6.6-stable review patch. If anyone has any objections, please let me know. ------------------ From: Bernd Edlinger <bernd.edlinger@xxxxxxxxxx> commit 84c39ec57d409e803a9bb6e4e85daf1243e0e80b upstream. If get_unused_fd_flags() fails, the error handling is incomplete because bprm->cred is already set to NULL, and therefore free_bprm will not unlock the cred_guard_mutex. Note there are two error conditions which end up here, one before and one after bprm->cred is cleared. Fixes: b8a61c9e7b4a ("exec: Generic execfd support") Signed-off-by: Bernd Edlinger <bernd.edlinger@xxxxxxxxxx> Acked-by: Eric W. Biederman <ebiederm@xxxxxxxxxxxx> Link: https://lore.kernel.org/r/AS8P193MB128517ADB5EFF29E04389EDAE4752@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx Cc: stable@xxxxxxxxxxxxxxx Signed-off-by: Kees Cook <keescook@xxxxxxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- fs/exec.c | 3 +++ 1 file changed, 3 insertions(+) --- a/fs/exec.c +++ b/fs/exec.c @@ -1410,6 +1410,9 @@ int begin_new_exec(struct linux_binprm * out_unlock: up_write(&me->signal->exec_update_lock); + if (!bprm->cred) + mutex_unlock(&me->signal->cred_guard_mutex); + out: return retval; }