On Fri, 23 Sept 2022 at 16:51, Hawkins Jiawei <yin31149@xxxxxxxxx> wrote: > > Syzkaller reports slab-out-of-bounds bug as follows: > ================================================================== > BUG: KASAN: slab-out-of-bounds in run_unpack+0x8b7/0x970 fs/ntfs3/run.c:944 > Read of size 1 at addr ffff88801bbdff02 by task syz-executor131/3611 > > [...] > Call Trace: > <TASK> > __dump_stack lib/dump_stack.c:88 [inline] > dump_stack_lvl+0xcd/0x134 lib/dump_stack.c:106 > print_address_description mm/kasan/report.c:317 [inline] > print_report.cold+0x2ba/0x719 mm/kasan/report.c:433 > kasan_report+0xb1/0x1e0 mm/kasan/report.c:495 > run_unpack+0x8b7/0x970 fs/ntfs3/run.c:944 > run_unpack_ex+0xb0/0x7c0 fs/ntfs3/run.c:1057 > ntfs_read_mft fs/ntfs3/inode.c:368 [inline] > ntfs_iget5+0xc20/0x3280 fs/ntfs3/inode.c:501 > ntfs_loadlog_and_replay+0x124/0x5d0 fs/ntfs3/fsntfs.c:272 > ntfs_fill_super+0x1eff/0x37f0 fs/ntfs3/super.c:1018 > get_tree_bdev+0x440/0x760 fs/super.c:1323 > vfs_get_tree+0x89/0x2f0 fs/super.c:1530 > do_new_mount fs/namespace.c:3040 [inline] > path_mount+0x1326/0x1e20 fs/namespace.c:3370 > do_mount fs/namespace.c:3383 [inline] > __do_sys_mount fs/namespace.c:3591 [inline] > __se_sys_mount fs/namespace.c:3568 [inline] > __x64_sys_mount+0x27f/0x300 fs/namespace.c:3568 > do_syscall_x64 arch/x86/entry/common.c:50 [inline] > do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80 > entry_SYSCALL_64_after_hwframe+0x63/0xcd > [...] > </TASK> > > The buggy address belongs to the physical page: > page:ffffea00006ef600 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x1bbd8 > head:ffffea00006ef600 order:3 compound_mapcount:0 compound_pincount:0 > flags: 0xfff00000010200(slab|head|node=0|zone=1|lastcpupid=0x7ff) > page dumped because: kasan: bad access detected > > Memory state around the buggy address: > ffff88801bbdfe00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc > ffff88801bbdfe80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc > >ffff88801bbdff00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc > ^ > ffff88801bbdff80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc > ffff88801bbe0000: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb > ================================================================== > > Kernel will tries to read record and parse MFT from disk in > ntfs_read_mft(). > > Yet the problem is that during enumerating attributes in record, > kernel doesn't check whether run_off field loading from the disk > is a valid value. > > To be more specific, if attr->nres.run_off is larger than attr->size, > kernel will passes an invalid argument run_buf_size in > run_unpack_ex(), which having an integer overflow. Then this invalid > argument will triggers the slab-out-of-bounds Read bug as above. > > This patch solves it by adding the sanity check between > the offset to packed runs and attribute size. > > Signed-off-by: Hawkins Jiawei <yin31149@xxxxxxxxx> > --- > fs/ntfs3/inode.c | 5 +++++ > 1 file changed, 5 insertions(+) > > diff --git a/fs/ntfs3/inode.c b/fs/ntfs3/inode.c > index 51363d4e8636..443a32f789ff 100644 > --- a/fs/ntfs3/inode.c > +++ b/fs/ntfs3/inode.c > @@ -365,6 +365,11 @@ static struct inode *ntfs_read_mft(struct inode *inode, > roff = le16_to_cpu(attr->nres.run_off); > > t64 = le64_to_cpu(attr->nres.svcn); > + > + /* offset to packed runs is out-of-bounds */ > + if (roff > asize) > + goto out; > + > err = run_unpack_ex(run, sbi, ino, t64, le64_to_cpu(attr->nres.evcn), > t64, Add2Ptr(attr, roff), asize - roff); > if (err < 0) > -- > 2.25.1 > return -EINVAL when roff is out-of-bounds #syz test https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master diff --git a/fs/ntfs3/inode.c b/fs/ntfs3/inode.c index 51363d4e8636..10723231e482 100644 --- a/fs/ntfs3/inode.c +++ b/fs/ntfs3/inode.c @@ -365,6 +365,13 @@ static struct inode *ntfs_read_mft(struct inode *inode, roff = le16_to_cpu(attr->nres.run_off); t64 = le64_to_cpu(attr->nres.svcn); + + /* offset to packed runs is out-of-bounds */ + if (roff > asize) { + err = -EINVAL; + goto out; + } + err = run_unpack_ex(run, sbi, ino, t64, le64_to_cpu(attr->nres.evcn), t64, Add2Ptr(attr, roff), asize - roff); if (err < 0)
