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;
}
