Re: [PATCH] Fix error handling in begin_new_exec
From: Eric W. Biederman <hidden>
Date: 2021-06-06 19:35:18
Also in:
lkml
Bernd Edlinger [off-list ref] writes:
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.
Acked-by: "Eric W. Biederman" <redacted> Yuck. I wonder if there is a less error prone idiom we could be using here than testing bprm->cred in free_bprm. Especially as this lock is expected to stay held through setup_new_exec. Something feels too clever here.
quoted hunk
Fixes: b8a61c9e7b4 ("exec: Generic execfd support") Signed-off-by: Bernd Edlinger <redacted> --- fs/exec.c | 3 +++ 1 file changed, 3 insertions(+)diff --git a/fs/exec.c b/fs/exec.c index 18594f1..d8af85f 100644 --- a/fs/exec.c +++ b/fs/exec.c@@ -1396,6 +1396,9 @@ int begin_new_exec(struct linux_binprm * bprm) out_unlock: up_write(&me->signal->exec_update_lock); + if (!bprm->cred) + mutex_unlock(&me->signal->cred_guard_mutex); + out: return retval; }