From: Hawkins Jiawei yin31149@gmail.com
[ Upstream commit 887bfc546097fbe8071dac13b2fef73b77920899 ]
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.
link: https://lore.kernel.org/all/0000000000009145fc05e94bd5c3@google.com/#t Reported-and-tested-by: syzbot+8d6fbb27a6aded64b25b@syzkaller.appspotmail.com Signed-off-by: Hawkins Jiawei yin31149@gmail.com Signed-off-by: Konstantin Komarov almaz.alexandrovich@paragon-software.com Signed-off-by: Sasha Levin sashal@kernel.org --- fs/ntfs3/inode.c | 7 +++++++ 1 file changed, 7 insertions(+)
diff --git a/fs/ntfs3/inode.c b/fs/ntfs3/inode.c index 66afa3db753a..00fd368e7b4a 100644 --- a/fs/ntfs3/inode.c +++ b/fs/ntfs3/inode.c @@ -373,6 +373,13 @@ static struct inode *ntfs_read_mft(struct inode *inode, }
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)