4.19-stable review patch. If anyone has any objections, please let me know.
------------------
From: Immad Mir <mirimmad17@xxxxxxxxx>
[ Upstream commit 95e2b352c03b0a86c5717ba1d24ea20969abcacc ]
This patch adds a check for read-only mounted filesystem
in txBegin before starting a transaction potentially saving
from NULL pointer deref.
Signed-off-by: Immad Mir <mirimmad17@xxxxxxxxx>
Signed-off-by: Dave Kleikamp <dave.kleikamp@xxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
fs/jfs/jfs_txnmgr.c | 5 +++++
1 file changed, 5 insertions(+)
diff --git a/fs/jfs/jfs_txnmgr.c b/fs/jfs/jfs_txnmgr.c
index 78789c5ed36b0..e10db01f253b8 100644
--- a/fs/jfs/jfs_txnmgr.c
+++ b/fs/jfs/jfs_txnmgr.c
@@ -367,6 +367,11 @@ tid_t txBegin(struct super_block *sb, int flag)
jfs_info("txBegin: flag = 0x%x", flag);
log = JFS_SBI(sb)->log;
+ if (!log) {
+ jfs_error(sb, "read-only filesystem\n");
+ return 0;
+ }
+
TXN_LOCK();
INCREMENT(TxStat.txBegin);
--
2.40.1
