Re: [PATCH V2] remoteproc: core: Clear table_sz when rproc_shutdown

[Mathieu Poirier <mathieu.poirier@linaro.org>]

Hi,

On Wed, Mar 26, 2025 at 10:02:14AM +0800, Peng Fan (OSS) wrote:
> From: Peng Fan <peng.fan@nxp.com>
> 
> 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.
>

If a firwmare image doesn't have a resouce table, rproc_elf_load_rsc_table()
will return an error [1], rproc_fw_boot() will exit prematurely [2] and the
remote processor won't be started.  What am I missing?

[1]. https://elixir.bootlin.com/linux/v6.14-rc6/source/drivers/remoteproc/remoteproc_elf_loader.c#L338
[2]. https://elixir.bootlin.com/linux/v6.14-rc6/source/drivers/remoteproc/remoteproc_core.c#L1411 

> 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.
> 
> While at here, also clear rproc->table_sz when rproc_fw_boot and
> rproc_detach.
> 
> Fixes: 9dc9507f1880 ("remoteproc: Properly deal with the resource table when detaching")
> Signed-off-by: Peng Fan <peng.fan@nxp.com>
> ---
> 
> V2:
>  Clear table_sz when rproc_fw_boot and rproc_detach per Arnaud
> 
>  drivers/remoteproc/remoteproc_core.c | 3 +++
>  1 file changed, 3 insertions(+)
> 
> diff --git a/drivers/remoteproc/remoteproc_core.c b/drivers/remoteproc/remoteproc_core.c
> index c2cf0d277729..1efa53d4e0c3 100644
> --- a/drivers/remoteproc/remoteproc_core.c
> +++ b/drivers/remoteproc/remoteproc_core.c
> @@ -1442,6 +1442,7 @@ static int rproc_fw_boot(struct rproc *rproc, const struct firmware *fw)
>  	kfree(rproc->cached_table);
>  	rproc->cached_table = NULL;
>  	rproc->table_ptr = NULL;
> +	rproc->table_sz = 0;
>  unprepare_rproc:
>  	/* release HW resources if needed */
>  	rproc_unprepare_device(rproc);
> @@ -2025,6 +2026,7 @@ int rproc_shutdown(struct rproc *rproc)
>  	kfree(rproc->cached_table);
>  	rproc->cached_table = NULL;
>  	rproc->table_ptr = NULL;
> +	rproc->table_sz = 0;
>  out:
>  	mutex_unlock(&rproc->lock);
>  	return ret;
> @@ -2091,6 +2093,7 @@ int rproc_detach(struct rproc *rproc)
>  	kfree(rproc->cached_table);
>  	rproc->cached_table = NULL;
>  	rproc->table_ptr = NULL;
> +	rproc->table_sz = 0;
>  out:
>  	mutex_unlock(&rproc->lock);
>  	return ret;
> -- 
> 2.37.1
>