If xhci_mem_init() fails, it calls into xhci_mem_cleanup() to mop
up the damage. If it fails early enough, before xhci->interrupters
is allocated but after xhci->max_interrupters has been set, which
happens in most (all?) cases, things get uglier, as xhci_mem_cleanup()
unconditionally derefences xhci->interrupters. With prejudice.
Gate the interrupt freeing loop with a check on xhci->interrupters
being non-NULL.
Found while debugging a DMA allocation issue that led the XHCI driver
on this exact path.
Fixes: c99b38c41234 ("xhci: add support to allocate several interrupters")
Cc: Mathias Nyman <mathias.nyman@xxxxxxxxxxxxxxx>
Cc: Wesley Cheng <quic_wcheng@xxxxxxxxxxx>
Cc: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
Signed-off-by: Marc Zyngier <maz@xxxxxxxxxx>
---