• Alexander Shishkin's avatar
    stm class: Fix a module refcount leak in policy creation error path · c18614a1
    Alexander Shishkin authored
    Commit c7fd62bc ("stm class: Introduce framing protocol drivers")
    adds a bug into the error path of policy creation, that would do a
    module_put() on a wrong module, if one tried to create a policy for
    an stm device which already has a policy, using a different protocol.
    IOW,
    
    | mkdir /config/stp-policy/dummy_stm.0:p_basic.test
    | mkdir /config/stp-policy/dummy_stm.0:p_sys-t.test # puts "p_basic"
    | mkdir /config/stp-policy/dummy_stm.0:p_sys-t.test # "p_basic" -> -1
    
    throws:
    
    | general protection fault: 0000 [#1] SMP PTI
    | CPU: 3 PID: 2887 Comm: mkdir
    | RIP: 0010:module_put.part.31+0xe/0x90
    | Call Trace:
    |  module_put+0x13/0x20
    |  stm_put_protocol+0x11/0x20 [stm_core]
    |  stp_policy_make+0xf1/0x210 [stm_core]
    |  ? __kmalloc+0x183/0x220
    |  ? configfs_mkdir+0x10d/0x4c0
    |  configfs_mkdir+0x169/0x4c0
    |  vfs_mkdir+0x108/0x1c0
    |  do_mkdirat+0xe8/0x110
    |  __x64_sys_mkdir+0x1b/0x20
    |  do_syscall_64+0x5a/0x140
    |  entry_SYSCALL_64_after_hwframe+0x44/0xa9
    
    Correct this sad mistake by calling calling 'put' on the correct
    reference, which happens to match another error path in the same
    function, so we consolidate the two at the same time.
    Signed-off-by: default avatarAlexander Shishkin <alexander.shishkin@linux.intel.com>
    Fixes: c7fd62bc ("stm class: Introduce framing protocol drivers")
    Reported-by: default avatarAmmy Yi <ammy.yi@intel.com>
    Cc: stable <stable@vger.kernel.org>
    Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
    c18614a1
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