[kernel-6.5-bug] with xen-4.18~rc4 on ub-24.04 noble, booting xen domU shows UBSAN errors in blkback & netback drivers

[Pry Mar <pryorm09@xxxxxxxxx>]

Hello,

These 2 errors show in dmesg late in boot process when xen domU launch:

1)  blkback

UBSAN: array-index-out-of-bounds in /build/linux-D15vQj/linux-6.5.0/drivers/block/xen-blkback/blkback.c:1227:4

2) netback

[   55.209063] UBSAN: array-index-out-of-bounds in /build/linux-D15vQj/linux-6.5.0/drivers/net/xen-netback/netback.c:289:3
[   55.209268] index 3 is out of range for type 'xen_netif_tx_sring_entry [1]'
[   55.209401] CPU: 3 PID: 0 Comm: swapper/3 Not tainted 6.5.0-9-generic #9-Ubuntu

The xen sources don't seem to generate these UBSAN errors and I included the patch from staging-4.18. It seems only the xen related kernel drivers are

doing UBSAN errors.

BTW the dom0 works fine. The xen-4.18~rc4 debian delta was a forward port from Jammy.

cheers,

PryMar56

##xen-packaging on OFTC