From ace149e0830c380ddfce7e466fe860ca502fe4ee Mon Sep 17 00:00:00 2001 From: Trond Myklebust Date: Fri, 13 Sep 2024 13:57:04 -0400 Subject: [PATCH] filemap: Fix bounds checking in filemap_read() If the caller supplies an iocb->ki_pos value that is close to the filesystem upper limit, and an iterator with a count that causes us to overflow that limit, then filemap_read() enters an infinite loop. This behaviour was discovered when testing xfstests generic/525 with the "localio" optimisation for loopback NFS mounts. Reported-by: Mike Snitzer Fixes: c2a9737f45e2 ("vfs,mm: fix a dead loop in truncate_inode_pages_range()") Tested-by: Mike Snitzer Signed-off-by: Trond Myklebust Signed-off-by: Linus Torvalds --- mm/filemap.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/mm/filemap.c b/mm/filemap.c index 36d22968be9a..56fa431c52af 100644 --- a/mm/filemap.c +++ b/mm/filemap.c @@ -2625,7 +2625,7 @@ ssize_t filemap_read(struct kiocb *iocb, struct iov_iter *iter, if (unlikely(!iov_iter_count(iter))) return 0; - iov_iter_truncate(iter, inode->i_sb->s_maxbytes); + iov_iter_truncate(iter, inode->i_sb->s_maxbytes - iocb->ki_pos); folio_batch_init(&fbatch); do {