CVE-2024-56652

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

drm/xe/reg_sr: Remove register pool

That pool implementation doesnt really work: if the krealloc happens to move the memory and return another address, the entries in the xarray become invalid, leading to use-after-free later:

BUG: KASAN: slab-use-after-free in xe_reg_sr_apply_mmio+0x570/0x760 [xe]
Read of size 4 at addr ffff8881244b2590 by task modprobe/2753

Allocated by task 2753:
 kasan_save_stack+0x39/0x70
 kasan_save_track+0x14/0x40
 kasan_save_alloc_info+0x37/0x60
 __kasan_kmalloc+0xc3/0xd0
 __kmalloc_node_track_caller_noprof+0x200/0x6d0
 krealloc_noprof+0x229/0x380

Simplify the code to fix the bug. A better pooling strategy may be added back later if needed.

(cherry picked from commit e5283bd4dfecbd3335f43b62a68e24dae23f59e4)

Weakness

The product reuses or references memory after it has been freed. At some point afterward, the memory may be allocated again and saved in another pointer, while the original pointer references a location somewhere within the new allocation. Any operations using the original pointer are no longer valid because the memory “belongs” to the code that operates on the new pointer.

Affected Software

Potential Mitigations

References

• https://git.kernel.org/stable/c/b0193a31a0ca5a0f9e60bb4a86537d46b98111b8
• https://git.kernel.org/stable/c/d7b028656c29b22fcde1c6ee1df5b28fbba987b5