In the Linux kernel, the following vulnerability has been resolved:
ASoC: SOF: Intel: hda: Fix UAF when reloading module
hdagenericmachineselect() appends -idisp to the tplg filename by allocating a new string with devmkasprintf(), then stores the string right back into the global variable sndsocacpiintelhda_machines. When the module is unloaded, this memory is freed, resulting in a global variable pointing to freed memory. Reloading the module then triggers a use-after-free:
BUG: KFENCE: use-after-free read in string+0x48/0xe0
Use-after-free read at 0x00000000967e0109 (in kfence-#99): string+0x48/0xe0 vsnprintf+0x329/0x6e0 devmkvasprintf+0x54/0xb0 devmkasprintf+0x58/0x80 hdamachineselect.cold+0x198/0x17a2 [sndsofintelhdageneric] sofprobework+0x7f/0x600 [sndsof] processonework+0x17b/0x330 workerthread+0x2ce/0x3f0 kthread+0xcf/0x100 retfromfork+0x31/0x50 retfromfork_asm+0x1a/0x30
kfence-#99: 0x00000000198a940f-0x00000000ace47d9d, size=64, cache=kmalloc-64
allocated by task 333 on cpu 8 at 17.798069s (130.453553s ago): devmkmalloc+0x52/0x120 devmkvasprintf+0x66/0xb0 devmkasprintf+0x58/0x80 hdamachineselect.cold+0x198/0x17a2 [sndsofintelhdageneric] sofprobework+0x7f/0x600 [sndsof] processonework+0x17b/0x330 workerthread+0x2ce/0x3f0 kthread+0xcf/0x100 retfromfork+0x31/0x50 retfromforkasm+0x1a/0x30
freed by task 1543 on cpu 4 at 141.586686s (6.665010s ago): releasenodes+0x43/0xb0 devresreleaseall+0x90/0xf0 deviceunbindcleanup+0xe/0x70 devicereleasedriverinternal+0x1c1/0x200 driverdetach+0x48/0x90 busremovedriver+0x6d/0xf0 pciunregisterdriver+0x42/0xb0 _dosysdeletemodule+0x1d1/0x310 dosyscall64+0x82/0x190 entrySYSCALL64after_hwframe+0x76/0x7e
Fix it by copying the match array with devmkmemduparray() before we modify it.