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: archive/raspbian/4.9.51-1+rpi1~7^2~145 X-Git-Url: https://dgit.raspbian.org/?a=commitdiff_plain;h=9e0a64330ce5ef4be20391fdf7c95a1d7ac67538;p=linux-4.9.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 28556fce4267..45af0fe00f33 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 && page_ref_count(page)) + put_page(page); + } kfree(sreq->tsg); }