firmware: arm_scpi: Check the DVFS OPP count returned by the firmware

[ Upstream commit 109aa65 ]

Fix a kernel crash with the below call trace when the SCPI firmware
returns OPP count of zero.

dvfs_info.opp_count may be zero on some platforms during the reboot
test, and the kernel will crash after dereferencing the pointer to
kcalloc(info->count, sizeof(*opp), GFP_KERNEL).

  |  Unable to handle kernel NULL pointer dereference at virtual address 0000000000000028
  |  Mem abort info:
  |    ESR = 0x96000004
  |    Exception class = DABT (current EL), IL = 32 bits
  |    SET = 0, FnV = 0
  |    EA = 0, S1PTW = 0
  |  Data abort info:
  |    ISV = 0, ISS = 0x00000004
  |    CM = 0, WnR = 0
  |  user pgtable: 4k pages, 48-bit VAs, pgdp = 00000000faefa08c
  |  [0000000000000028] pgd=0000000000000000
  |  Internal error: Oops: 96000004 [#1] SMP
  |  scpi-hwmon: probe of PHYT000D:00 failed with error -110
  |  Process systemd-udevd (pid: 1701, stack limit = 0x00000000aaede86c)
  |  CPU: 2 PID: 1701 Comm: systemd-udevd Not tainted 4.19.90+ #1
  |  Hardware name: PHYTIUM LTD Phytium FT2000/4/Phytium FT2000/4, BIOS
  |  pstate: 60000005 (nZCv daif -PAN -UAO)
  |  pc : scpi_dvfs_recalc_rate+0x40/0x58 [clk_scpi]
  |  lr : clk_register+0x438/0x720
  |  Call trace:
  |   scpi_dvfs_recalc_rate+0x40/0x58 [clk_scpi]
  |   devm_clk_hw_register+0x50/0xa0
  |   scpi_clk_ops_init.isra.2+0xa0/0x138 [clk_scpi]
  |   scpi_clocks_probe+0x528/0x70c [clk_scpi]
  |   platform_drv_probe+0x58/0xa8
  |   really_probe+0x260/0x3d0
  |   driver_probe_device+0x12c/0x148
  |   device_driver_attach+0x74/0x98
  |   __driver_attach+0xb4/0xe8
  |   bus_for_each_dev+0x88/0xe0
  |   driver_attach+0x30/0x40
  |   bus_add_driver+0x178/0x2b0
  |   driver_register+0x64/0x118
  |   __platform_driver_register+0x54/0x60
  |   scpi_clocks_driver_init+0x24/0x1000 [clk_scpi]
  |   do_one_initcall+0x54/0x220
  |   do_init_module+0x54/0x1c8
  |   load_module+0x14a4/0x1668
  |   __se_sys_finit_module+0xf8/0x110
  |   __arm64_sys_finit_module+0x24/0x30
  |   el0_svc_common+0x78/0x170
  |   el0_svc_handler+0x38/0x78
  |   el0_svc+0x8/0x340
  |  Code: 937d7c00 a94153f3 a8c27bfd f9400421 (b8606820)
  |  ---[ end trace 06feb22469d89fa8 ]---
  |  Kernel panic - not syncing: Fatal exception
  |  SMP: stopping secondary CPUs
  |  Kernel Offset: disabled
  |  CPU features: 0x10,a0002008
  |  Memory Limit: none

Fixes: 8cb7cf5 ("firmware: add support for ARM System Control and Power Interface(SCPI) protocol")
Signed-off-by: Luo Qiu <[email protected]>
Message-Id: <[email protected]>
Signed-off-by: Sudeep Holla <[email protected]>
Signed-off-by: Sasha Levin <[email protected]>

drivers/firmware/arm_scpi.c

@@ -627,6 +627,9 @@ static struct scpi_dvfs_info *scpi_dvfs_get_info(u8 domain)
 	if (ret)
 		return ERR_PTR(ret);
 
+	if (!buf.opp_count)
+		return ERR_PTR(-ENOENT);
+
 	info = kmalloc(sizeof(*info), GFP_KERNEL);
 	if (!info)
 		return ERR_PTR(-ENOMEM);