Messages in this thread | | | Date | Wed, 23 Nov 2011 17:50:20 +0300 | From | Dan Carpenter <> | Subject | Re: [PATCH] comedi: integer overflow in do_insnlist_ioctl() |
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On Wed, Nov 23, 2011 at 08:59:52AM -0500, Xi Wang wrote: > Thanks for the pointer. However you cannot do the overflow check using > > if (sizeof(struct comedi_insn) * insnlist.n_insns < insnlist.n_insns) > > Let's assume 32-bit system, sizeof(struct comedi_insn) = 32, and > insnlist.n_insns = 0x7fffffff. > > Note that 32 * 0x7fffffff = 0xffffffe0 overflows but bypasses your check. >
Argh... You're right, my check is wrong. What I like about my patch though is that it doesn't introduce an arbitrary limit. Could you redo your check without the MAX_INSNS?
regards, dan carpenter
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