| Message ID | 365628d054c3dde892133225ba1337ec2d28a904.1526926496.git.joseph.salisbury@canonical.com |
|---|---|
| State | New |
| Headers | show |
| Series | iov_iter: fix page_copy_sane for compound pages | expand |
On 06/01/18 09:29, Joseph Salisbury wrote: > From: Petar Penkov <ppenkov@google.com> > > BugLink: http://bugs.launchpad.net/bugs/1772031 > > 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: 72e809ed81ed ("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> > (cherry picked from commit a90bcb86ae700c12432446c4aa1819e7b8e172ec) > Signed-off-by: Joseph Salisbury <joseph.salisbury@canonical.com> Acked-by: Kleber Sacilotto de Souza <kleber.souza@canonical.com> > --- > lib/iov_iter.c | 6 ++++-- > 1 file changed, 4 insertions(+), 2 deletions(-) > > diff --git a/lib/iov_iter.c b/lib/iov_iter.c > index 52c8dd6..1c1c06d 100644 > --- a/lib/iov_iter.c > +++ b/lib/iov_iter.c > @@ -687,8 +687,10 @@ EXPORT_SYMBOL(_copy_from_iter_full_nocache); > > static inline bool page_copy_sane(struct page *page, size_t offset, size_t n) > { > - size_t v = n + offset; > - if (likely(n <= v && v <= (PAGE_SIZE << compound_order(page)))) > + struct page *head = compound_head(page); > + size_t v = n + offset + page_address(page) - page_address(head); > + > + if (likely(n <= v && v <= (PAGE_SIZE << compound_order(head)))) > return true; > WARN_ON(1); > return false; >
diff --git a/lib/iov_iter.c b/lib/iov_iter.c index 52c8dd6..1c1c06d 100644 --- a/lib/iov_iter.c +++ b/lib/iov_iter.c @@ -687,8 +687,10 @@ EXPORT_SYMBOL(_copy_from_iter_full_nocache); static inline bool page_copy_sane(struct page *page, size_t offset, size_t n) { - size_t v = n + offset; - if (likely(n <= v && v <= (PAGE_SIZE << compound_order(page)))) + struct page *head = compound_head(page); + size_t v = n + offset + page_address(page) - page_address(head); + + if (likely(n <= v && v <= (PAGE_SIZE << compound_order(head)))) return true; WARN_ON(1); return false;