[ Upstream commit efdde3d ]

There is case as below could trigger kernel dump:
Use U-Boot to start remote processor(rproc) with resource table
published to a fixed address by rproc. After Kernel boots up,
stop the rproc, load a new firmware which doesn't have resource table
,and start rproc.

When starting rproc with a firmware not have resource table,
`memcpy(loaded_table, rproc->cached_table, rproc->table_sz)` will
trigger dump, because rproc->cache_table is set to NULL during the last
stop operation, but rproc->table_sz is still valid.

This issue is found on i.MX8MP and i.MX9.

Dump as below:
Unable to handle kernel NULL pointer dereference at virtual address 0000000000000000
Mem abort info:
  ESR = 0x0000000096000004
  EC = 0x25: DABT (current EL), IL = 32 bits
  SET = 0, FnV = 0
  EA = 0, S1PTW = 0
  FSC = 0x04: level 0 translation fault
Data abort info:
  ISV = 0, ISS = 0x00000004, ISS2 = 0x00000000
  CM = 0, WnR = 0, TnD = 0, TagAccess = 0
  GCS = 0, Overlay = 0, DirtyBit = 0, Xs = 0
user pgtable: 4k pages, 48-bit VAs, pgdp=000000010af63000
[0000000000000000] pgd=0000000000000000, p4d=0000000000000000
Internal error: Oops: 0000000096000004 [#1] PREEMPT SMP
Modules linked in:
CPU: 2 UID: 0 PID: 1060 Comm: sh Not tainted 6.14.0-rc7-next-20250317-dirty #38
Hardware name: NXP i.MX8MPlus EVK board (DT)
pstate: a0000005 (NzCv daif -PAN -UAO -TCO -DIT -SSBS BTYPE=--)
pc : __pi_memcpy_generic+0x110/0x22c
lr : rproc_start+0x88/0x1e0
Call trace:
 __pi_memcpy_generic+0x110/0x22c (P)
 rproc_boot+0x198/0x57c
 state_store+0x40/0x104
 dev_attr_store+0x18/0x2c
 sysfs_kf_write+0x7c/0x94
 kernfs_fop_write_iter+0x120/0x1cc
 vfs_write+0x240/0x378
 ksys_write+0x70/0x108
 __arm64_sys_write+0x1c/0x28
 invoke_syscall+0x48/0x10c
 el0_svc_common.constprop.0+0xc0/0xe0
 do_el0_svc+0x1c/0x28
 el0_svc+0x30/0xcc
 el0t_64_sync_handler+0x10c/0x138
 el0t_64_sync+0x198/0x19c

Clear rproc->table_sz to address the issue.

Fixes: 9dc9507 ("remoteproc: Properly deal with the resource table when detaching")
Signed-off-by: Peng Fan <peng.fan@nxp.com>
Link: https://lore.kernel.org/r/20250319100106.3622619-1-peng.fan@oss.nxp.com
Signed-off-by: Bjorn Andersson <andersson@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>