuntu/linux-gke-5.15*
ubuntu/linux-gkeop*
ubuntu/linux-gkeop-5.15*
ubuntu/linux-hwe-5.11*
ubuntu/linux-hwe-5.13*
ubuntu/linux-hwe-5.15*
ubuntu/linux-hwe-5.8*
ubuntu/linux-ibm-5.15*
ubuntu/linux-intel-5.13*
ubuntu/linux-intel-iotg-5.15*
ubuntu/linux-lowlatency-hwe-5.15*
ubuntu/linux-nvidia-tegra-5.15*
ubuntu/linux-oem-5.10*
ubuntu/linux-oem-5.13*
ubuntu/linux-oem-5.6*
ubuntu/linux-oracle-5.11*
ubuntu/linux-oracle-5.13*
ubuntu/linux-oracle-5.15*
ubuntu/linux-oracle-5.8*
ubuntu/linux-raspi2*
ubuntu/linux-riscv*
ubuntu/linux-riscv-5.11*
ubuntu/linux-riscv-5.15*
ubuntu/linux-riscv-5.8*
ubuntu/linux-azure-fips*
ubuntu/linux-fips<5.4.0-1042.48
5.4.0-1042.48
ubuntu/linux*
ubuntu/linux-allwinner-5.19*
ubuntu/linux-aws*
ubuntu/linux-aws-5.19*
ubuntu/linux-aws-6.2*
ubuntu/linux-aws-6.5*
ubuntu/linux-aws-6.8<6.8.0-1030.32~22.04.1
6.8.0-1030.32~22.04.1
ubuntu/linux-azure*
ubuntu/linux-azure-5.19*
ubuntu/linux-azure-6.2*
ubuntu/linux-azure-6.5*
ubuntu/linux-azure-6.8<6.8.0-1030.35~22.04.1
6.8.0-1030.35~22.04.1
ubuntu/linux-azure-fde*
ubuntu/linux-azure-fde-5.19*
ubuntu/linux-azure-fde-6.2*
ubuntu/linux-gcp*
ubuntu/linux-gcp-5.19*
ubuntu/linux-gcp-6.2*
ubuntu/linux-gcp-6.5*
ubuntu/linux-gcp-6.8<6.8.0-1031.33~22.04.1
6.8.0-1031.33~22.04.1
ubuntu/linux-gke*
ubuntu/linux-gkeop*
ubuntu/linux-hwe-5.19*
ubuntu/linux-hwe-6.2*
ubuntu/linux-hwe-6.5*
ubuntu/linux-hwe-6.8<6.8.0-64.67~22.04.1
6.8.0-64.67~22.04.1
ubuntu/linux-ibm*
ubuntu/linux-ibm-6.8<6.8.0-1027.27~22.04.1
6.8.0-1027.27~22.04.1
ubuntu/linux-intel-iot-realtime*
ubuntu/linux-intel-iotg*
ubuntu/linux-kvm*
ubuntu/linux-lowlatency*
ubuntu/linux-lowlatency-hwe-5.19*
ubuntu/linux-lowlatency-hwe-6.2*
ubuntu/linux-lowlatency-hwe-6.5*
ubuntu/linux-lowlatency-hwe-6.8<6.8.0-62.65.1~22.04.1
6.8.0-62.65.1~22.04.1
ubuntu/linux-nvidia*
ubuntu/linux-nvidia-6.2*
ubuntu/linux-nvidia-6.5*
ubuntu/linux-nvidia-6.8<6.8.0-1029.32~22.04.1
6.8.0-1029.32~22.04.1
ubuntu/linux-nvidia-tegra*
ubuntu/linux-nvidia-tegra-igx*
ubuntu/linux-oem-5.17*
ubuntu/linux-oem-6.0*
ubuntu/linux-oem-6.1*
ubuntu/linux-oem-6.5*
ubuntu/linux-oracle*
ubuntu/linux-oracle-6.5*
ubuntu/linux-oracle-6.8<6.8.0-1027.28~22.04.1
6.8.0-1027.28~22.04.1
ubuntu/linux-raspi*
ubuntu/linux-realtime*
ubuntu/linux-riscv*
ubuntu/linux-riscv-5.19*
ubuntu/linux-riscv-6.5*
ubuntu/linux-riscv-6.8<6.8.0-62.65~22.04.1
6.8.0-62.65~22.04.1
ubuntu/linux-starfive-5.19*
ubuntu/linux-starfive-6.2*
ubuntu/linux-starfive-6.5*
ubuntu/linux-xilinx-zynqmp*
ubuntu/linux-bluefield*
ubuntu/linux-intel-iot-realtime*
ubuntu/linux-realtime*
ubuntu/linux-realtime-6.8<6.8.1-1023.24~22.04.1
6.8.1-1023.24~22.04.1
ubuntu/linux-aws-fips*
ubuntu/linux-azure-fips*
ubuntu/linux-fips*
ubuntu/linux-gcp-fips*
ubuntu/linux-aws-fips*
ubuntu/linux-azure-fips*
ubuntu/linux-fips*
ubuntu/linux-gcp-fips*
ubuntu/linux<6.8.0-62.65
6.8.0-62.65
ubuntu/linux-aws<6.8.0-1030.32
6.8.0-1030.32
ubuntu/linux-azure<6.8.0-1030.35
6.8.0-1030.35
ubuntu/linux-azure-6.11<6.11.0-1013.13~24.04.1
6.11.0-1013.13~24.04.1
ubuntu/linux-azure-nvidia<6.8.0-1018.19
6.8.0-1018.19
ubuntu/linux-gcp<6.8.0-1031.33
6.8.0-1031.33
ubuntu/linux-gcp-6.11<6.11.0-1013.13~24.04.1
6.11.0-1013.13~24.04.1
ubuntu/linux-gke<6.8.0-1026.30
6.8.0-1026.30
ubuntu/linux-gkeop<6.8.0-1013.15
6.8.0-1013.15
ubuntu/linux-hwe-6.11<6.11.0-24.24~24.04.1
6.11.0-24.24~24.04.1
ubuntu/linux-ibm<6.8.0-1027.27
6.8.0-1027.27
ubuntu/linux-lowlatency<6.8.0-62.65.1
6.8.0-62.65.1
ubuntu/linux-lowlatency-hwe-6.11<6.11.0-1012.13~24.04.1
6.11.0-1012.13~24.04.1
ubuntu/linux-nvidia<6.8.0-1029.32
6.8.0-1029.32
ubuntu/linux-nvidia-6.11<6.11.0-1007.7
6.11.0-1007.7
ubuntu/linux-nvidia-lowlatency<6.8.0-1029.32.1
6.8.0-1029.32.1
ubuntu/linux-nvidia-tegra<6.8.0-1008.8
6.8.0-1008.8
ubuntu/linux-oem-6.11<6.11.0-1020.20
6.11.0-1020.20
ubuntu/linux-oem-6.8<6.8.0-1029.29
6.8.0-1029.29
ubuntu/linux-oracle<6.8.0-1027.28
6.8.0-1027.28
ubuntu/linux-raspi<6.8.0-1029.33
6.8.0-1029.33
ubuntu/linux-raspi-realtime*
ubuntu/linux-realtime*
ubuntu/linux-riscv*
ubuntu/linux-xilinx<6.8.0-1017.18
6.8.0-1017.18
ubuntu/linux-raspi-realtime<6.8.0-2024.25
6.8.0-2024.25
ubuntu/linux-realtime<6.8.1-1023.24
6.8.1-1023.24
ubuntu/linux-fips<6.8.0-78.78+fips1
6.8.0-78.78+fips1
debian/linux*
debian/linux<6.12.11-1
6.12.11-1
debian/linux<6.12.11-1
6.12.11-1
linux/kernel>=5.16.0<6.1.191
6.1.191
linux/kernel>=6.2.0<6.6.74
6.6.74
linux/kernel>=6.7.0<6.12.11
6.12.11
debian/linux<=6.1.176-1, <=6.1.190-1
6.12.107-16.12.115-27.2.12-17.2.15-1

Remediation

Recommended actions to resolve this vulnerability, in priority order.

  1. Upgrade

    Upgrade to a fixed release to a version that resolves this vulnerability.

    Fixed in 6.6.76.1-1
  2. Upgrade

    Upgrade ubuntu/linux-aws-5.4 to a version that resolves this vulnerability.

    Fixed in 5.4.0-1065.68~18.04.1
  3. Upgrade

    Upgrade ubuntu/linux-gcp-5.4 to a version that resolves this vulnerability.

    Fixed in 5.4.0-1064.68~18.04.1
  4. Upgrade

    Upgrade ubuntu/linux-hwe-5.4 to a version that resolves this vulnerability.

    Fixed in 5.4.0-99.112~18.04.1
  5. Upgrade

    Upgrade ubuntu/linux-oracle-5.4 to a version that resolves this vulnerability.

    Fixed in 5.4.0-1063.67~18.04.1
  6. Upgrade

    Upgrade ubuntu/linux to a version that resolves this vulnerability.

    Fixed in 5.4.0-99.112
  7. Upgrade

    Upgrade ubuntu/linux-aws to a version that resolves this vulnerability.

    Fixed in 5.4.0-1065.68
  8. Upgrade

    Upgrade ubuntu/linux-bluefield to a version that resolves this vulnerability.

    Fixed in 5.4.0-1028.31
  9. Upgrade

    Upgrade ubuntu/linux-gcp to a version that resolves this vulnerability.

    Fixed in 5.4.0-1064.68
  10. Upgrade

    Upgrade ubuntu/linux-ibm to a version that resolves this vulnerability.

    Fixed in 5.4.0-1014.15
  11. Upgrade

    Upgrade ubuntu/linux-kvm to a version that resolves this vulnerability.

    Fixed in 5.4.0-1055.57
  12. Upgrade

    Upgrade ubuntu/linux-oracle to a version that resolves this vulnerability.

    Fixed in 5.4.0-1063.67
  13. Upgrade

    Upgrade ubuntu/linux-fips to a version that resolves this vulnerability.

    Fixed in 5.4.0-1042.48
  14. Upgrade

    Upgrade ubuntu/linux-aws-6.8 to a version that resolves this vulnerability.

    Fixed in 6.8.0-1030.32~22.04.1
  15. Upgrade

    Upgrade ubuntu/linux-azure-6.8 to a version that resolves this vulnerability.

    Fixed in 6.8.0-1030.35~22.04.1
  16. Upgrade

    Upgrade ubuntu/linux-gcp-6.8 to a version that resolves this vulnerability.

    Fixed in 6.8.0-1031.33~22.04.1
  17. Upgrade

    Upgrade ubuntu/linux-hwe-6.8 to a version that resolves this vulnerability.

    Fixed in 6.8.0-64.67~22.04.1
  18. Upgrade

    Upgrade ubuntu/linux-ibm-6.8 to a version that resolves this vulnerability.

    Fixed in 6.8.0-1027.27~22.04.1
  19. Upgrade

    Upgrade ubuntu/linux-lowlatency-hwe-6.8 to a version that resolves this vulnerability.

    Fixed in 6.8.0-62.65.1~22.04.1
  20. Upgrade

    Upgrade ubuntu/linux-nvidia-6.8 to a version that resolves this vulnerability.

    Fixed in 6.8.0-1029.32~22.04.1
  21. Upgrade

    Upgrade ubuntu/linux-oracle-6.8 to a version that resolves this vulnerability.

    Fixed in 6.8.0-1027.28~22.04.1
  22. Upgrade

    Upgrade ubuntu/linux-riscv-6.8 to a version that resolves this vulnerability.

    Fixed in 6.8.0-62.65~22.04.1
  23. Upgrade

    Upgrade ubuntu/linux-realtime-6.8 to a version that resolves this vulnerability.

    Fixed in 6.8.1-1023.24~22.04.1
  24. Upgrade

    Upgrade ubuntu/linux to a version that resolves this vulnerability.

    Fixed in 6.8.0-62.65
  25. Upgrade

    Upgrade ubuntu/linux-aws to a version that resolves this vulnerability.

    Fixed in 6.8.0-1030.32
  26. Upgrade

    Upgrade ubuntu/linux-azure to a version that resolves this vulnerability.

    Fixed in 6.8.0-1030.35
  27. Upgrade

    Upgrade ubuntu/linux-azure-6.11 to a version that resolves this vulnerability.

    Fixed in 6.11.0-1013.13~24.04.1
  28. Upgrade

    Upgrade ubuntu/linux-azure-nvidia to a version that resolves this vulnerability.

    Fixed in 6.8.0-1018.19
  29. Upgrade

    Upgrade ubuntu/linux-gcp to a version that resolves this vulnerability.

    Fixed in 6.8.0-1031.33
  30. Upgrade

    Upgrade ubuntu/linux-gcp-6.11 to a version that resolves this vulnerability.

    Fixed in 6.11.0-1013.13~24.04.1
  31. Upgrade

    Upgrade ubuntu/linux-gke to a version that resolves this vulnerability.

    Fixed in 6.8.0-1026.30
  32. Upgrade

    Upgrade ubuntu/linux-gkeop to a version that resolves this vulnerability.

    Fixed in 6.8.0-1013.15
  33. Upgrade

    Upgrade ubuntu/linux-hwe-6.11 to a version that resolves this vulnerability.

    Fixed in 6.11.0-24.24~24.04.1
  34. Upgrade

    Upgrade ubuntu/linux-ibm to a version that resolves this vulnerability.

    Fixed in 6.8.0-1027.27
  35. Upgrade

    Upgrade ubuntu/linux-lowlatency to a version that resolves this vulnerability.

    Fixed in 6.8.0-62.65.1
  36. Upgrade

    Upgrade ubuntu/linux-lowlatency-hwe-6.11 to a version that resolves this vulnerability.

    Fixed in 6.11.0-1012.13~24.04.1
  37. Upgrade

    Upgrade ubuntu/linux-nvidia to a version that resolves this vulnerability.

    Fixed in 6.8.0-1029.32
  38. Upgrade

    Upgrade ubuntu/linux-nvidia-6.11 to a version that resolves this vulnerability.

    Fixed in 6.11.0-1007.7
  39. Upgrade

    Upgrade ubuntu/linux-nvidia-lowlatency to a version that resolves this vulnerability.

    Fixed in 6.8.0-1029.32.1
  40. Upgrade

    Upgrade ubuntu/linux-nvidia-tegra to a version that resolves this vulnerability.

    Fixed in 6.8.0-1008.8
  41. Upgrade

    Upgrade ubuntu/linux-oem-6.11 to a version that resolves this vulnerability.

    Fixed in 6.11.0-1020.20
  42. Upgrade

    Upgrade ubuntu/linux-oem-6.8 to a version that resolves this vulnerability.

    Fixed in 6.8.0-1029.29
  43. Upgrade

    Upgrade ubuntu/linux-oracle to a version that resolves this vulnerability.

    Fixed in 6.8.0-1027.28
  44. Upgrade

    Upgrade ubuntu/linux-raspi to a version that resolves this vulnerability.

    Fixed in 6.8.0-1029.33
  45. Upgrade

    Upgrade ubuntu/linux-xilinx to a version that resolves this vulnerability.

    Fixed in 6.8.0-1017.18
  46. Upgrade

    Upgrade ubuntu/linux-raspi-realtime to a version that resolves this vulnerability.

    Fixed in 6.8.0-2024.25
  47. Upgrade

    Upgrade ubuntu/linux-realtime to a version that resolves this vulnerability.

    Fixed in 6.8.1-1023.24
  48. Upgrade

    Upgrade ubuntu/linux-fips to a version that resolves this vulnerability.

    Fixed in 6.8.0-78.78+fips1
  49. Upgrade

    Upgrade debian/linux to a version that resolves this vulnerability.

    Fixed in 6.12.11-1
  50. Upgrade

    Upgrade debian/linux to a version that resolves this vulnerability.

    Fixed in 6.12.107-1Fixed in 6.12.113-1Fixed in 7.2.12-1Fixed in 7.2.14-1
  51. Upgrade

    Upgrade linux/Kernel to a version that resolves this vulnerability.

    Fixed in 6.1.191
  52. Upgrade

    Upgrade linux/Kernel to a version that resolves this vulnerability.

    Fixed in 6.6.74
  53. Upgrade

    Upgrade linux/Kernel to a version that resolves this vulnerability.

    Fixed in 6.12.11

Event History

Jan 31, 2025
CVE Published
via MITRE·11:25 AM
Data Sourced
via MITRE·11:25 AM
DescriptionSeverity
Data Sourced
via OSV·11:25 AM
DescriptionSeverityAffected Software
Data Sourced
via NVD·12:15 PM
RemedyDescriptionSeverityWeaknessAffected Software
Mar 14, 2025
Data Sourced
via Microsoft·07:00 AM
DescriptionSeverityWeaknessAffected Software

Frequently Asked Questions

1

What is the severity of CVE-2025-21673?

CVE-2025-21673 is rated as a medium severity vulnerability.

2

How do I fix CVE-2025-21673?

Fixing CVE-2025-21673 involves updating to the latest version of the Linux kernel where this vulnerability has been patched.

3

What types of systems are affected by CVE-2025-21673?

CVE-2025-21673 affects systems running the Linux kernel, specifically those utilizing SMB client functionality.

4

What is the potential impact of CVE-2025-21673?

The potential impact of CVE-2025-21673 includes the risk of a double free vulnerability leading to arbitrary code execution or denial of service.

5

When was CVE-2025-21673 disclosed?

CVE-2025-21673 was disclosed as part of a series of kernel vulnerabilities addressing SMB client issues.

Company

Resources

Contact

SecAlerts Pty Ltd.
132 Wickham Terrace
Fortitude Valley,
QLD 4006, Australia
info@secalerts.co
By using SecAlerts services, you agree to our services end-user license agreement. This website is safeguarded by reCAPTCHA and governed by the Google Privacy Policy and Terms of Service. All names, logos, and brands of products are owned by their respective owners, and any usage of these names, logos, and brands for identification purposes only does not imply endorsement. If you possess any content that requires removal, please get in touch with us.
© 2026 SecAlerts Pty Ltd.
ABN: 70 645 966 203, ACN: 645 966 203