Messages in this thread | | | Date | Thu, 16 Aug 2012 14:30:57 -0700 | From | David Daney <> | Subject | Re: on stack dynamic allocations |
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On 08/16/2012 02:20 PM, Kasatkin, Dmitry wrote: > Hello, > > Some places in the code uses variable-size allocation on stack.. > For example from hmac_setkey(): > > struct { > struct shash_desc shash; > char ctx[crypto_shash_descsize(hash)]; > } desc; > > > sparse complains > > CHECK crypto/hmac.c > crypto/hmac.c:57:47: error: bad constant expression > > I like it instead of kmalloc.. > > But what is position of kernel community about it?
If you know that the range of crypto_shash_descsize(hash) is bounded, just use the upper bound.
If the range of crypto_shash_descsize(hash) is unbounded, then the stack will overflow and ... BOOM!
David Daney
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