From: Stephan Mueller Date: Wed, 16 Aug 2017 09:56:24 +0000 (+0200) Subject: crypto: algif_skcipher - only call put_page on referenced and used pages X-Git-Tag: v4.4.87~1 X-Git-Url: http://git.ipfire.org/gitweb.cgi?a=commitdiff_plain;h=d95827490c39d20c148b3c4c3d250f9cce294eb5;p=thirdparty%2Fkernel%2Fstable.git crypto: algif_skcipher - only call put_page on referenced and used pages 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 Signed-off-by: Herbert Xu Signed-off-by: Greg Kroah-Hartman --- diff --git a/crypto/algif_skcipher.c b/crypto/algif_skcipher.c index f5e9f9310b486..b3b0004ea8ac9 100644 --- a/crypto/algif_skcipher.c +++ b/crypto/algif_skcipher.c @@ -86,8 +86,13 @@ static void skcipher_free_async_sgls(struct skcipher_async_req *sreq) } 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 && atomic_read(&page->_count)) + put_page(page); + } kfree(sreq->tsg); }