irqchip/riscv-imsic: Reject overlapping group index fields

The IMSIC address layout places the group index above the page offset,
guest index and HART index. imsic_parse_fwnode() checks the individual
field widths and the upper end of the group field, but does not check
that its lower end is above the other fields.

Reject a nonzero group field whose shift overlaps the lower fields.
Otherwise a firmware-supplied layout can assign the same address bit to
different indices when MSI target addresses are constructed.

Keep the existing upper-bound check unchanged. The new lower-bound
check applies only when group index bits are present.

The issue was found by our static-analysis tool.

Fixes: 21a8f8a0eb35 ("irqchip: Add RISC-V incoming MSI controller early driver")
Signed-off-by: Pengpeng Hou <hppiscas@163.com>
Signed-off-by: Thomas Gleixner <tglx@kernel.org>
Assisted-by: gpt 5
Reviewed-by: Anup Patel <anup@brainfault.org>
Link: https://patch.msgid.link/caplitmus-rv.v2.imsic.f2c0e5bdc627451c83deb0cf7eb8834a@163.com

0 files changed, 0 insertions, 0 deletions