From: Deepanshu Kartikey Date: Thu, 19 Mar 2026 07:45:46 +0000 (+0530) Subject: fs/ntfs3: fix missing run load for vcn0 in attr_data_get_block_locked() X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=d7ea8495fd307b58f8867acd81a1b40075b1d3ba;p=thirdparty%2Flinux.git fs/ntfs3: fix missing run load for vcn0 in attr_data_get_block_locked() When a compressed or sparse attribute has its clusters frame-aligned, vcn is rounded down to the frame start using cmask, which can result in vcn != vcn0. In this case, vcn and vcn0 may reside in different attribute segments. The code already handles the case where vcn is in a different segment by loading its runs before allocation. However, it fails to load runs for vcn0 when vcn0 resides in a different segment than vcn. This causes run_lookup_entry() to return SPARSE_LCN for vcn0 since its segment was never loaded into the in-memory run list, triggering the WARN_ON(1). Fix this by adding a missing check for vcn0 after the existing vcn segment check. If vcn0 falls outside the current segment range [svcn, evcn1), find and load the attribute segment containing vcn0 before performing the run lookup. The following scenario triggers the bug: attr_data_get_block_locked() vcn = vcn0 & cmask <- vcn != vcn0 after frame alignment load runs for vcn segment <- vcn0 segment not loaded! attr_allocate_clusters() <- allocation succeeds run_lookup_entry(vcn0) <- vcn0 not in run -> SPARSE_LCN WARN_ON(1) <- bug fires here! Reported-by: syzbot+c1e9aedbd913fadad617@syzkaller.appspotmail.com Closes: https://syzkaller.appspot.com/bug?extid=c1e9aedbd913fadad617 Fixes: c380b52f6c57 ("fs/ntfs3: Change new sparse cluster processing") Signed-off-by: Deepanshu Kartikey Signed-off-by: Konstantin Komarov --- diff --git a/fs/ntfs3/attrib.c b/fs/ntfs3/attrib.c index 6cb9bc5d605c..76e581d3961d 100644 --- a/fs/ntfs3/attrib.c +++ b/fs/ntfs3/attrib.c @@ -1152,6 +1152,21 @@ again: if (err) goto out; } + + if (vcn0 < svcn || evcn1 <= vcn0) { + struct ATTRIB *attr2; + + attr2 = ni_find_attr(ni, attr_b, &le_b, ATTR_DATA, NULL, + 0, &vcn0, &mi); + if (!attr2) { + err = -EINVAL; + goto out; + } + err = attr_load_runs(attr2, ni, run, NULL); + if (err) + goto out; + } + da = false; /* no delalloc for compressed file. */ }