Linux Kernel up to 6.12.24/6.14.3/6.15-rc2 slab __alloc_tagging_slab_alloc_hook null pointer dereference

Summaryinfo

A vulnerability has been found in Linux Kernel up to 6.12.24/6.14.3/6.15-rc2 and classified as critical. This issue affects the function __alloc_tagging_slab_alloc_hook of the component slab. The manipulation leads to null pointer dereference. This vulnerability is uniquely identified as CVE-2025-37774. No exploit exists. The affected component should be upgraded.

Detailsinfo

A vulnerability was found in Linux Kernel up to 6.12.24/6.14.3/6.15-rc2. It has been rated as critical. This issue affects the function __alloc_tagging_slab_alloc_hook of the component slab. The manipulation with an unknown input leads to a null pointer dereference vulnerability. Using CWE to declare the problem leads to CWE-476. A NULL pointer dereference occurs when the application dereferences a pointer that it expects to be valid, but is NULL, typically causing a crash or exit. Impacted is availability. The summary by CVE is:

In the Linux kernel, the following vulnerability has been resolved: slab: ensure slab->obj_exts is clear in a newly allocated slab page ktest recently reported crashes while running several buffered io tests with __alloc_tagging_slab_alloc_hook() at the top of the crash call stack. The signature indicates an invalid address dereference with low bits of slab->obj_exts being set. The bits were outside of the range used by page_memcg_data_flags and objext_flags and hence were not masked out by slab_obj_exts() when obtaining the pointer stored in slab->obj_exts. The typical crash log looks like this: 00510 Unable to handle kernel NULL pointer dereference at virtual address 0000000000000010 00510 Mem abort info: 00510 ESR = 0x0000000096000045 00510 EC = 0x25: DABT (current EL), IL = 32 bits 00510 SET = 0, FnV = 0 00510 EA = 0, S1PTW = 0 00510 FSC = 0x05: level 1 translation fault 00510 Data abort info: 00510 ISV = 0, ISS = 0x00000045, ISS2 = 0x00000000 00510 CM = 0, WnR = 1, TnD = 0, TagAccess = 0 00510 GCS = 0, Overlay = 0, DirtyBit = 0, Xs = 0 00510 user pgtable: 4k pages, 39-bit VAs, pgdp=0000000104175000 00510 [0000000000000010] pgd=0000000000000000, p4d=0000000000000000, pud=0000000000000000 00510 Internal error: Oops: 0000000096000045 [#1] SMP 00510 Modules linked in: 00510 CPU: 10 UID: 0 PID: 7692 Comm: cat Not tainted 6.15.0-rc1-ktest-g189e17946605 #19327 NONE 00510 Hardware name: linux,dummy-virt (DT) 00510 pstate: 20001005 (nzCv daif -PAN -UAO -TCO -DIT +SSBS BTYPE=--) 00510 pc : __alloc_tagging_slab_alloc_hook+0xe0/0x190 00510 lr : __kmalloc_noprof+0x150/0x310 00510 sp : ffffff80c87df6c0 00510 x29: ffffff80c87df6c0 x28: 000000000013d1ff x27: 000000000013d200 00510 x26: ffffff80c87df9e0 x25: 0000000000000000 x24: 0000000000000001 00510 x23: ffffffc08041953c x22: 000000000000004c x21: ffffff80c0002180 00510 x20: fffffffec3120840 x19: ffffff80c4821000 x18: 0000000000000000 00510 x17: fffffffec3d02f00 x16: fffffffec3d02e00 x15: fffffffec3d00700 00510 x14: fffffffec3d00600 x13: 0000000000000200 x12: 0000000000000006 00510 x11: ffffffc080bb86c0 x10: 0000000000000000 x9 : ffffffc080201e58 00510 x8 : ffffff80c4821060 x7 : 0000000000000000 x6 : 0000000055555556 00510 x5 : 0000000000000001 x4 : 0000000000000010 x3 : 0000000000000060 00510 x2 : 0000000000000000 x1 : ffffffc080f50cf8 x0 : ffffff80d801d000 00510 Call trace: 00510 __alloc_tagging_slab_alloc_hook+0xe0/0x190 (P) 00510 __kmalloc_noprof+0x150/0x310 00510 __bch2_folio_create+0x5c/0xf8 00510 bch2_folio_create+0x2c/0x40 00510 bch2_readahead+0xc0/0x460 00510 read_pages+0x7c/0x230 00510 page_cache_ra_order+0x244/0x3a8 00510 page_cache_async_ra+0x124/0x170 00510 filemap_readahead.isra.0+0x58/0xa0 00510 filemap_get_pages+0x454/0x7b0 00510 filemap_read+0xdc/0x418 00510 bch2_read_iter+0x100/0x1b0 00510 vfs_read+0x214/0x300 00510 ksys_read+0x6c/0x108 00510 __arm64_sys_read+0x20/0x30 00510 invoke_syscall.constprop.0+0x54/0xe8 00510 do_el0_svc+0x44/0xc8 00510 el0_svc+0x18/0x58 00510 el0t_64_sync_handler+0x104/0x130 00510 el0t_64_sync+0x154/0x158 00510 Code: d5384100 f9401c01 b9401aa3 b40002e1 (f8227881) 00510 ---[ end trace 0000000000000000 ]--- 00510 Kernel panic - not syncing: Oops: Fatal exception 00510 SMP: stopping secondary CPUs 00510 Kernel Offset: disabled 00510 CPU features: 0x0000,000000e0,00000410,8240500b 00510 Memory Limit: none Investigation indicates that these bits are already set when we allocate slab page and are not zeroed out after allocation. We are not yet sure why these crashes start happening only recently but regardless of the reason, not initializing a field that gets used later is wrong. Fix it by initializing slab->obj_exts during slab page allocation.

It is possible to read the advisory at git.kernel.org. The identification of this vulnerability is CVE-2025-37774 since 04/16/2025. The exploitation is known to be difficult. Technical details of the vulnerability are known, but there is no available exploit.

The vulnerability scanner Nessus provides a plugin with the ID 240657 (Ubuntu 25.04 : Linux kernel vulnerabilities (USN-7594-1)), which helps to determine the existence of the flaw in a target environment.

Upgrading to version 6.12.25, 6.14.4 or 6.15-rc3 eliminates this vulnerability. Applying the patch 8baa747193591410a853bac9c3710142dfa4937b/28bef6622a1a874fe63aceeb0c684fab75afb3ae/d2f5819b6ed357c0c350c0616b6b9f38be59adf6 is able to eliminate this problem. The bugfix is ready for download at git.kernel.org. The best possible mitigation is suggested to be upgrading to the latest version.

The vulnerability is also documented in the databases at Tenable (240657) and CERT Bund (WID-SEC-2025-0922). Statistical analysis made it clear that VulDB provides the best quality for vulnerability data.

Affected

• Google Container-Optimized OS
• Debian Linux
• Amazon Linux 2
• Red Hat Enterprise Linux
• Ubuntu Linux
• SUSE Linux
• Oracle Linux
• SUSE openSUSE
• RESF Rocky Linux
• Dell Avamar
• Open Source Linux Kernel
• IBM DataPower Gateway
• Dell NetWorker
• Dell Secure Connect Gateway

Productinfo

Type

• Operating System

Vendor

• Linux

Name

• Kernel

Version

• 6.12.0
• 6.12.1
• 6.12.2
• 6.12.3
• 6.12.4
• 6.12.5
• 6.12.6
• 6.12.7
• 6.12.8
• 6.12.9
• 6.12.10
• 6.12.11
• 6.12.12
• 6.12.13
• 6.12.14
• 6.12.15
• 6.12.16
• 6.12.17
• 6.12.18
• 6.12.19
• 6.12.20
• 6.12.21
• 6.12.22
• 6.12.23
• 6.12.24
• 6.14.0
• 6.14.1
• 6.14.2
• 6.14.3
• 6.15-rc1
• 6.15-rc2

License

• open-source

Website

• Vendor: https://www.kernel.org/

CPE 2.3info

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CPE 2.2info

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Exploitinginfo

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Entryinfo

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