[PATCH 5.15 37/78] [PATCH AUTOSEL 4.14 9/9] FS: JFS: Check for read-only mounted filesystem in txBegin

[ 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@gmail.com Signed-off-by: Dave Kleikamp dave.kleikamp@oracle.com Signed-off-by: Sasha Levin sashal@kernel.org --- fs/jfs/jfs_txnmgr.c | 5 +++++ 1 file changed, 5 insertions(+)

--- a/fs/jfs/jfs_txnmgr.c +++ b/fs/jfs/jfs_txnmgr.c @@ -354,6 +354,11 @@ tid_t txBegin(struct super_block *sb, in 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);