From 13f5938d8264b5501368523c4513ff26608a33e8 Mon Sep 17 00:00:00 2001 From: Jérôme Glisse Date: Wed, 10 Apr 2019 15:37:47 -0400 Subject: cifs: fix page reference leak with readv/writev MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit CIFS can leak pages reference gotten through GUP (get_user_pages*() through iov_iter_get_pages()). This happen if cifs_send_async_read() or cifs_write_from_iter() calls fail from within __cifs_readv() and __cifs_writev() respectively. This patch move page unreference to cifs_aio_ctx_release() which will happens on all code paths this is all simpler to follow for correctness. Signed-off-by: Jérôme Glisse Cc: Steve French Cc: linux-cifs@vger.kernel.org Cc: samba-technical@lists.samba.org Cc: Alexander Viro Cc: linux-fsdevel@vger.kernel.org Cc: Linus Torvalds Cc: Stable Signed-off-by: Steve French Reviewed-by: Pavel Shilovsky --- fs/cifs/misc.c | 23 ++++++++++++++++++++++- 1 file changed, 22 insertions(+), 1 deletion(-) (limited to 'fs/cifs/misc.c') diff --git a/fs/cifs/misc.c b/fs/cifs/misc.c index 1e1626a2cfc3..0dc6f08020ac 100644 --- a/fs/cifs/misc.c +++ b/fs/cifs/misc.c @@ -789,6 +789,11 @@ cifs_aio_ctx_alloc(void) { struct cifs_aio_ctx *ctx; + /* + * Must use kzalloc to initialize ctx->bv to NULL and ctx->direct_io + * to false so that we know when we have to unreference pages within + * cifs_aio_ctx_release() + */ ctx = kzalloc(sizeof(struct cifs_aio_ctx), GFP_KERNEL); if (!ctx) return NULL; @@ -807,7 +812,23 @@ cifs_aio_ctx_release(struct kref *refcount) struct cifs_aio_ctx, refcount); cifsFileInfo_put(ctx->cfile); - kvfree(ctx->bv); + + /* + * ctx->bv is only set if setup_aio_ctx_iter() was call successfuly + * which means that iov_iter_get_pages() was a success and thus that + * we have taken reference on pages. + */ + if (ctx->bv) { + unsigned i; + + for (i = 0; i < ctx->npages; i++) { + if (ctx->should_dirty) + set_page_dirty(ctx->bv[i].bv_page); + put_page(ctx->bv[i].bv_page); + } + kvfree(ctx->bv); + } + kfree(ctx); } -- cgit v1.2.3-59-g8ed1b