hfs: fix OOB Read in __hfs_brec_find

ZhangPeng · akpm00 · commit 8d824e69d9f3 · 2022-12-11T19:30:19.000-08:00
Syzbot reported a OOB read bug: ================================================================== BUG: KASAN: slab-out-of-bounds in hfs_strcmp+0x117/0x190 fs/hfs/string.c:84 Read of size 1 at addr ffff88807eb62c4e by task kworker/u4:1/11 CPU: 1 PID: 11 Comm: kworker/u4:1 Not tainted 6.1.0-rc6-syzkaller-00308-g644e9524388a #0 Workqueue: writeback wb_workfn (flush-7:0) Call Trace: <TASK> __dump_stack lib/dump_stack.c:88 [inline] dump_stack_lvl+0x1b1/0x28e lib/dump_stack.c:106 print_address_description+0x74/0x340 mm/kasan/report.c:284 print_report+0x107/0x1f0 mm/kasan/report.c:395 kasan_report+0xcd/0x100 mm/kasan/report.c:495 hfs_strcmp+0x117/0x190 fs/hfs/string.c:84 __hfs_brec_find+0x213/0x5c0 fs/hfs/bfind.c:75 hfs_brec_find+0x276/0x520 fs/hfs/bfind.c:138 hfs_write_inode+0x34c/0xb40 fs/hfs/inode.c:462 write_inode fs/fs-writeback.c:1440 [inline] If the input inode of hfs_write_inode() is incorrect: struct inode struct hfs_inode_info struct hfs_cat_key struct hfs_name u8 len # len is greater than HFS_NAMELEN(31) which is the maximum length of an HFS filename OOB read occurred: hfs_write_inode() hfs_brec_find() __hfs_brec_find() hfs_cat_keycmp() hfs_strcmp() # OOB read occurred due to len is too large Fix this by adding a Check on len in hfs_write_inode() before calling hfs_brec_find(). Link: https://lkml.kernel.org/r/20221130065959.2168236-1-zhangpeng362@huawei.com Signed-off-by: ZhangPeng <zhangpeng362@huawei.com> Reported-by: <syzbot+e836ff7133ac02be825f@syzkaller.appspotmail.com> Cc: Damien Le Moal <damien.lemoal@opensource.wdc.com> Cc: Ira Weiny <ira.weiny@intel.com> Cc: Jeff Layton <jlayton@kernel.org> Cc: Kefeng Wang <wangkefeng.wang@huawei.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: Nanyong Sun <sunnanyong@huawei.com> Cc: Viacheslav Dubeyko <slava@dubeyko.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
diff --git a/fs/hfs/inode.c b/fs/hfs/inode.c
@@ -458,6 +458,8 @@ int hfs_write_inode(struct inode *inode, struct writeback_control *wbc)
 		/* panic? */
 		return -EIO;
 
+	if (HFS_I(main_inode)->cat_key.CName.len > HFS_NAMELEN)
+		return -EIO;
 	fd.search_key->cat = HFS_I(main_inode)->cat_key;
 	if (hfs_brec_find(&fd))
 		/* panic? */
