jfs: add check read-only before txBeginAnon() call
In the Linux kernel, the following vulnerability has been resolved:
jfs: add check read-only before txBeginAnon() call
Added a read-only check before calling txBeginAnon in extAlloc
and extRecord. This prevents modification attempts on a read-only
mounted filesystem, avoiding potential errors or crashes.
Call trace: txBeginAnon+0xac/0x154 extAlloc+0xe8/0xdec fs/jfs/jfs_extent.c:78 jfs_get_block+0x340/0xb98 fs/jfs/inode.c:248 __block_write_begin_int+0x580/0x166c fs/buffer.c:2128 __block_write_begin fs/buffer.c:2177 [inline] block_write_begin+0x98/0x11c fs/buffer.c:2236 jfs_write_begin+0x44/0x88 fs/jfs/inode.c:299