Add check on filler to prevent NULL pointer dereference condition in read_cache_folio[1]. [1] https://syzkaller.appspot.com/bug?extid=4089e577072948ac5531 Reported-by: syzbot+4089e577072948ac5531@xxxxxxxxxxxxxxxxxxxxxxxxx Closes: https://syzkaller.appspot.com/bug?extid=4089e577072948ac5531 Tested-by: syzbot+4089e577072948ac5531@xxxxxxxxxxxxxxxxxxxxxxxxx Signed-off-by: Gianfranco Trad <gianf.trad@xxxxxxxxx> --- mm/filemap.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) diff --git a/mm/filemap.c b/mm/filemap.c index 4f3753f0a158..960f389e2d3b 100644 --- a/mm/filemap.c +++ b/mm/filemap.c @@ -2360,7 +2360,10 @@ static int filemap_read_folio(struct file *file, filler_t filler, /* Start the actual read. The read will unlock the page. */ if (unlikely(workingset)) psi_memstall_enter(&pflags); - error = filler(file, folio); + if (filler) + error = filler(file, folio); + else + return -EIO; if (unlikely(workingset)) psi_memstall_leave(&pflags); if (error) -- 2.43.0
