[PATCH 4/5] exec: don't retry if request_module() fails

From: Oleg Nesterov
Date: Fri Aug 02 2013 - 15:33:18 EST

A separate one-liner for better documentation.

It doesn't make sense to retry if request_module() fails to exec
/sbin/modprobe, add the addition "request_module() < 0" check.

However, this logic still doesn't look exactly right:

1. It would be better to check "request_module() != 0", the user
space modprobe process should report the correct exit code.
But I didn't dare to add the user-visible change.

2. The whole ENOEXEC logic looks suboptimal. Suppose that we try
to exec a "#!path-to-unsupported-binary" script. In this case
request_module() + "retry" will be done twice: first by the
"depth == 1" code, and then again by the "depth == 0" caller
which doesn't make sense.

3. And note that in the case above bprm->buf was already changed
by load_script()->prepare_binprm(), so this looks even more

Signed-off-by: Oleg Nesterov <oleg@xxxxxxxxxx>
fs/exec.c | 3 ++-
1 files changed, 2 insertions(+), 1 deletions(-)

diff --git a/fs/exec.c b/fs/exec.c
index 48344a2..d9fd32c 100644
--- a/fs/exec.c
+++ b/fs/exec.c
@@ -1418,7 +1418,8 @@ int search_binary_handler(struct linux_binprm *bprm)
if (printable(bprm->buf[0]) && printable(bprm->buf[1]) &&
printable(bprm->buf[2]) && printable(bprm->buf[3]))
return retval;
- request_module("binfmt-%04x", *(ushort *)(bprm->buf + 2));
+ if (request_module("binfmt-%04x", *(ushort *)(bprm->buf + 2)) < 0)
+ return retval;
need_retry = false;
goto retry;

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