From: Baokun Li <libaokun1@xxxxxxxxxx> commit fa83c34e3e56b3c672af38059e066242655271b1 upstream. When ext4_iomap_overwrite_begin() calls ext4_iomap_begin() map blocks may fail for some reason (e.g. memory allocation failure, bare disk write), and later because "iomap->type ! = IOMAP_MAPPED" triggers WARN_ON(). When ext4 iomap_begin() returns an error, it is normal that the type of iomap->type may not match the expectation. Therefore, we only determine if iomap->type is as expected when ext4_iomap_begin() is executed successfully. Cc: stable@xxxxxxxxxx Reported-by: syzbot+08106c4b7d60702dbc14@xxxxxxxxxxxxxxxxxxxxxxxxx Link: https://lore.kernel.org/all/00000000000015760b05f9b4eee9@xxxxxxxxxx Signed-off-by: Baokun Li <libaokun1@xxxxxxxxxx> Reviewed-by: Jan Kara <jack@xxxxxxx> Link: https://lore.kernel.org/r/20230505132429.714648-1-libaokun1@xxxxxxxxxx Signed-off-by: Theodore Ts'o <tytso@xxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- fs/ext4/inode.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) --- a/fs/ext4/inode.c +++ b/fs/ext4/inode.c @@ -3478,7 +3478,7 @@ static int ext4_iomap_overwrite_begin(st */ flags &= ~IOMAP_WRITE; ret = ext4_iomap_begin(inode, offset, length, flags, iomap, srcmap); - WARN_ON_ONCE(iomap->type != IOMAP_MAPPED); + WARN_ON_ONCE(!ret && iomap->type != IOMAP_MAPPED); return ret; }
