Messages in this thread | | | Date | Mon, 28 Jul 2014 19:32:11 +0800 | From | "xinhui.pan" <> | Subject | Re: [PATCH] tty/n_gsm.c: fix a memory leak in gsmld_open |
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于 2014年07月28日 17:03, xinhui.pan 写道: > Hi, Jiri > > 于 2014年07月28日 16:49, Jiri Slaby 写道: >> On 07/28/2014 10:14 AM, xinhui.pan wrote: >>> If gsmld_attach_gsm fails, the gsm is not used anymore. >>> tty core will not call gsmld_close to do the cleanup work. >>> tty core just restore to the tty old ldisc. >>> That always causes memory leak. >> >> Nice catch! >> >>> --- a/drivers/tty/n_gsm.c >>> +++ b/drivers/tty/n_gsm.c >>> @@ -2382,7 +2383,13 @@ static int gsmld_open(struct tty_struct *tty) >>> >>> /* Attach the initial passive connection */ >>> gsm->encoding = 1; >>> - return gsmld_attach_gsm(tty, gsm); >>> + >>> + ret = gsmld_attach_gsm(tty, gsm); >>> + if (ret != 0) { >>> + gsm_cleanup_mux(gsm); >>> + mux_put(gsm); >> >> It is quite illogical to put the mux here. It should be in gsmld_open. >> I.e. gsm_cleanup_mux here, mux_put there. >> > > Thanks for your reply :) > But I am a little confused with your comments, could you explain it when you are free? > Sorry for my poor English. >
hi, Jiri I guess you want gsm_cleanup_mux() called in gsmld_attach_gsm(), just after gsm_activate_mux() fails? Yes, that seems really make sence. :) Thanks for pointing out it.
Let me explain my opinion. :) Actually gsmld_attach_gsm results in two different effects when it fails. (a)gsmld_attach_gsm -> gsm_activate_mux(gsm_mux[] is full,-EBUSY), then gsm_mux[] did not change, and gsm->num is invaild; (b)gsmld_attach_gsm -> gsm_activate_mux(return -ENOMEM), then gsm_mux[] changes, and gsm->num is vaild.
To be honest, I am not very clear about this. I even suspect this is done in such way on purpose. So I just keep the code what it is now. Let's handle the error in gsmld_open(). We can make sure that gsm is not used here and it's safe to cleanup and put it.
thanks,
xinhui
> thanks, > > xinhui > >> thanks, >> -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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