CVE-2024-46847: mm: vmalloc: ensure vmap_block is initialised before adding to queue
First published: Fri Sep 27 2024(Updated: )
In the Linux kernel, the following vulnerability has been resolved: mm: vmalloc: ensure vmap_block is initialised before adding to queue Commit 8c61291fd850 ("mm: fix incorrect vbq reference in purge_fragmented_block") extended the 'vmap_block' structure to contain a 'cpu' field which is set at allocation time to the id of the initialising CPU. When a new 'vmap_block' is being instantiated by new_vmap_block(), the partially initialised structure is added to the local 'vmap_block_queue' xarray before the 'cpu' field has been initialised. If another CPU is concurrently walking the xarray (e.g. via vm_unmap_aliases()), then it may perform an out-of-bounds access to the remote queue thanks to an uninitialised index. This has been observed as UBSAN errors in Android: | Internal error: UBSAN: array index out of bounds: 00000000f2005512 [#1] PREEMPT SMP | | Call trace: | purge_fragmented_block+0x204/0x21c | _vm_unmap_aliases+0x170/0x378 | vm_unmap_aliases+0x1c/0x28 | change_memory_common+0x1dc/0x26c | set_memory_ro+0x18/0x24 | module_enable_ro+0x98/0x238 | do_init_module+0x1b0/0x310 Move the initialisation of 'vb->cpu' in new_vmap_block() ahead of the addition to the xarray.
Credit: 416baaa9-dc9f-4396-8d5f-8c081fb06d67 416baaa9-dc9f-4396-8d5f-8c081fb06d67
| Affected Software | Affected Version | How to fix |
|---|---|---|
| Linux Kernel | >=6.6.37<6.6.51 | |
| Linux Kernel | >=6.9.8<6.10 | |
| Linux Kernel | >=6.10<6.10.10 | |
| Linux Kernel | =6.11-rc1 | |
| Linux Kernel | =6.11-rc2 | |
| Linux Kernel | =6.11-rc3 | |
| Linux Kernel | =6.11-rc4 | |
| Linux Kernel | =6.11-rc5 | |
| Linux Kernel | =6.11-rc6 | |
| debian/linux | 5.10.223-1 5.10.234-1 6.1.129-1 6.1.135-1 6.12.22-1 6.12.25-1 |
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Reference Links
- https://git.kernel.org/stable/c/1b2770e27d6d952f491bb362b657e5b2713c3efd
- https://git.kernel.org/stable/c/3e3de7947c751509027d26b679ecd243bc9db255
- https://git.kernel.org/stable/c/6cf74e0e5e3ab5d5c9defb4c73dad54d52224671
- https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2024-46847
- https://nvd.nist.gov/vuln/detail/CVE-2024-46847
- https://launchpad.net/bugs/cve/CVE-2024-46847
- https://security-tracker.debian.org/tracker/CVE-2024-46847
- https://ubuntu.com/security/CVE-2024-46847
- https://git.kernel.org/linus/3e3de7947c751509027d26b679ecd243bc9db255
Frequently Asked Questions
What is the severity of CVE-2024-46847?
The severity of CVE-2024-46847 is classified as medium risk.
How do I fix CVE-2024-46847?
To fix CVE-2024-46847, update the Linux kernel to a version that is not affected by this vulnerability.
Which versions of Linux kernel are affected by CVE-2024-46847?
CVE-2024-46847 affects Linux kernel versions between 6.6.37 and 6.6.51, 6.9.8 and 6.10, and multiple release candidates of 6.11.
Is there a patch available for CVE-2024-46847?
Yes, a patch for CVE-2024-46847 is available in the updated versions of the Linux kernel.
What is the cause of CVE-2024-46847?
CVE-2024-46847 is caused by improper initialization of the 'vmap_block' structure in the Linux kernel.
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