From 445a582738de6802669aeed9c33ca406c23c3b1f Mon Sep 17 00:00:00 2001 From: Stephan Mueller Date: Wed, 16 Aug 2017 11:56:24 +0200 Subject: [PATCH] crypto: algif_skcipher - only call put_page on referenced and used pages 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. Cc: Signed-off-by: Stephan Mueller Signed-off-by: Herbert Xu --- crypto/algif_skcipher.c | 9 +++++++-- 1 file changed, 7 insertions(+), 2 deletions(-) diff --git a/crypto/algif_skcipher.c b/crypto/algif_skcipher.c index 43839b00fe6c..903605dbc1a5 100644 --- a/crypto/algif_skcipher.c +++ b/crypto/algif_skcipher.c @@ -87,8 +87,13 @@ 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); } -- 2.20.1