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[ Upstream commita4ae32c71f] An invariant of cap_bprm_set_creds is that every field in the new cred structure that cap_bprm_set_creds might set, needs to be set every time to ensure the fields does not get a stale value. The field cap_ambient is not set every time cap_bprm_set_creds is called, which means that if there is a suid or sgid script with an interpreter that has neither the suid nor the sgid bits set the interpreter should be able to accept ambient credentials. Unfortuantely because cap_ambient is not reset to it's original value the interpreter can not accept ambient credentials. Given that the ambient capability set is expected to be controlled by the caller, I don't think this is particularly serious. But it is definitely worth fixing so the code works correctly. I have tested to verify my reading of the code is correct and the interpreter of a sgid can receive ambient capabilities with this change and cannot receive ambient capabilities without this change. Cc: stable@vger.kernel.org Cc: Andy Lutomirski <luto@kernel.org> Fixes:58319057b7("capabilities: ambient capabilities") Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com> Signed-off-by: Sasha Levin <sashal@kernel.org>