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

[Peng Fan]

On Fri, Mar 28, 2025 at 08:14:41AM -0600, Mathieu Poirier wrote:
>On Fri, Mar 28, 2025 at 12:50:12PM +0800, Peng Fan wrote:
>> On Thu, Mar 27, 2025 at 11:46:33AM -0600, Mathieu Poirier wrote:
>> >Hi,
>> >
>> >On Wed, Mar 26, 2025 at 10:02:14AM +0800, Peng Fan (OSS) wrote:
>> >> From: Peng Fan <peng.fan@xxxxxxx>
>> >> 
>> >> 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?
>> 
>> STM32 and i.MX use their own parse_fw implementation which allows no resource
>> table:
>> https://elixir.bootlin.com/linux/v6.13.7/source/drivers/remoteproc/stm32_rproc.c#L272
>> https://elixir.bootlin.com/linux/v6.13.7/source/drivers/remoteproc/imx_rproc.c#L598
>
>Ok, that settles rproc_fw_boot() but there is also rproc_find_loaded_rsc_table()
>that will return NULL if a resource table is not found and preventing the
>memcpy() in rproc_start() from happening:
>
>https://elixir.bootlin.com/linux/v6.14-rc6/source/drivers/remoteproc/remoteproc_core.c#L1288


Sorry, I forgot to mention below code:
loaded_table is a valid pointer for i.MX, see
https://elixir.bootlin.com/linux/v6.14-rc6/source/drivers/remoteproc/imx_rproc.c#L666,

So loaded_table is valid, it is memcpy trigger kernel panic because table_sz is
not zero while cached_table is NULL.
	loaded_table = rproc_find_loaded_rsc_table(rproc, fw);
	if (loaded_table) {
		memcpy(loaded_table, rproc->cached_table, rproc->table_sz);
		rproc->table_ptr = loaded_table;
	}

Thanks,
Peng

>
>> 
>> Thanks,
>> Peng
>> 
>> >
>> >[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@xxxxxxx>
>> >> ---
>> >> 
>> >> 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
>> >> 
>> >
>