Messages in this thread | | | Date | Thu, 29 Sep 2011 14:31:29 -0700 | From | Andrew Morton <> | Subject | Re: [PATCH] kmod: prevent kmod_loop_msg overflow in __request_module() |
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On Thu, 29 Sep 2011 17:50:45 +0200 (CEST) Jiri Kosina <jkosina@suse.cz> wrote:
> Due to post-decrement
(post-increment)
> in condition of kmod_loop_msg in __request_module(), > the system log can be spammed by much more than 5 instances of the 'runaway > loop' message if the number of events triggering it makes the kmod_loop_msg > to overflow. > > Fix that by making sure we never increment it past the threshold. > > Signed-off-by: Jiri Kosina <jkosina@suse.cz> > --- > kernel/kmod.c | 4 +++- > 1 files changed, 3 insertions(+), 1 deletions(-) > > diff --git a/kernel/kmod.c b/kernel/kmod.c > index ddc7644..a4bea97 100644 > --- a/kernel/kmod.c > +++ b/kernel/kmod.c > @@ -114,10 +114,12 @@ int __request_module(bool wait, const char *fmt, ...) > atomic_inc(&kmod_concurrent); > if (atomic_read(&kmod_concurrent) > max_modprobes) { > /* We may be blaming an innocent here, but unlikely */ > - if (kmod_loop_msg++ < 5) > + if (kmod_loop_msg < 5) { > printk(KERN_ERR > "request_module: runaway loop modprobe %s\n", > module_name); > + kmod_loop_msg++; > + } > atomic_dec(&kmod_concurrent); > return -ENOMEM; > }
Well, it will take two billion passes through here to cause the overflow. I really hope you found this problem by inspection!
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