github-mirror/linux
1
0
Fork 0
mirror of https://github.com/torvalds/linux.git synced 2026-05-24 23:22:31 +02:00
Code Issues Actions Packages Projects Releases Wiki Activity Graph

fs/ntfs3: prevent uninitialized lcn caused by zero len

Browse Source 
syzbot reported a uninit-value in ntfs_iomap_begin [1].

Since runs was not touched yet, run_lookup_entry() immediately fails
and returns false, which makes the value of "*len" 0.
Simultaneously, the new value and err value are also 0, causing the
logic in attr_data_get_block_locked() to jump directly to ok, ultimately
resulting in *lcn being triggered before it is set [1].

In ntfs_iomap_begin(), the check for a 0 value in clen is moved forward
to before updating lcn to avoid this [1].

[1]
BUG: KMSAN: uninit-value in ntfs_iomap_begin+0x8c0/0x1460 fs/ntfs3/inode.c:825
 ntfs_iomap_begin+0x8c0/0x1460 fs/ntfs3/inode.c:825
 iomap_iter+0x9b7/0x1540 fs/iomap/iter.c:110

Local variable lcn created at:
 ntfs_iomap_begin+0x15d/0x1460 fs/ntfs3/inode.c:786

Fixes: 10d7c95af0 ("fs/ntfs3: add delayed-allocation (delalloc) support")
Reported-by: syzbot+7be88937363ac7ab7bb0@syzkaller.appspotmail.com
Closes: https://syzkaller.appspot.com/bug?extid=7be88937363ac7ab7bb0
Tested-by: syzbot+7be88937363ac7ab7bb0@syzkaller.appspotmail.com
Signed-off-by: Edward Adam Davis <eadavis@qq.com>
Signed-off-by: Konstantin Komarov <almaz.alexandrovich@paragon-software.com>
This commit is contained in:
Edward Adam Davis 2026-02-23 16:01:13 +08:00 committed by Konstantin Komarov
parent 48d9b57b16
commit e98266e823
No known key found for this signature in database
GPG Key ID: A9B0331F832407B6
1 changed files with 5 additions and 5 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

10
fs/ntfs3/inode.c
View File

@ -827,6 +827,11 @@ static int ntfs_iomap_begin(struct inode *inode, loff_t offset, loff_t length,
return err;
}
if (!clen) {
/* broken file? */
return -EINVAL;
}
if (lcn == EOF_LCN) {
/* request out of file. */
if (flags & IOMAP_REPORT) {
@ -860,11 +865,6 @@ static int ntfs_iomap_begin(struct inode *inode, loff_t offset, loff_t length,
return 0;
}
if (!clen) {
/* broken file? */
return -EINVAL;
}
iomap->bdev = inode->i_sb->s_bdev;
iomap->offset = offset;
iomap->length = ((loff_t)clen << cluster_bits) - off;