linux-kernel - possible krealloc with __GFP

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Date:	Thu, 28 Jul 2016 11:11:31 -0700
From:	Joe Perches <joe@...ches.com>
To:	Chris Metcalf <cmetcalf@...era.com>,
	Matt Fleming <matt@...eblueprint.co.uk>,
	Arnd Bergmann <arnd@...db.de>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	Ferruh Yigit <fery@...ress.com>,
	Dmitry Torokhov <dmitry.torokhov@...il.com>,
	Jaroslav Kysela <perex@...ex.cz>, Takashi Iwai <tiwai@...e.com>
Cc:	LKML <linux-kernel@...r.kernel.org>
Subject: possible krealloc with __GFP_ZERO defects

(forwarding to the maintainers of other uses)

On Thu, 2016-07-28 at 10:27 -0700, Joe Perches wrote:
> There is a defect in krealloc with __GFP_ZERO so this code in
> drivers/chat/tile-srom.c may not work properly:
> 
> drivers/char/tile-srom.c-       for (i = 0; ; i++) {
> drivers/char/tile-srom.c-               int devhdl;
> drivers/char/tile-srom.c-               char buf[20];
> drivers/char/tile-srom.c-               struct srom_dev *new_srom_devices =
> drivers/char/tile-srom.c-                       krealloc(srom_devices, (i+1) * sizeof(struct srom_dev),
> drivers/char/tile-srom.c:                                GFP_KERNEL | __GFP_ZERO);
> drivers/char/tile-srom.c-               if (!new_srom_devices) {
> drivers/char/tile-srom.c-                       result = -ENOMEM;
> drivers/char/tile-srom.c-                       goto fail_mem;
> drivers/char/tile-srom.c-               }
> drivers/char/tile-srom.c-               srom_devices = new_srom_devices;
> 
> http://linux-kernel.vger.kernel.narkive.com/xyiQV3vf/slab-krealloc-with-gfp-zero-defect

Here are the other in-tree uses that may not work properly

$ grep-2.5.4 -rP --include=*.[ch] -n "krealloc[^;]+__GFP_ZERO" *
drivers/firmware/efi/capsule-loader.c:87:	temp_page = krealloc(cap_info->pages,
			     pages_needed * sizeof(void *),
			     GFP_KERNEL | __GFP_ZERO);
drivers/char/tile-srom.c:375:			krealloc(srom_devices, (i+1) * sizeof(struct srom_dev),
				 GFP_KERNEL | __GFP_ZERO);
drivers/input/touchscreen/cyttsp4_core.c:521:		p = krealloc(si->btn, si->si_ofs.btn_keys_size,
				GFP_KERNEL|__GFP_ZERO);
drivers/input/touchscreen/cyttsp4_core.c:565:	p = krealloc(si->xy_mode, si->si_ofs.mode_size, GFP_KERNEL|__GFP_ZERO);
drivers/input/touchscreen/cyttsp4_core.c:570:	p = krealloc(si->xy_data, si->si_ofs.data_size, GFP_KERNEL|__GFP_ZERO);
drivers/input/touchscreen/cyttsp4_core.c:575:	p = krealloc(si->btn_rec_data,
			si->si_ofs.btn_rec_size * si->si_ofs.num_btns,
			GFP_KERNEL|__GFP_ZERO);
sound/hda/array.c:28:		nlist = krealloc(array->list, size, GFP_KERNEL | __GFP_ZERO);
sound/core/info.c:342:		char *nbuf = krealloc(buf->buffer, PAGE_ALIGN(next),
				      GFP_KERNEL | __GFP_ZERO);