Messages in this thread | | | Date | Fri, 2 Aug 2013 12:00:44 +0100 | From | Rupesh Gujare <> | Subject | Re: [PATCH 5/6] staging: ozwpan: Increase farewell report size. |
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On 02/08/13 11:27, Dan Carpenter wrote: > On Thu, Aug 01, 2013 at 06:45:01PM +0100, Rupesh Gujare wrote: >> Farewell report size can be bigger than one byte, increase array >> size to accomodate maximum 32 bytes of farewell report. >> > Gar... No. This is not right. > > 1) There is no check limiting the size to 32 and it could be up to > 253 bytes. > > 2) Use defines instead of magic numbers. > > 3) The oz_farewell struct is supposed to be a variable length struct > but the variable part is put in the middle. It doesn't make any > sense to put the length of the variable size array after then end > of the array because we can never find it again! Put the > variable size array at the end. Make it a zero length array. > u8 len; > u8 report[0]; > > 4) In oz_add_farewell() we do this: > > f = kmalloc(sizeof(struct oz_farewell) + len - 1, GFP_ATOMIC); > > The "- 1" refers to sizeof(f->report) but because it was a magic > number then it was missed when the sizeof(f->report) changed. > > 5) In [patch 6/6] we set the ->len member. But because it is at the > end of a variable length array with no limit check the remote > attacker can just rewrite it using the memcpy() on the next line. > > Thanks Dan.
A patch follows to fix above issues.
-- Regards, Rupesh Gujare
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