Commit 3df39e0b authored Mar 20, 2024 by Kees Cook Committed by Li Lingfeng Mar 20, 2024

block/rnbd-srv: Check for unlikely string overflow

mainline inclusion
from mainline-v6.8-rc1
commit 9e4bf6a08d1e127bcc4bd72557f2dfafc6bc7f41
category: bugfix
bugzilla: https://gitee.com/src-openeuler/kernel/issues/I99K1F
CVE: CVE-2023-52618

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=9e4bf6a08d1e127bcc4bd72557f2dfafc6bc7f41



--------------------------------

Since "dev_search_path" can technically be as large as PATH_MAX,
there was a risk of truncation when copying it and a second string
into "full_path" since it was also PATH_MAX sized. The W=1 builds were
reporting this warning:

drivers/block/rnbd/rnbd-srv.c: In function 'process_msg_open.isra':
drivers/block/rnbd/rnbd-srv.c:616:51: warning: '%s' directive output may be truncated writing up to 254 bytes into a region of size between 0 and 4095 [-Wformat-truncation=]
  616 |                 snprintf(full_path, PATH_MAX, "%s/%s",
      |                                                   ^~
In function 'rnbd_srv_get_full_path',
    inlined from 'process_msg_open.isra' at drivers/block/rnbd/rnbd-srv.c:721:14: drivers/block/rnbd/rnbd-srv.c:616:17: note: 'snprintf' output between 2 and 4351 bytes into a destination of size 4096
  616 |                 snprintf(full_path, PATH_MAX, "%s/%s",
      |                 ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
  617 |                          dev_search_path, dev_name);
      |                          ~~~~~~~~~~~~~~~~~~~~~~~~~~

To fix this, unconditionally check for truncation (as was already done
for the case where "%SESSNAME%" was present).

Reported-by: kernel test robot <lkp@intel.com>
Closes: https://lore.kernel.org/oe-kbuild-all/202312100355.lHoJPgKy-lkp@intel.com/


Cc: Md. Haris Iqbal <haris.iqbal@ionos.com>
Cc: Jack Wang <jinpu.wang@ionos.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc:  <linux-block@vger.kernel.org>
Signed-off-by: Kees Cook <keescook@chromium.org>
Acked-by: Guoqing Jiang <guoqing.jiang@linux.dev>
Acked-by: Jack Wang <jinpu.wang@ionos.com>
Link: https://lore.kernel.org/r/20231212214738.work.169-kees@kernel.org


Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Li Lingfeng <lilingfeng3@huawei.com>

parent efcbd7d2

drivers/block/rnbd/rnbd-srv.c

+10 −9

Original line number	Diff line number	Diff line
		@@ -591,6 +591,7 @@ static char rnbd_srv_get_full_path(struct rnbd_srv_session srv_sess,
		{
		char *full_path;
		char a, b;
		int len;

		full_path = kmalloc(PATH_MAX, GFP_KERNEL);
		if (!full_path)
		@@ -602,20 +603,20 @@ static char rnbd_srv_get_full_path(struct rnbd_srv_session srv_sess,
		*/
		a = strnstr(dev_search_path, "%SESSNAME%", sizeof(dev_search_path));
		if (a) {
		int len = a - dev_search_path;
		len = a - dev_search_path;

		len = snprintf(full_path, PATH_MAX, "%.*s/%s/%s", len,
		dev_search_path, srv_sess->sessname, dev_name);
		} else {
		len = snprintf(full_path, PATH_MAX, "%s/%s",
		dev_search_path, dev_name);
		}
		if (len >= PATH_MAX) {
		pr_err("Too long path: %s, %s, %s\n",
		dev_search_path, srv_sess->sessname, dev_name);
		kfree(full_path);
		return ERR_PTR(-EINVAL);
		}
		} else {
		snprintf(full_path, PATH_MAX, "%s/%s",
		dev_search_path, dev_name);
		}

		/* eliminitate duplicated slashes */
		a = strchr(full_path, '/');