4.9-stable review patch. If anyone has any objections, please let me know. ------------------ From: Stephan Mueller <smueller@xxxxxxxxxx> commit 445a582738de6802669aeed9c33ca406c23c3b1f upstream. For asynchronous operation, SGs are allocated without a page mapped to them or with a page that is not used (ref-counted). If the SGL is freed, the code must only call put_page for an SG if there was a page assigned and ref-counted in the first place. This fixes a kernel crash when using io_submit with more than one iocb using the sendmsg and sendpage (vmsplice/splice) interface. Signed-off-by: Stephan Mueller <smueller@xxxxxxxxxx> Signed-off-by: Herbert Xu <herbert@xxxxxxxxxxxxxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- crypto/algif_skcipher.c | 9 +++++++-- 1 file changed, 7 insertions(+), 2 deletions(-) --- a/crypto/algif_skcipher.c +++ b/crypto/algif_skcipher.c @@ -86,8 +86,13 @@ static void skcipher_free_async_sgls(str } sgl = sreq->tsg; n = sg_nents(sgl); - for_each_sg(sgl, sg, n, i) - put_page(sg_page(sg)); + for_each_sg(sgl, sg, n, i) { + struct page *page = sg_page(sg); + + /* some SGs may not have a page mapped */ + if (page && page_ref_count(page)) + put_page(page); + } kfree(sreq->tsg); }