[PATCH next] liveupdate: luo_file: don't use invalid list iterator

[PATCH next] liveupdate: luo_file: don't use invalid list iterator

[Dan Carpenter]

If we exit a list_for_each_entry() without hitting a break then the
list iterator points to an offset from the list_head.  It's a
non-NULL but invalid pointer and dereferencing it isn't allowed.

Introduce a new "found" variable to test instead.

Fixes: 3ee1d673194e ("liveupdate: luo_file: implement file systems callbacks")
Reported-by: kernel test robot <lkp@intel.com>
Closes: https://lore.kernel.org/r/202511280420.y9O4fyhX-lkp@intel.com/
Signed-off-by: Dan Carpenter <dan.carpenter@linaro.org>
---
Presumably, this going to be folded into the original patch.  I just
added the tags because they are harmless.

 kernel/liveupdate/luo_file.c | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/kernel/liveupdate/luo_file.c b/kernel/liveupdate/luo_file.c
index fca3806dae28..86b4d274d9aa 100644
--- a/kernel/liveupdate/luo_file.c
+++ b/kernel/liveupdate/luo_file.c
@@ -561,17 +561,20 @@ int luo_retrieve_file(struct luo_file_set *file_set, u64 token,
 {
 	struct liveupdate_file_op_args args = {0};
 	struct luo_file *luo_file;
+	bool found = false;
 	int err;
 
 	if (list_empty(&file_set->files_list))
 		return -ENOENT;
 
 	list_for_each_entry(luo_file, &file_set->files_list, list) {
-		if (luo_file->token == token)
+		if (luo_file->token == token) {
+			found = true;
 			break;
+		}
 	}
 
-	if (luo_file->token != token)
+	if (!found)
 		return -ENOENT;
 
 	guard(mutex)(&luo_file->mutex);
-- 
2.51.0

Re: [PATCH next] liveupdate: luo_file: don't use invalid list iterator

[Mike Rapoport]

On Fri, Nov 28, 2025 at 10:17:07AM +0300, Dan Carpenter wrote:
> If we exit a list_for_each_entry() without hitting a break then the
> list iterator points to an offset from the list_head.  It's a
> non-NULL but invalid pointer and dereferencing it isn't allowed.
> 
> Introduce a new "found" variable to test instead.
> 
> Fixes: 3ee1d673194e ("liveupdate: luo_file: implement file systems callbacks")
> Reported-by: kernel test robot <lkp@intel.com>
> Closes: https://lore.kernel.org/r/202511280420.y9O4fyhX-lkp@intel.com/
> Signed-off-by: Dan Carpenter <dan.carpenter@linaro.org>

Reviewed-by: Mike Rapoport (Microsoft) <rppt@kernel.org>

> ---
> Presumably, this going to be folded into the original patch.  I just
> added the tags because they are harmless.
> 
>  kernel/liveupdate/luo_file.c | 7 +++++--
>  1 file changed, 5 insertions(+), 2 deletions(-)
> 
> diff --git a/kernel/liveupdate/luo_file.c b/kernel/liveupdate/luo_file.c
> index fca3806dae28..86b4d274d9aa 100644
> --- a/kernel/liveupdate/luo_file.c
> +++ b/kernel/liveupdate/luo_file.c
> @@ -561,17 +561,20 @@ int luo_retrieve_file(struct luo_file_set *file_set, u64 token,
>  {
>  	struct liveupdate_file_op_args args = {0};
>  	struct luo_file *luo_file;
> +	bool found = false;
>  	int err;
>  
>  	if (list_empty(&file_set->files_list))
>  		return -ENOENT;
>  
>  	list_for_each_entry(luo_file, &file_set->files_list, list) {
> -		if (luo_file->token == token)
> +		if (luo_file->token == token) {
> +			found = true;
>  			break;
> +		}
>  	}
>  
> -	if (luo_file->token != token)
> +	if (!found)
>  		return -ENOENT;
>  
>  	guard(mutex)(&luo_file->mutex);
> -- 
> 2.51.0
> 

-- 
Sincerely yours,
Mike.

Re: [PATCH next] liveupdate: luo_file: don't use invalid list iterator

[Pasha Tatashin]

> Fixes: 3ee1d673194e ("liveupdate: luo_file: implement file systems callbacks")
> Reported-by: kernel test robot <lkp@intel.com>
> Closes: https://lore.kernel.org/r/202511280420.y9O4fyhX-lkp@intel.com/
> Signed-off-by: Dan Carpenter <dan.carpenter@linaro.org>

Reviewed-by: Pasha Tatashin <pasha.tatashin@soleen.com>

Thank you,
Pasha

Re: [PATCH next] liveupdate: luo_file: don't use invalid list iterator

[Pasha Tatashin]

On Fri, Nov 28, 2025 at 9:38 AM Pasha Tatashin
<pasha.tatashin@soleen.com> wrote:
>
> > Fixes: 3ee1d673194e ("liveupdate: luo_file: implement file systems callbacks")
> > Reported-by: kernel test robot <lkp@intel.com>
> > Closes: https://lore.kernel.org/r/202511280420.y9O4fyhX-lkp@intel.com/
> > Signed-off-by: Dan Carpenter <dan.carpenter@linaro.org>
>
> Reviewed-by: Pasha Tatashin <pasha.tatashin@soleen.com>

Given that this patch is already in nonmm-stable, it should be OK to
apply this fix in one of the RCs.

>
> Thank you,
> Pasha