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Medium severity5.5NVD Advisory· Published Apr 17, 2024· Updated May 12, 2026

CVE-2024-26901

CVE-2024-26901

Description

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

do_sys_name_to_handle(): use kzalloc() to fix kernel-infoleak

syzbot identified a kernel information leak vulnerability in do_sys_name_to_handle() and issued the following report [1].

[1] "BUG: KMSAN: kernel-infoleak in instrument_copy_to_user include/linux/instrumented.h:114 [inline] BUG: KMSAN: kernel-infoleak in _copy_to_user+0xbc/0x100 lib/usercopy.c:40 instrument_copy_to_user include/linux/instrumented.h:114 [inline] _copy_to_user+0xbc/0x100 lib/usercopy.c:40 copy_to_user include/linux/uaccess.h:191 [inline] do_sys_name_to_handle fs/fhandle.c:73 [inline] __do_sys_name_to_handle_at fs/fhandle.c:112 [inline] __se_sys_name_to_handle_at+0x949/0xb10 fs/fhandle.c:94 __x64_sys_name_to_handle_at+0xe4/0x140 fs/fhandle.c:94 ...

Uninit was created at: slab_post_alloc_hook+0x129/0xa70 mm/slab.h:768 slab_alloc_node mm/slub.c:3478 [inline] __kmem_cache_alloc_node+0x5c9/0x970 mm/slub.c:3517 __do_kmalloc_node mm/slab_common.c:1006 [inline] __kmalloc+0x121/0x3c0 mm/slab_common.c:1020 kmalloc include/linux/slab.h:604 [inline] do_sys_name_to_handle fs/fhandle.c:39 [inline] __do_sys_name_to_handle_at fs/fhandle.c:112 [inline] __se_sys_name_to_handle_at+0x441/0xb10 fs/fhandle.c:94 __x64_sys_name_to_handle_at+0xe4/0x140 fs/fhandle.c:94 ...

Bytes 18-19 of 20 are uninitialized Memory access of size 20 starts at ffff888128a46380 Data copied to user address 0000000020000240"

Per Chuck Lever's suggestion, use kzalloc() instead of kmalloc() to solve the problem.

AI Insight

LLM-synthesized narrative grounded in this CVE's description and references.

CVE-2024-26901 is a medium-severity kernel information leak in do_sys_name_to_handle() fixed by using kzalloc() to prevent uninitialized memory being copied to user space.

Vulnerability

Description

CVE-2024-26901 is a kernel information leak vulnerability in the Linux kernel's do_sys_name_to_handle() function located in fs/fhandle.c. The function used kmalloc() to allocate a 20-byte structure without initializing the memory, leaving bytes 18-19 uninitialized. This uninitialized memory was subsequently copied to user space via copy_to_user(), exposing potentially sensitive kernel heap data to unprivileged user processes [1][3][4].

Exploitation

Prerequisites

An attacker can trigger this leak via the name_to_handle_at() system call. No special privileges are required other than the ability to invoke the syscall, which is accessible to unprivileged users in default configurations. The attacker must be able to interact with the syscall interface, but no authentication or local access beyond a user account is needed. The information leak occurs because the kernel fails to zero the allocated memory before copying it to the user-supplied buffer [1].

Impact

A local user can exploit this bug to read 2 uninitialized bytes from kernel heap memory. This leak can reveal sensitive information such as kernel pointers, slab metadata, or data from other processes that previously occupied the same memory region. While the leak is small (2 bytes per invocation), repeated calls can gradually build a picture of kernel memory layout, aiding further exploitation [1]. The CVSS v3 base score is 5.5 (Medium) reflecting the local attack vector and low complexity [1].

Mitigation

The fix, committed in the Linux kernel stable tree, replaces kmalloc() with kzalloc(), which zero-initializes the allocated memory [3][4]. Users should update to a kernel version containing the commit. Affected products include Siemens SIMATIC S7-1500 TM MFP - GNU/Linux subsystem, which is listed as affected by this CVE among many others [1][2].

References
  1. SSA-265688
  2. SSA-398330
  3. Making sure you're not a bot!
  4. Making sure you're not a bot!

AI Insight generated on May 20, 2026. Synthesized from this CVE's description and the cited reference URLs; citations are validated against the source bundle.

Affected products

152

Patches

0

No patches discovered yet.

Vulnerability mechanics

AI mechanics synthesis has not run for this CVE yet.

References

13

News mentions

0

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