From: Christophe Leroy christophe.leroy@c-s.fr
commit aeb87246537a83c2aff482f3f34a2e0991e02cbc upstream.
All mapping iterator logic is based on the assumption that sg->offset is always lower than PAGE_SIZE.
But there are situations where sg->offset is such that the SG item is on the second page. In that case sg_copy_to_buffer() fails properly copying the data into the buffer. One of the reason is that the data will be outside the kmapped area used to access that data.
This patch fixes the issue by adjusting the mapping iterator offset and pgoffset fields such that offset is always lower than PAGE_SIZE.
Signed-off-by: Christophe Leroy christophe.leroy@c-s.fr Fixes: 4225fc8555a9 ("lib/scatterlist: use page iterator in the mapping iterator") Cc: stable@vger.kernel.org Signed-off-by: Herbert Xu herbert@gondor.apana.org.au Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- lib/scatterlist.c | 9 +++++---- 1 file changed, 5 insertions(+), 4 deletions(-)
--- a/lib/scatterlist.c +++ b/lib/scatterlist.c @@ -652,17 +652,18 @@ static bool sg_miter_get_next_page(struc { if (!miter->__remaining) { struct scatterlist *sg; - unsigned long pgoffset;
if (!__sg_page_iter_next(&miter->piter)) return false;
sg = miter->piter.sg; - pgoffset = miter->piter.sg_pgoffset;
- miter->__offset = pgoffset ? 0 : sg->offset; + miter->__offset = miter->piter.sg_pgoffset ? 0 : sg->offset; + miter->piter.sg_pgoffset += miter->__offset >> PAGE_SHIFT; + miter->__offset &= PAGE_SIZE - 1; miter->__remaining = sg->offset + sg->length - - (pgoffset << PAGE_SHIFT) - miter->__offset; + (miter->piter.sg_pgoffset << PAGE_SHIFT) - + miter->__offset; miter->__remaining = min_t(unsigned long, miter->__remaining, PAGE_SIZE - miter->__offset); }