Commit 13f5938d authored by Jérôme Glisse's avatar Jérôme Glisse Committed by Steve French
Browse files

cifs: fix page reference leak with readv/writev 



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: default avatarJérôme Glisse <jglisse@redhat.com>
Cc: Steve French <sfrench@samba.org>
Cc: linux-cifs@vger.kernel.org
Cc: samba-technical@lists.samba.org
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: linux-fsdevel@vger.kernel.org
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Stable <stable@vger.kernel.org>
Signed-off-by: default avatarSteve French <stfrench@microsoft.com>
Reviewed-by: default avatarPavel Shilovsky <pshilov@microsoft.com>
parent 652727bb

fs/cifs/file.c

+1 −14
Original line number Diff line number Diff line
@@ -2877,7 +2877,6 @@ static void collect_uncached_write_data(struct cifs_aio_ctx *ctx) 
	struct cifs_tcon *tcon;

	struct cifs_sb_info *cifs_sb;

	struct dentry *dentry = ctx->cfile->dentry;

	unsigned int i;

	int rc;



	tcon = tlink_tcon(ctx->cfile->tlink);
@@ -2941,10 +2940,6 @@ static void collect_uncached_write_data(struct cifs_aio_ctx *ctx) 
		kref_put(&wdata->refcount, cifs_uncached_writedata_release);

	}



	if (!ctx->direct_io)

		for (i = 0; i < ctx->npages; i++)

			put_page(ctx->bv[i].bv_page);



	cifs_stats_bytes_written(tcon, ctx->total_len);

	set_bit(CIFS_INO_INVALID_MAPPING, &CIFS_I(dentry->d_inode)->flags);
@@ -3582,7 +3577,6 @@ collect_uncached_read_data(struct cifs_aio_ctx *ctx) 
	struct iov_iter *to = &ctx->iter;

	struct cifs_sb_info *cifs_sb;

	struct cifs_tcon *tcon;

	unsigned int i;

	int rc;



	tcon = tlink_tcon(ctx->cfile->tlink);
@@ -3666,15 +3660,8 @@ collect_uncached_read_data(struct cifs_aio_ctx *ctx) 
		kref_put(&rdata->refcount, cifs_uncached_readdata_release);

	}



	if (!ctx->direct_io) {

		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);

		}



	if (!ctx->direct_io)

		ctx->total_len = ctx->len - iov_iter_count(to);

	}



	/* mask nodata case */

	if (rc == -ENODATA)

fs/cifs/misc.c

+22 −1
Original line number Diff line number Diff line
@@ -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);



	/*

	 * 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);

}