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    SubjectRe: [PATCH] kmod: prevent kmod_loop_msg overflow in __request_module()
    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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