Messages in this thread | | | Date | Wed, 11 Mar 2015 10:23:10 +0800 | From | Fam Zheng <> | Subject | Re: [PATCH v4 4/9] epoll: Add implementation for epoll_ctl_batch |
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On Tue, 03/10 09:59, Dan Rosenberg wrote: > On 03/09/2015 09:49 PM, Fam Zheng wrote: > > + if (!cmds || ncmds <= 0 || ncmds > EP_MAX_BATCH) > > + return -EINVAL; > > + cmd_size = sizeof(struct epoll_ctl_cmd) * ncmds; > > + /* TODO: optimize for small arguments like select/poll with a stack > > + * allocated buffer */ > > + > > + kcmds = kmalloc(cmd_size, GFP_KERNEL); > > + if (!kcmds) > > + return -ENOMEM; > You probably want to define EP_MAX_BATCH as some sane value much less > than INT_MAX/(sizeof(struct epoll_ctl_cmd)). While this avoids the > integer overflow from before, any user can cause the kernel to kmalloc > up to INT_MAX bytes. Probably not a huge deal because it's freed at the > end of the syscall, but generally not a great idea. >
Yeah, makes sense, any suggested value?
Thanks, Fam
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