Messages in this thread |  | | Subject | Re: [PATCH v2 2/2] KVM: s390: Use memdup_user() rather than duplicating code | From | SF Markus Elfring <> | Date | Mon, 3 Oct 2016 15:47:46 +0200 |
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>> Did you notice the check "IS_ERR(bp_data)" and the corresponding reaction >> in this update suggestion? > > Yes, but bp_data may still be a valid (as in "not an error") value.
Thanks for your constructive feedback.
> Your commit a1708a2eaded836b ("KVM: s390: Improve determination of sizes in > kvm_s390_import_bp_data()") made the code more robust, as kmalloc_array() ha > a builtin overflow check, and will return NULL if overflow is detected. > However, commit 0624a8eb82efd58e ("KVM: s390: Use memdup_user() rather than > duplicating code") dropped that safety net again.
* How much are you concerned about the shown software evolution around multiplications for memory allocations?
* Does there really a probability remain that an inappropriate product would be calculated here (as the situation was before my two update steps for this software module)?
* Can it be that you are looking for a variant of a function like "memdup_user" where values can be passed as separate parameters "count" and "size" so that the needed multiplication and corresponding overflow check would be performed together as desired?
Regards, Markus
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