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SubjectRe: [PATCH v2] fs: add NULL check in drop_buffers() to prevent null-ptr-deref
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On Mon, 8 Dec 2025 11:30:24 -0800, Darrick J. Wong wrote:
> > drop_buffers() dereferences the buffer_head pointer returned by
> > folio_buffers() without checking for NULL. This leads to a null pointer
> > dereference when called from try_to_free_buffers() on a folio with no
> > buffers attached. This happens when filemap_release_folio() is called on
> > a folio belonging to a mapping with AS_RELEASE_ALWAYS set but without
> > release_folio address_space operation defined. In such case,

> What user is that? All the users of AS_RELEASE_ALWAYS in 6.18 appear to
> supply a ->release_folio. Is this some new thing in 6.19?

AFS directories SET AS_RELEASE_ALWAYS but have not .release_folio.


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