diff mbox series

[v1,1/3] jbd2: Avoid printing out the boundary

Message ID	20230322141206.56347-2-andriy.shevchenko@linux.intel.com
State	New
Headers	Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20; From: Andy Shevchenko <andriy.shevchenko@linux.intel.com> To: Kees Cook <keescook@chromium.org>, Greg Kroah-Hartman <gregkh@linuxfoundation.org>, Andy Shevchenko <andriy.shevchenko@linux.intel.com>, Cezary Rojewski <cezary.rojewski@intel.com>, linux-ext4@vger.kernel.org, linux-kernel@vger.kernel.org Cc: "Theodore Ts'o" <tytso@mit.edu>, Jan Kara <jack@suse.com>, Andy Shevchenko <andy@kernel.org>, "Rafael J. Wysocki" <rafael@kernel.org> Subject: [PATCH v1 1/3] jbd2: Avoid printing out the boundary Date: Wed, 22 Mar 2023 16:12:04 +0200 Message-Id: <20230322141206.56347-2-andriy.shevchenko@linux.intel.com> In-Reply-To: <20230322141206.56347-1-andriy.shevchenko@linux.intel.com> References: <20230322141206.56347-1-andriy.shevchenko@linux.intel.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk
Series	lib/string_helpers et al.: Change return value of strreplace() \| [v1,0/3] lib/string_helpers et al.: Change return value of strreplace() [v1,1/3] jbd2: Avoid printing out the boundary [v1,2/3] lib/string_helpers: Change returned value of the strreplace() [v1,3/3] kobject: Use return value of strreplace()

Commit Message

Andy Shevchenko March 22, 2023, 2:12 p.m. UTC

  Theoretically possible that "%pg" will take all room for the j_devname
and hence the "-%lu" will go out the boundary due to unconditional
sprintf() in use. To make this code more robust, replace two sequential
s*printf():s by a single call and then replace forbidden character.
It's possible to do this way, because '/' won't ever be in the result
of "-%lu".

Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
---
 fs/jbd2/journal.c | 5 ++---
 1 file changed, 2 insertions(+), 3 deletions(-)

Comments

kernel test robot March 22, 2023, 4:45 p.m. UTC | #1

Hi Andy,

I love your patch! Perhaps something to improve:

[auto build test WARNING on driver-core/driver-core-testing]
[also build test WARNING on driver-core/driver-core-next driver-core/driver-core-linus kees/for-next/pstore kees/for-next/kspp tytso-ext4/dev linus/master v6.3-rc3 next-20230322]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch#_base_tree_information]

url:    https://github.com/intel-lab-lkp/linux/commits/Andy-Shevchenko/jbd2-Avoid-printing-out-the-boundary/20230322-221425
patch link:    https://lore.kernel.org/r/20230322141206.56347-2-andriy.shevchenko%40linux.intel.com
patch subject: [PATCH v1 1/3] jbd2: Avoid printing out the boundary
config: x86_64-kexec (https://download.01.org/0day-ci/archive/20230323/202303230045.2JeedPWH-lkp@intel.com/config)
compiler: gcc-11 (Debian 11.3.0-8) 11.3.0
reproduce (this is a W=1 build):
        # https://github.com/intel-lab-lkp/linux/commit/6154f5a987ef2ce0084db0eb245d2c3bcde2a02a
        git remote add linux-review https://github.com/intel-lab-lkp/linux
        git fetch --no-tags linux-review Andy-Shevchenko/jbd2-Avoid-printing-out-the-boundary/20230322-221425
        git checkout 6154f5a987ef2ce0084db0eb245d2c3bcde2a02a
        # save the config file
        mkdir build_dir && cp config build_dir/.config
        make W=1 O=build_dir ARCH=x86_64 olddefconfig
        make W=1 O=build_dir ARCH=x86_64 SHELL=/bin/bash fs/jbd2/

If you fix the issue, kindly add following tag where applicable
| Reported-by: kernel test robot <lkp@intel.com>
| Link: https://lore.kernel.org/oe-kbuild-all/202303230045.2JeedPWH-lkp@intel.com/

All warnings (new ones prefixed by >>):

   fs/jbd2/journal.c: In function 'jbd2_journal_init_inode':
>> fs/jbd2/journal.c:1491:15: warning: unused variable 'p' [-Wunused-variable]
    1491 |         char *p;
         |               ^


vim +/p +1491 fs/jbd2/journal.c

470decc613ab20 Dave Kleikamp     2006-10-11  1478  
470decc613ab20 Dave Kleikamp     2006-10-11  1479  /**
f7f4bccb729844 Mingming Cao      2006-10-11  1480   *  journal_t * jbd2_journal_init_inode () - creates a journal which maps to a inode.
470decc613ab20 Dave Kleikamp     2006-10-11  1481   *  @inode: An inode to create the journal in
470decc613ab20 Dave Kleikamp     2006-10-11  1482   *
f7f4bccb729844 Mingming Cao      2006-10-11  1483   * jbd2_journal_init_inode creates a journal which maps an on-disk inode as
470decc613ab20 Dave Kleikamp     2006-10-11  1484   * the journal.  The inode must exist already, must support bmap() and
470decc613ab20 Dave Kleikamp     2006-10-11  1485   * must have all data blocks preallocated.
470decc613ab20 Dave Kleikamp     2006-10-11  1486   */
f7f4bccb729844 Mingming Cao      2006-10-11  1487  journal_t *jbd2_journal_init_inode(struct inode *inode)
470decc613ab20 Dave Kleikamp     2006-10-11  1488  {
f0c9fd5458bacf Geliang Tang      2016-09-15  1489  	journal_t *journal;
30460e1ea3e62f Carlos Maiolino   2020-01-09  1490  	sector_t blocknr;
05496769e5da83 Theodore Ts'o     2008-09-16 @1491  	char *p;
30460e1ea3e62f Carlos Maiolino   2020-01-09  1492  	int err = 0;
30460e1ea3e62f Carlos Maiolino   2020-01-09  1493  
30460e1ea3e62f Carlos Maiolino   2020-01-09  1494  	blocknr = 0;
30460e1ea3e62f Carlos Maiolino   2020-01-09  1495  	err = bmap(inode, &blocknr);
470decc613ab20 Dave Kleikamp     2006-10-11  1496  
30460e1ea3e62f Carlos Maiolino   2020-01-09  1497  	if (err || !blocknr) {
f0c9fd5458bacf Geliang Tang      2016-09-15  1498  		pr_err("%s: Cannot locate journal superblock\n",
f0c9fd5458bacf Geliang Tang      2016-09-15  1499  			__func__);
f0c9fd5458bacf Geliang Tang      2016-09-15  1500  		return NULL;
f0c9fd5458bacf Geliang Tang      2016-09-15  1501  	}
f0c9fd5458bacf Geliang Tang      2016-09-15  1502  
cb3b3bf22cf337 Jan Kara          2022-06-08  1503  	jbd2_debug(1, "JBD2: inode %s/%ld, size %lld, bits %d, blksize %ld\n",
f0c9fd5458bacf Geliang Tang      2016-09-15  1504  		  inode->i_sb->s_id, inode->i_ino, (long long) inode->i_size,
f0c9fd5458bacf Geliang Tang      2016-09-15  1505  		  inode->i_sb->s_blocksize_bits, inode->i_sb->s_blocksize);
f0c9fd5458bacf Geliang Tang      2016-09-15  1506  
f0c9fd5458bacf Geliang Tang      2016-09-15  1507  	journal = journal_init_common(inode->i_sb->s_bdev, inode->i_sb->s_bdev,
f0c9fd5458bacf Geliang Tang      2016-09-15  1508  			blocknr, inode->i_size >> inode->i_sb->s_blocksize_bits,
f0c9fd5458bacf Geliang Tang      2016-09-15  1509  			inode->i_sb->s_blocksize);
470decc613ab20 Dave Kleikamp     2006-10-11  1510  	if (!journal)
470decc613ab20 Dave Kleikamp     2006-10-11  1511  		return NULL;
470decc613ab20 Dave Kleikamp     2006-10-11  1512  
470decc613ab20 Dave Kleikamp     2006-10-11  1513  	journal->j_inode = inode;
900d156bac2bc4 Christoph Hellwig 2022-07-13  1514  	snprintf(journal->j_devname, sizeof(journal->j_devname),
6154f5a987ef2c Andy Shevchenko   2023-03-22  1515  		 "%pg-%lu", journal->j_dev, journal->j_inode->i_ino);
6154f5a987ef2c Andy Shevchenko   2023-03-22  1516  	strreplace(journal->j_devname, '/', '!');
8e85fb3f305b24 Johann Lombardi   2008-01-28  1517  	jbd2_stats_proc_init(journal);
470decc613ab20 Dave Kleikamp     2006-10-11  1518  
470decc613ab20 Dave Kleikamp     2006-10-11  1519  	return journal;
470decc613ab20 Dave Kleikamp     2006-10-11  1520  }
470decc613ab20 Dave Kleikamp     2006-10-11  1521

Jan Kara March 23, 2023, 9:53 a.m. UTC | #2

On Wed 22-03-23 16:12:04, Andy Shevchenko wrote:
> Theoretically possible that "%pg" will take all room for the j_devname
> and hence the "-%lu" will go out the boundary due to unconditional
> sprintf() in use. To make this code more robust, replace two sequential
> s*printf():s by a single call and then replace forbidden character.
> It's possible to do this way, because '/' won't ever be in the result
> of "-%lu".
> 
> Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>

Looks good. Feel free to add:

Reviewed-by: Jan Kara <jack@suse.cz>

								Honza

> ---
>  fs/jbd2/journal.c | 5 ++---
>  1 file changed, 2 insertions(+), 3 deletions(-)
> 
> diff --git a/fs/jbd2/journal.c b/fs/jbd2/journal.c
> index 8ae419152ff6..00c0aa4a3a91 100644
> --- a/fs/jbd2/journal.c
> +++ b/fs/jbd2/journal.c
> @@ -1515,9 +1515,8 @@ journal_t *jbd2_journal_init_inode(struct inode *inode)
>  
>  	journal->j_inode = inode;
>  	snprintf(journal->j_devname, sizeof(journal->j_devname),
> -		 "%pg", journal->j_dev);
> -	p = strreplace(journal->j_devname, '/', '!');
> -	sprintf(p, "-%lu", journal->j_inode->i_ino);
> +		 "%pg-%lu", journal->j_dev, journal->j_inode->i_ino);
> +	strreplace(journal->j_devname, '/', '!');
>  	jbd2_stats_proc_init(journal);
>  
>  	return journal;
> -- 
> 2.40.0.1.gaa8946217a0b
>

Andy Shevchenko March 23, 2023, 12:27 p.m. UTC | #3

On Thu, Mar 23, 2023 at 10:53:46AM +0100, Jan Kara wrote:
> On Wed 22-03-23 16:12:04, Andy Shevchenko wrote:
> > Theoretically possible that "%pg" will take all room for the j_devname
> > and hence the "-%lu" will go out the boundary due to unconditional
> > sprintf() in use. To make this code more robust, replace two sequential
> > s*printf():s by a single call and then replace forbidden character.
> > It's possible to do this way, because '/' won't ever be in the result
> > of "-%lu".
> > 
> > Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
> 
> Looks good. Feel free to add:
> 
> Reviewed-by: Jan Kara <jack@suse.cz>

Thank you! I'll incorporate this into v2 with dropping not anymore used
variable (as found by LKP).

diff mbox series

Patch

diff --git a/fs/jbd2/journal.c b/fs/jbd2/journal.c
index 8ae419152ff6..00c0aa4a3a91 100644
--- a/fs/jbd2/journal.c
+++ b/fs/jbd2/journal.c
@@ -1515,9 +1515,8 @@  journal_t *jbd2_journal_init_inode(struct inode *inode)
 
 	journal->j_inode = inode;
 	snprintf(journal->j_devname, sizeof(journal->j_devname),
-		 "%pg", journal->j_dev);
-	p = strreplace(journal->j_devname, '/', '!');
-	sprintf(p, "-%lu", journal->j_inode->i_ino);
+		 "%pg-%lu", journal->j_dev, journal->j_inode->i_ino);
+	strreplace(journal->j_devname, '/', '!');
 	jbd2_stats_proc_init(journal);
 
 	return journal;