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SubjectRe: [PATCH][RFC] Check poll_select_set_timeout return value in sys_poll
On Mon, 24 Jan 2011, Jesper Juhl wrote:

> poll_select_set_timeout() may return -EINVAL if it's given invalid
> arguments. In sys_poll() we don't check the return value. The way
> poll_select_set_timeout() is called here currently I don't think can ever
> actually fail, but it doesn't hurt to be defensive - code has a tendency
> to change over time. This patch checks the return value and returns
> -EINVAL just like we do elsewhere if it does fail.
>
> What do you think? Is this just pointless overhead or actually worth it as
> an "insurance policy"?
>

I guess that if we do this we should at least mark this branch as
unlikely().

Signed-off-by: Jesper Juhl <jj@chaosbits.net>
---
select.c | 5 +++--
1 file changed, 3 insertions(+), 2 deletions(-)
diff --git a/fs/select.c b/fs/select.c
index e56560d..ebdca6e 100644
--- a/fs/select.c
+++ b/fs/select.c
@@ -922,8 +922,9 @@ SYSCALL_DEFINE3(poll, struct pollfd __user *, ufds, unsigned int, nfds,

if (timeout_msecs >= 0) {
to = &end_time;
- poll_select_set_timeout(to, timeout_msecs / MSEC_PER_SEC,
- NSEC_PER_MSEC * (timeout_msecs % MSEC_PER_SEC));
+ if (unlikely(poll_select_set_timeout(to, timeout_msecs / MSEC_PER_SEC,
+ NSEC_PER_MSEC * (timeout_msecs % MSEC_PER_SEC))))
+ return -EINVAL;
}

ret = do_sys_poll(ufds, nfds, to);

--
Jesper Juhl <jj@chaosbits.net> http://www.chaosbits.net/
Don't top-post http://www.catb.org/~esr/jargon/html/T/top-post.html
Plain text mails only, please.



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