[PATCH] staging: erofs: refuse to mount images with malformed volume name

[PATCH] staging: erofs: refuse to mount images with malformed volume name

[Gao Xiang]

From: Gao Xiang <gaoxiang25@huawei.com>

As Richard reminder [1], A valid volume name should be
ended in NIL terminator within the length of volume_name.

Since this field currently isn't really used, let's fix
it to avoid potential bugs in the future.

[1] https://lore.kernel.org/r/1133002215.69049.1566119033047.JavaMail.zimbra@nod.at/

Reported-by: Richard Weinberger <richard@nod.at>
Signed-off-by: Gao Xiang <gaoxiang25@huawei.com>
---
 drivers/staging/erofs/super.c | 9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)

diff --git a/drivers/staging/erofs/super.c b/drivers/staging/erofs/super.c
index f65a1ff9f42f..2da471010a86 100644
--- a/drivers/staging/erofs/super.c
+++ b/drivers/staging/erofs/super.c
@@ -131,9 +131,14 @@ static int superblock_read(struct super_block *sb)
 	sbi->build_time_nsec = le32_to_cpu(layout->build_time_nsec);
 
 	memcpy(&sb->s_uuid, layout->uuid, sizeof(layout->uuid));
-	memcpy(sbi->volume_name, layout->volume_name,
-	       sizeof(layout->volume_name));
 
+	ret = strscpy(sbi->volume_name, layout->volume_name,
+		      sizeof(layout->volume_name));
+	if (ret < 0) {	/* -E2BIG */
+		errln("bad volume name without NIL terminator");
+		ret = -EFSCORRUPTED;
+		goto out;
+	}
 	ret = 0;
 out:
 	brelse(bh);
-- 
2.17.1

Re: [PATCH] staging: erofs: refuse to mount images with malformed volume name

[kbuild test robot]

[-- Attachment #1: Type: text/plain, Size: 2134 bytes --]

Hi Gao,

I love your patch! Yet something to improve:

[auto build test ERROR on linus/master]
[cannot apply to v5.3-rc4 next-20190816]
[if your patch is applied to the wrong git tree, please drop us a note to help improve the system]

url:    https://github.com/0day-ci/linux/commits/Gao-Xiang/staging-erofs-refuse-to-mount-images-with-malformed-volume-name/20190818-193037
config: sparc64-allmodconfig (attached as .config)
compiler: sparc64-linux-gcc (GCC) 7.4.0
reproduce:
        wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
        chmod +x ~/bin/make.cross
        # save the attached .config to linux build tree
        GCC_VERSION=7.4.0 make.cross ARCH=sparc64 

If you fix the issue, kindly add following tag
Reported-by: kbuild test robot <lkp@intel.com>

All errors (new ones prefixed by >>):

   drivers/staging/erofs/super.c: In function 'superblock_read':
>> drivers/staging/erofs/super.c:153:10: error: 'EFSCORRUPTED' undeclared (first use in this function); did you mean 'FS_NRSUPER'?
      ret = -EFSCORRUPTED;
             ^~~~~~~~~~~~
             FS_NRSUPER
   drivers/staging/erofs/super.c:153:10: note: each undeclared identifier is reported only once for each function it appears in

vim +153 drivers/staging/erofs/super.c

   140	
   141		sbi->root_nid = le16_to_cpu(layout->root_nid);
   142		sbi->inos = le64_to_cpu(layout->inos);
   143	
   144		sbi->build_time = le64_to_cpu(layout->build_time);
   145		sbi->build_time_nsec = le32_to_cpu(layout->build_time_nsec);
   146	
   147		memcpy(&sb->s_uuid, layout->uuid, sizeof(layout->uuid));
   148	
   149		ret = strscpy(sbi->volume_name, layout->volume_name,
   150			      sizeof(layout->volume_name));
   151		if (ret < 0) {	/* -E2BIG */
   152			errln("bad volume name without NIL terminator");
 > 153			ret = -EFSCORRUPTED;
   154			goto out;
   155		}
   156		ret = 0;
   157	out:
   158		brelse(bh);
   159		return ret;
   160	}
   161	

---
0-DAY kernel test infrastructure                Open Source Technology Center
https://lists.01.org/pipermail/kbuild-all                   Intel Corporation

[-- Attachment #2: .config.gz --]
[-- Type: application/gzip, Size: 58668 bytes --]

Re: [PATCH] staging: erofs: refuse to mount images with malformed volume name

[Chao Yu]

On 2019-8-18 18:28, Gao Xiang wrote:
> From: Gao Xiang <gaoxiang25@huawei.com>
> 
> As Richard reminder [1], A valid volume name should be
> ended in NIL terminator within the length of volume_name.
> 
> Since this field currently isn't really used, let's fix
> it to avoid potential bugs in the future.
> 
> [1] https://lore.kernel.org/r/1133002215.69049.1566119033047.JavaMail.zimbra@nod.at/
> 
> Reported-by: Richard Weinberger <richard@nod.at>
> Signed-off-by: Gao Xiang <gaoxiang25@huawei.com>

Reviewed-by: Chao Yu <yuchao0@huawei.com>

Thanks,