[PATCH] jfs: fix out-of-bounds in dbNextAG() and diAlloc()

From: Jeongjun Park
Date: Mon Aug 19 2024 - 00:05:59 EST


In dbNextAG() , there is no check for the case where bmp->db_numag is
greater or same than MAXAG due to a polluted image, which causes an
out-of-bounds. Therefore, a bounds check should be added in dbMount().

And in dbNextAG(), a check for the case where agpref is greater than
bmp->db_numag should be added, so an out-of-bounds exception should be
prevented.

Additionally, a check for the case where agno is greater or same than
MAXAG should be added in diAlloc() to prevent out-of-bounds.

Reported-by: Jeongjun Park <aha310510@xxxxxxxxx>
Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
Signed-off-by: Jeongjun Park <aha310510@xxxxxxxxx>
---
fs/jfs/jfs_dmap.c | 4 ++--
fs/jfs/jfs_imap.c | 2 +-
2 files changed, 3 insertions(+), 3 deletions(-)

diff --git a/fs/jfs/jfs_dmap.c b/fs/jfs/jfs_dmap.c
index 5713994328cb..0625d1c0d064 100644
--- a/fs/jfs/jfs_dmap.c
+++ b/fs/jfs/jfs_dmap.c
@@ -187,7 +187,7 @@ int dbMount(struct inode *ipbmap)
}

bmp->db_numag = le32_to_cpu(dbmp_le->dn_numag);
- if (!bmp->db_numag) {
+ if (!bmp->db_numag || bmp->db_numag >= MAXAG) {
err = -EINVAL;
goto err_release_metapage;
}
@@ -652,7 +652,7 @@ int dbNextAG(struct inode *ipbmap)
* average free space.
*/
for (i = 0 ; i < bmp->db_numag; i++, agpref++) {
- if (agpref == bmp->db_numag)
+ if (agpref >= bmp->db_numag)
agpref = 0;

if (atomic_read(&bmp->db_active[agpref]))
diff --git a/fs/jfs/jfs_imap.c b/fs/jfs/jfs_imap.c
index 1407feccbc2d..a360b24ed320 100644
--- a/fs/jfs/jfs_imap.c
+++ b/fs/jfs/jfs_imap.c
@@ -1360,7 +1360,7 @@ int diAlloc(struct inode *pip, bool dir, struct inode *ip)
/* get the ag number of this iag */
agno = BLKTOAG(JFS_IP(pip)->agstart, JFS_SBI(pip->i_sb));
dn_numag = JFS_SBI(pip->i_sb)->bmap->db_numag;
- if (agno < 0 || agno > dn_numag)
+ if (agno < 0 || agno > dn_numag || agno >= MAXAG)
return -EIO;

if (atomic_read(&JFS_SBI(pip->i_sb)->bmap->db_active[agno])) {
--