APPLIED: [PATCH 0/1][f/j/k linux-aws] AWS: RDMA Back port DMA buffer fix

[Tim Gardner]

On 2/3/23 12:43 PM, Tim Gardner wrote:
> https://bugs.launchpad.net/bugs/2004807
> 
> SRU Justification
> 
> [Impact]
> 
> When registering a new DMA MR after selecting the best aligned page size
> for it, we iterate over the given sglist to split each entry to smaller,
> aligned to the selected page size, DMA blocks.
> 
> In given circumstances where the sg entry and page size fit certain
> sizes and the sg entry is not aligned to the selected page size, the
> total size of the aligned pages we need to cover the sg entry is >= 4GB.
> Under this circumstances, while iterating page aligned blocks, the
> counter responsible for counting how much we advanced from the start of
> the sg entry is overflowed because its type is u32 and we pass 4GB in
> size. This can lead to an infinite loop inside the iterator function
> because the overflow prevents the counter to be larger
> than the size of the sg entry.
> 
> Fixes: a808273 ("RDMA/verbs: Add a DMA iterator to return aligned contiguous memory blocks")
> 
> [Test Plan]
> 
> AWS tested
> 
> [Where things could go wrong]
> 
> What could possibly go wrong with Remote DMA scatter/gather list errors ?
> 
> [Other Info]
> 
> SF: #00353710
> 
Applied to f/j/k linux-aws. Thanks.

-rtg
-- 
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Tim Gardner
Canonical, Inc