Re: [PATCH] signal: avoid shared siginfo namespace rewrites

[Bradley Morgan]

On June 26, 2026 3:29:07 PM GMT+01:00, Oleg Nesterov <oleg@xxxxxxxxxx>
wrote:
>To avoid the confusion, let me reply to V1 again.
>
>Acked-by: Oleg Nesterov <oleg@xxxxxxxxxx>
>
>IIUC Eric is fine with this change too.
>
>Andrew, can you take this fix please? We will send more changes on top
>of it.

Thanks again oleg.

Andrew did reply to V2. 

>On 06/22, Bradley Morgan wrote:
>>
>> send_signal_locked() rewrites sender ids for the target namespace.
>> Group sends reuse the same siginfo, so one recipient can affect the
>> next.
>> 
>> Copy the siginfo before changing it.
>> 
>> Fixes: 7a0cf094944e ("signal: Correct namespace fixups of si_pid and
>si_uid")
>> Cc: stable@xxxxxxxxxxxxxxx
>> Signed-off-by: Bradley Morgan <include@xxxxxxxxx>
>> ---
>>  kernel/signal.c | 4 ++++
>>  1 file changed, 4 insertions(+)
>> 
>> diff --git a/kernel/signal.c b/kernel/signal.c
>> index b9fc7be1a169..d72d9be3a992 100644
>> --- a/kernel/signal.c
>> +++ b/kernel/signal.c
>> @@ -1181,6 +1181,7 @@ static inline bool has_si_pid_and_uid(struct
>kernel_siginfo *info)
>>  int send_signal_locked(int sig, struct kernel_siginfo *info,
>>  		       struct task_struct *t, enum pid_type type)
>>  {
>> +	struct kernel_siginfo rewritten;
>>  	/* Should SIGKILL or SIGSTOP be received by a pid namespace init? */
>>  	bool force = false;
>>  
>> @@ -1194,6 +1195,9 @@ int send_signal_locked(int sig, struct
>kernel_siginfo *info,
>>  		/* SIGKILL and SIGSTOP is special or has ids */
>>  		struct user_namespace *t_user_ns;
>>  
>> +		rewritten = *info;
>> +		info = &rewritten;
>> +
>>  		rcu_read_lock();
>>  		t_user_ns = task_cred_xxx(t, user_ns);
>>  		if (current_user_ns() != t_user_ns) {
>> -- 
>> 2.53.0
>> 
>
>

Thanks!