Re: [syzbot] [iommu?] KASAN: slab-use-after-free Read in iopt_unmap_iova_range

From: syzbot
Date: Sun Jun 25 2023 - 10:03:49 EST

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syzbot has found a reproducer for the following issue on:

HEAD commit: a92b7d26c743 Merge tag 'drm-fixes-2023-06-23' of git://ano..
git tree: upstream
console+strace: https://syzkaller.appspot.com/x/log.txt?x=1642c4c7280000
kernel config: https://syzkaller.appspot.com/x/.config?x=2cbd298d0aff1140
dashboard link: https://syzkaller.appspot.com/bug?extid=1ad12d16afca0e7d2dde
compiler: gcc (Debian 10.2.1-6) 10.2.1 20210110, GNU ld (GNU Binutils for Debian) 2.35.2
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=16d77fb0a80000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=11cb8093280000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/732ee8ad13ec/disk-a92b7d26.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/26b49ff43e67/vmlinux-a92b7d26.xz
kernel image: https://storage.googleapis.com/syzbot-assets/2749c666f682/bzImage-a92b7d26.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+1ad12d16afca0e7d2dde@xxxxxxxxxxxxxxxxxxxxxxxxx

==================================================================
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 ffff88807683c184 by task syz-executor144/5064

CPU: 0 PID: 5064 Comm: syz-executor144 Not tainted 6.4.0-rc7-syzkaller-00226-ga92b7d26c743 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/27/2023
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:351
print_report mm/kasan/report.c:462 [inline]
kasan_report+0x11c/0x130 mm/kasan/report.c:572
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+0x3d0/0x490 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: 0033:0x7f5a36a77bc9
Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 11 15 00 00 90 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:00007f5a36a29308 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007f5a36aff428 RCX: 00007f5a36a77bc9
RDX: 00000000200001c0 RSI: 0000000000003b86 RDI: 0000000000000003
RBP: 00007f5a36aff420 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00007f5a36aff42c
R13: 00007f5a36acd064 R14: 6d6f692f7665642f R15: 0000000000022000
</TASK>

Allocated by task 5064:
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:559 [inline]
kzalloc include/linux/slab.h:680 [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 5065:
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:3786 [inline]
__kmem_cache_free+0xaf/0x2d0 mm/slub.c:3799
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+0x3d0/0x490 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 ffff88807683c100
which belongs to the cache kmalloc-cg-192 of size 192
The buggy address is located 132 bytes inside of
freed 192-byte region [ffff88807683c100, ffff88807683c1c0)

The buggy address belongs to the physical page:
page:ffffea0001da0f00 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x7683c
flags: 0xfff00000000200(slab|node=0|zone=1|lastcpupid=0x7ff)
page_type: 0xffffffff()
raw: 00fff00000000200 ffff88801244ddc0 dead000000000122 0000000000000000
raw: 0000000000000000 0000000080100010 00000001ffffffff 0000000000000000
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 5064, tgid 5063 (syz-executor144), ts 60389083823, free_ts 60371796624
set_page_owner include/linux/page_owner.h:31 [inline]
post_alloc_hook+0x2db/0x350 mm/page_alloc.c:1731
prep_new_page mm/page_alloc.c:1738 [inline]
get_page_from_freelist+0xf41/0x2c00 mm/page_alloc.c:3502
__alloc_pages+0x1cb/0x4a0 mm/page_alloc.c:4768
alloc_pages+0x1aa/0x270 mm/mempolicy.c:2279
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+0xa91/0x1400 mm/slub.c:3192
__slab_alloc.constprop.0+0x56/0xa0 mm/slub.c:3291
__slab_alloc_node mm/slub.c:3344 [inline]
slab_alloc_node mm/slub.c:3441 [inline]
__kmem_cache_alloc_node+0x136/0x320 mm/slub.c:3490
kmalloc_trace+0x26/0xe0 mm/slab_common.c:1057
kmalloc include/linux/slab.h:559 [inline]
kzalloc include/linux/slab.h:680 [inline]
iommufd_test_alloc_access drivers/iommu/iommufd/selftest.c:680 [inline]
iommufd_test_create_access drivers/iommu/iommufd/selftest.c:710 [inline]
iommufd_test+0x1328/0x2c20 drivers/iommu/iommufd/selftest.c:961
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:1302 [inline]
free_unref_page_prepare+0x62e/0xcb0 mm/page_alloc.c:2564
free_unref_page_list+0xe3/0xa70 mm/page_alloc.c:2705
release_pages+0xcd8/0x1380 mm/swap.c:1042
tlb_batch_pages_flush+0xa8/0x1a0 mm/mmu_gather.c:97
tlb_flush_mmu_free mm/mmu_gather.c:292 [inline]
tlb_flush_mmu mm/mmu_gather.c:299 [inline]
tlb_finish_mmu+0x14b/0x7e0 mm/mmu_gather.c:391
exit_mmap+0x2b2/0x930 mm/mmap.c:3120
__mmput+0x128/0x4c0 kernel/fork.c:1351
mmput+0x60/0x70 kernel/fork.c:1373
exit_mm kernel/exit.c:567 [inline]
do_exit+0x9b0/0x29b0 kernel/exit.c:861
do_group_exit+0xd4/0x2a0 kernel/exit.c:1024
get_signal+0x2318/0x25b0 kernel/signal.c:2876
arch_do_signal_or_restart+0x79/0x5c0 arch/x86/kernel/signal.c:306
exit_to_user_mode_loop kernel/entry/common.c:168 [inline]
exit_to_user_mode_prepare+0x11f/0x240 kernel/entry/common.c:204
__syscall_exit_to_user_mode_work kernel/entry/common.c:286 [inline]
syscall_exit_to_user_mode+0x1d/0x50 kernel/entry/common.c:297
do_syscall_64+0x46/0xb0 arch/x86/entry/common.c:86
entry_SYSCALL_64_after_hwframe+0x63/0xcd

Memory state around the buggy address:
ffff88807683c080: 00 00 00 00 00 00 00 fc fc fc fc fc fc fc fc fc
ffff88807683c100: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>ffff88807683c180: fb fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc
^
ffff88807683c200: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
ffff88807683c280: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
==================================================================

---
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#syz test: git://repo/address.git branch-or-commit-hash
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Next message: Masahiro Yamada: "[PATCH v3 1/3] kbuild: unexport abs_srctree and abs_objtree"
Previous message: Jens Axboe: "Re: [PATCH v3] blk-throttle: Fix io statistics for cgroup v1"
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