Segfault and access to data

Hi,

Here is the dmesg log we get each time of doing mysqldump or simple "SELECT" :

[65080.400295] mysqld[24605]: segfault at a0 ip 00005631c416d13d sp 00007fdb441fd160 error 4 in mysqld[5631c37a1000+1124000]

The data inside the DB has been "freshly imported" a few days ago from a SQL dump. Now the server is on prod but impossible to make a backup or access to some records :

{{MariaDB [otrs2]> select content from article_attachment where id = 32669;

ERROR 2013 (HY000): Lost connection to MySQL server during query

MariaDB [otrs2]> update article_attachment set content = 'xx' where id = 32669;
ERROR 2013 (HY000): Lost connection to MySQL server during query

MariaDB [otrs2]> delete from article_attachment where id = 32669;
ERROR 2013 (HY000): Lost connection to MySQL server during query}}

Tested a lot of parameters. Here is the current ones :

[mysqld]
innodb_file_per_table=1
innodb_log_buffer_size = 32M
innodb_buffer_pool_size = 12G
innodb_log_file_size = 768M
innodb_thread_concurrency = 16
innodb_flush_log_at_trx_commit = 2
innodb_fast_shutdown = 0
max_allowed_packet = 1G
net_read_timeout = 7200
net_write_timeout = 7200
#innodb_force_recovery = 1

Thanks