KASAN: slab-use-after-free Read in iopt_unmap_iova_range

[Xingyuan Mo]

Hello,

Recently, when using our tool to fuzz kernel, the following bug was
triggered.

HEAD commit: 09a9639e56c0 ("Linux 6.3-rc6")
git tree: mainline
compiler: gcc (Ubuntu 10.3.0-1ubuntu1~20.04) 10.3.0
kernel config: https://drive.google.com/file/d/1FoYieVV2RhjXXwTcmsUzz8dT6_DN61w8/view?usp=share_link
C reproducer: https://drive.google.com/file/d/1OGmuq_C9DsG78CTMex3Wiq7sPBB6fKkX/view?usp=share_link

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: Xingyuan Mo <hdt...@gmail.com>

Kernel log:

BUG: KASAN: slab-use-after-free in iopt_unmap_iova_range+0x5ba/0x5f0 drivers/iommu/iommufd/io_pagetable.c:499
Read of size 4 at addr ffff88814fb28984 by task syz-executor410/8190

CPU: 0 PID: 8190 Comm: syz-executor410 Not tainted 6.3.0-rc6 #3
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.13.0-1ubuntu1.1 04/01/2014
Call Trace:
<TASK>
__dump_stack lib/dump_stack.c:88 [inline]
dump_stack_lvl+0xd9/0x150 lib/dump_stack.c:106
print_address_description.constprop.0+0x2c/0x3c0 mm/kasan/report.c:319
print_report mm/kasan/report.c:430 [inline]
kasan_report+0x11c/0x130 mm/kasan/report.c:536
iopt_unmap_iova_range+0x5ba/0x5f0 drivers/iommu/iommufd/io_pagetable.c:499
iopt_unmap_all+0x27/0x50 drivers/iommu/iommufd/io_pagetable.c:555
iommufd_ioas_unmap+0x3d1/0x480 drivers/iommu/iommufd/ioas.c:300
iommufd_fops_ioctl+0x317/0x4b0 drivers/iommu/iommufd/main.c:337
vfs_ioctl fs/ioctl.c:51 [inline]
__do_sys_ioctl fs/ioctl.c:870 [inline]
__se_sys_ioctl fs/ioctl.c:856 [inline]
__x64_sys_ioctl+0x197/0x210 fs/ioctl.c:856
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x39/0xb0 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x63/0xcd
RIP: 0033:0x7f5bc153dbdd
Code: c3 e8 97 2a 00 00 0f 1f 80 00 00 00 00 f3 0f 1e fa 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 b8 ff ff ff f7 d8 64
89 01 48
RSP: 002b:00007f5bc14c2d88 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007f5bc15d12f8 RCX: 00007f5bc153dbdd
RDX: 0000000020000000 RSI: 0000000000003b86 RDI: 0000000000000000
RBP: 00007f5bc15d12f0 R08: 00007f5bc14c3700 R09: 0000000000000000
R10: 00007f5bc14c3700 R11: 0000000000000246 R12: 00007f5bc15d12fc
R13: 00007f5bc159e074 R14: 6d6f692f7665642f R15: 00007f5bc14c2e80
</TASK>

Allocated by task 8189:
kasan_save_stack+0x22/0x40 mm/kasan/common.c:45
kasan_set_track+0x25/0x30 mm/kasan/common.c:52
____kasan_kmalloc mm/kasan/common.c:374 [inline]
____kasan_kmalloc mm/kasan/common.c:333 [inline]
__kasan_kmalloc+0xa2/0xb0 mm/kasan/common.c:383
kmalloc include/linux/slab.h:580 [inline]
kzalloc include/linux/slab.h:720 [inline]
iopt_alloc_area_pages+0x94/0x560 drivers/iommu/iommufd/io_pagetable.c:234
iopt_map_pages drivers/iommu/iommufd/io_pagetable.c:339 [inline]
iopt_map_user_pages+0x205/0x4e0 drivers/iommu/iommufd/io_pagetable.c:404
iommufd_ioas_map+0x329/0x5f0 drivers/iommu/iommufd/ioas.c:222
iommufd_fops_ioctl+0x317/0x4b0 drivers/iommu/iommufd/main.c:337
vfs_ioctl fs/ioctl.c:51 [inline]
__do_sys_ioctl fs/ioctl.c:870 [inline]
__se_sys_ioctl fs/ioctl.c:856 [inline]
__x64_sys_ioctl+0x197/0x210 fs/ioctl.c:856
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x39/0xb0 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x63/0xcd

Freed by task 8189:
kasan_save_stack+0x22/0x40 mm/kasan/common.c:45
kasan_set_track+0x25/0x30 mm/kasan/common.c:52
kasan_save_free_info+0x2e/0x40 mm/kasan/generic.c:521
____kasan_slab_free mm/kasan/common.c:236 [inline]
____kasan_slab_free+0x160/0x1c0 mm/kasan/common.c:200
kasan_slab_free include/linux/kasan.h:162 [inline]
slab_free_hook mm/slub.c:1781 [inline]
slab_free_freelist_hook+0x8b/0x1c0 mm/slub.c:1807
slab_free mm/slub.c:3787 [inline]
__kmem_cache_free+0xaf/0x2d0 mm/slub.c:3800
iopt_abort_area drivers/iommu/iommufd/io_pagetable.c:292 [inline]
iopt_unmap_iova_range+0x288/0x5f0 drivers/iommu/iommufd/io_pagetable.c:509
iopt_unmap_all+0x27/0x50 drivers/iommu/iommufd/io_pagetable.c:555
iommufd_ioas_unmap+0x3d1/0x480 drivers/iommu/iommufd/ioas.c:300
iommufd_fops_ioctl+0x317/0x4b0 drivers/iommu/iommufd/main.c:337
vfs_ioctl fs/ioctl.c:51 [inline]
__do_sys_ioctl fs/ioctl.c:870 [inline]
__se_sys_ioctl fs/ioctl.c:856 [inline]
__x64_sys_ioctl+0x197/0x210 fs/ioctl.c:856
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x39/0xb0 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x63/0xcd

The buggy address belongs to the object at ffff88814fb28900
which belongs to the cache kmalloc-cg-192 of size 192
The buggy address is located 132 bytes inside of
freed 192-byte region [ffff88814fb28900, ffff88814fb289c0)

The buggy address belongs to the physical page:
page:ffffea00053eca00 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x14fb28
memcg:ffff888150318b01
flags: 0x57ff00000000200(slab|node=1|zone=2|lastcpupid=0x7ff)
raw: 057ff00000000200 ffff88801244ddc0 dead000000000122 0000000000000000
raw: 0000000000000000 0000000080100010 00000001ffffffff ffff888150318b01
page dumped because: kasan: bad access detected
page_owner tracks the page as allocated
page last allocated via order 0, migratetype Unmovable, gfp_mask 0x12cc0(GFP_KERNEL|__GFP_NOWARN|__GFP_NORETRY), pid 8173, tgid 8172 (syz-executor410), ts 70683710169, free_ts 67978925587
prep_new_page mm/page_alloc.c:2553 [inline]
get_page_from_freelist+0x1190/0x2e20 mm/page_alloc.c:4326
__alloc_pages+0x1cb/0x4a0 mm/page_alloc.c:5592
alloc_pages+0x1aa/0x270 mm/mempolicy.c:2283
alloc_slab_page mm/slub.c:1851 [inline]
allocate_slab+0x25f/0x390 mm/slub.c:1998
new_slab mm/slub.c:2051 [inline]
___slab_alloc+0xa9b/0x13e0 mm/slub.c:3193
__slab_alloc.constprop.0+0x56/0xa0 mm/slub.c:3292
__slab_alloc_node mm/slub.c:3345 [inline]
slab_alloc_node mm/slub.c:3442 [inline]
__kmem_cache_alloc_node+0x136/0x320 mm/slub.c:3491
kmalloc_trace+0x26/0xe0 mm/slab_common.c:1061
kmalloc include/linux/slab.h:580 [inline]
kzalloc include/linux/slab.h:720 [inline]
iommufd_test_alloc_access drivers/iommu/iommufd/selftest.c:534 [inline]
iommufd_test_create_access drivers/iommu/iommufd/selftest.c:563 [inline]
iommufd_test+0x124a/0x2720 drivers/iommu/iommufd/selftest.c:810
iommufd_fops_ioctl+0x317/0x4b0 drivers/iommu/iommufd/main.c:337
vfs_ioctl fs/ioctl.c:51 [inline]
__do_sys_ioctl fs/ioctl.c:870 [inline]
__se_sys_ioctl fs/ioctl.c:856 [inline]
__x64_sys_ioctl+0x197/0x210 fs/ioctl.c:856
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x39/0xb0 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x63/0xcd
page last free stack trace:
reset_page_owner include/linux/page_owner.h:24 [inline]
free_pages_prepare mm/page_alloc.c:1454 [inline]
free_pcp_prepare+0x5d5/0xa50 mm/page_alloc.c:1504
free_unref_page_prepare mm/page_alloc.c:3388 [inline]
free_unref_page+0x1d/0x490 mm/page_alloc.c:3483
__folio_put_small mm/swap.c:106 [inline]
__folio_put+0xc5/0x140 mm/swap.c:129
folio_put include/linux/mm.h:1309 [inline]
put_page include/linux/mm.h:1378 [inline]
anon_pipe_buf_release+0x3fb/0x4c0 fs/pipe.c:138
pipe_buf_release include/linux/pipe_fs_i.h:203 [inline]
pipe_read+0x614/0x1110 fs/pipe.c:324
call_read_iter include/linux/fs.h:1845 [inline]
new_sync_read fs/read_write.c:389 [inline]
vfs_read+0x7fa/0x930 fs/read_write.c:470
ksys_read+0x1ec/0x250 fs/read_write.c:613
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x39/0xb0 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x63/0xcd

Memory state around the buggy address:
ffff88814fb28880: fb fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc
ffff88814fb28900: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>ffff88814fb28980: fb fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc
^
ffff88814fb28a00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
ffff88814fb28a80: 00 00 00 00 00 00 00 fc fc fc fc fc fc fc fc fc