From: ChenXiaoSong chenxiaosong2@huawei.com
commit 38c9c22a85aeed28d0831f230136e9cf6fa2ed44 upstream.
Syzkaller reported use-after-free bug as follows:
================================================================== BUG: KASAN: use-after-free in ntfs_ucsncmp+0x123/0x130 Read of size 2 at addr ffff8880751acee8 by task a.out/879
CPU: 7 PID: 879 Comm: a.out Not tainted 5.19.0-rc4-next-20220630-00001-gcc5218c8bd2c-dirty #7 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.16.0-0-gd239552ce722-prebuilt.qemu.org 04/01/2014 Call Trace: <TASK> dump_stack_lvl+0x1c0/0x2b0 print_address_description.constprop.0.cold+0xd4/0x484 print_report.cold+0x55/0x232 kasan_report+0xbf/0xf0 ntfs_ucsncmp+0x123/0x130 ntfs_are_names_equal.cold+0x2b/0x41 ntfs_attr_find+0x43b/0xb90 ntfs_attr_lookup+0x16d/0x1e0 ntfs_read_locked_attr_inode+0x4aa/0x2360 ntfs_attr_iget+0x1af/0x220 ntfs_read_locked_inode+0x246c/0x5120 ntfs_iget+0x132/0x180 load_system_files+0x1cc6/0x3480 ntfs_fill_super+0xa66/0x1cf0 mount_bdev+0x38d/0x460 legacy_get_tree+0x10d/0x220 vfs_get_tree+0x93/0x300 do_new_mount+0x2da/0x6d0 path_mount+0x496/0x19d0 __x64_sys_mount+0x284/0x300 do_syscall_64+0x3b/0xc0 entry_SYSCALL_64_after_hwframe+0x46/0xb0 RIP: 0033:0x7f3f2118d9ea Code: 48 8b 0d a9 f4 0b 00 f7 d8 64 89 01 48 83 c8 ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 49 89 ca b8 a5 00 00 00 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 8b 0d 76 f4 0b 00 f7 d8 64 89 01 48 RSP: 002b:00007ffc269deac8 EFLAGS: 00000202 ORIG_RAX: 00000000000000a5 RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007f3f2118d9ea RDX: 0000000020000000 RSI: 0000000020000100 RDI: 00007ffc269dec00 RBP: 00007ffc269dec80 R08: 00007ffc269deb00 R09: 00007ffc269dec44 R10: 0000000000000000 R11: 0000000000000202 R12: 000055f81ab1d220 R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000 </TASK>
The buggy address belongs to the physical page: page:0000000085430378 refcount:1 mapcount:1 mapping:0000000000000000 index:0x555c6a81d pfn:0x751ac memcg:ffff888101f7e180 anon flags: 0xfffffc00a0014(uptodate|lru|mappedtodisk|swapbacked|node=0|zone=1|lastcpupid=0x1fffff) raw: 000fffffc00a0014 ffffea0001bf2988 ffffea0001de2448 ffff88801712e201 raw: 0000000555c6a81d 0000000000000000 0000000100000000 ffff888101f7e180 page dumped because: kasan: bad access detected
Memory state around the buggy address: ffff8880751acd80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ffff8880751ace00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
ffff8880751ace80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
^ ffff8880751acf00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ffff8880751acf80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ==================================================================
The reason is that struct ATTR_RECORD->name_offset is 6485, end address of name string is out of bounds.
Fix this by adding sanity check on end address of attribute name string.
[akpm@linux-foundation.org: coding-style cleanups] [chenxiaosong2@huawei.com: cleanup suggested by Hawkins Jiawei] Link: https://lkml.kernel.org/r/20220709064511.3304299-1-chenxiaosong2@huawei.com Link: https://lkml.kernel.org/r/20220707105329.4020708-1-chenxiaosong2@huawei.com Signed-off-by: ChenXiaoSong chenxiaosong2@huawei.com Signed-off-by: Hawkins Jiawei yin31149@gmail.com Cc: Anton Altaparmakov anton@tuxera.com Cc: ChenXiaoSong chenxiaosong2@huawei.com Cc: Yongqiang Liu liuyongqiang13@huawei.com Cc: Zhang Yi yi.zhang@huawei.com Cc: Zhang Xiaoxu zhangxiaoxu5@huawei.com Signed-off-by: Andrew Morton akpm@linux-foundation.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- fs/ntfs/attrib.c | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-)
--- a/fs/ntfs/attrib.c +++ b/fs/ntfs/attrib.c @@ -592,8 +592,12 @@ static int ntfs_attr_find(const ATTR_TYP a = (ATTR_RECORD*)((u8*)ctx->attr + le32_to_cpu(ctx->attr->length)); for (;; a = (ATTR_RECORD*)((u8*)a + le32_to_cpu(a->length))) { - if ((u8*)a < (u8*)ctx->mrec || (u8*)a > (u8*)ctx->mrec + - le32_to_cpu(ctx->mrec->bytes_allocated)) + u8 *mrec_end = (u8 *)ctx->mrec + + le32_to_cpu(ctx->mrec->bytes_allocated); + u8 *name_end = (u8 *)a + le16_to_cpu(a->name_offset) + + a->name_length * sizeof(ntfschar); + if ((u8*)a < (u8*)ctx->mrec || (u8*)a > mrec_end || + name_end > mrec_end) break; ctx->attr = a; if (unlikely(le32_to_cpu(a->type) > le32_to_cpu(type) ||