CVE-2024-56544: udmabuf: change folios array from kmalloc to kvmalloc

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

udmabuf: change folios array from kmalloc to kvmalloc

When PAGESIZE 4096, MAXPAGEORDER 10, 64bit machine, pagealloc only support 4MB. If above this, trigger this warn and return NULL.

udmabuf can change size limit, if change it to 3072(3GB), and then alloc 3GB udmabuf, will fail create.

[ 4080.876581] ------------[ cut here ]------------ [ 4080.876843] WARNING: CPU: 3 PID: 2015 at mm/pagealloc.c:4556 allocpages+0x2c8/0x350 [ 4080.878839] RIP: 0010:allocpages+0x2c8/0x350 [ 4080.879470] Call Trace: [ 4080.879473] <TASK> [ 4080.879473] ? allocpages+0x2c8/0x350 [ 4080.879475] ? warn.cold+0x8e/0xe8 [ 4080.880647] ? allocpages+0x2c8/0x350 [ 4080.880909] ? reportbug+0xff/0x140 [ 4080.881175] ? handlebug+0x3c/0x80 [ 4080.881556] ? excinvalidop+0x17/0x70 [ 4080.881559] ? asmexcinvalidop+0x1a/0x20 [ 4080.882077] ? udmabufcreate+0x131/0x400

Because MAXPAGEORDER, kmalloc can max alloc 4096 (1 << 10), 4MB memory, each array entry is pointer(8byte), so can save 524288 pages(2GB).

Further more, costly order(order 3) may not be guaranteed that it can be applied for, due to fragmentation.

This patch change udmabuf array use kvmallocarray, this can fallback alloc into vmalloc, which can guarantee allocation for any size and does not affect the performance of kmalloc allocations.