CVE Published: 27/09/2024 |
CVE Updated: 05/11/2024 |
CVE Year: 2024 Source: Linux |
Vendor: Linux |
Product: Linux Status : PUBLISHED
CVE-2024-46847 Description
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.