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

Andy Shevchenko
2023-03-22T14:12:06Z

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(-)

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