iov_iter: fix page_copy_sane for compound pages
Issue is that if the data crosses a page boundary inside a compound
page, this check will incorrectly trigger a WARN_ON.
To fix this, compute the order using the head of the compound page and
adjust the offset to be relative to that head.
Fixes: 72e809ed81
("iov_iter: sanity checks for copy to/from page
primitives")
Signed-off-by: Petar Penkov <ppenkov@google.com>
CC: Al Viro <viro@zeniv.linux.org.uk>
CC: Eric Dumazet <edumazet@google.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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@ -687,8 +687,10 @@ EXPORT_SYMBOL(_copy_from_iter_full_nocache);
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static inline bool page_copy_sane(struct page *page, size_t offset, size_t n)
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static inline bool page_copy_sane(struct page *page, size_t offset, size_t n)
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{
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{
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size_t v = n + offset;
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struct page *head = compound_head(page);
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if (likely(n <= v && v <= (PAGE_SIZE << compound_order(page))))
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size_t v = n + offset + page_address(page) - page_address(head);
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if (likely(n <= v && v <= (PAGE_SIZE << compound_order(head))))
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return true;
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return true;
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WARN_ON(1);
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WARN_ON(1);
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return false;
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return false;
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