[PATCH v2 08/10] Avoid double free in startup_inferior

[Kamil Rytarowski]

On 07.09.2020 21:19, Simon Marchi wrote:
> On 2020-09-03 8:29 p.m., Kamil Rytarowski wrote:
>> Do not free the last execd pathname as it will be used in
>> prepare_resume_reply(), after attaching a client side.
> 
> Ok, so this function returns to its caller the last waitstatus.  So indeed we
> want to clean up all the watstatus objects except the last one, which we hand
> over to the caller.
> 
>> gdb/ChangeLog:
>>
>> 	* fork-inferior.c (startup_inferior): Avoid double free.
>> ---
>>  gdb/ChangeLog           | 4 ++++
>>  gdb/nat/fork-inferior.c | 5 ++++-
>>  2 files changed, 8 insertions(+), 1 deletion(-)
>>
>> diff --git a/gdb/ChangeLog b/gdb/ChangeLog
>> index b96e7bf08e8..1013f6a0b3c 100644
>> --- a/gdb/ChangeLog
>> +++ b/gdb/ChangeLog
>> @@ -1,3 +1,7 @@
>> +2020-09-04  Kamil Rytarowski  <n54@gmx.com>
>> +
>> +	* fork-inferior.c (startup_inferior): Avoid double free.
>> +
>>  2020-09-04  Kamil Rytarowski  <n54@gmx.com>
>>
>>  	* netbsd-nat.h (netbsd_nat::qxfer_siginfo): Add.
>> diff --git a/gdb/nat/fork-inferior.c b/gdb/nat/fork-inferior.c
>> index 1185ef8998b..94ab0b9cbc2 100644
>> --- a/gdb/nat/fork-inferior.c
>> +++ b/gdb/nat/fork-inferior.c
>> @@ -526,7 +526,10 @@ startup_inferior (process_stratum_target *proc_target, pid_t pid, int ntraps,
>>
>>  	  case TARGET_WAITKIND_EXECD:
>>  	    /* Handle EXEC signals as if they were SIGTRAP signals.  */
>> -	    xfree (ws.value.execd_pathname);
>> +	    /* Do not free the last execd pathname as it will be used in
>> +	       prepare_resume_reply(), after attaching a client side.  */
> 
> Since this is common code, let's just write it in a gdbserver or gdb agnostic way.
> 
> I'd suggest something like: Free the exec'ed pathname, but only if this isn't the
> waitstatus we are returning to the caller.
> 

Please be more specific how to fix.

> Simon
> 


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