Messages in this thread | | | Date | Tue, 7 Dec 2021 18:11:53 +0000 | Subject | Re: [PATCH 0/2] Revert "block: add single bio async direct IO helper" to avoid UAF | From | Pavel Begunkov <> |
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On 12/7/21 18:09, George Kennedy wrote: > On 12/7/2021 12:36 PM, Pavel Begunkov wrote: >> On 12/7/21 15:51, George Kennedy wrote: >>> git bisect shows that commit 54a88eb838d3 >>> ("block: add single bio async direct IO helper") >>> causes the following UAF: KASAN: use-after-free Write in io_submit_one >>> >>> Tried to root-cause the issue, but need the patch submitter's help in >>> coming up with a fix. >> >> Hey George, thanks for the report. Do you have a reproducer? > > Hi Pavel, > > Forgot to include it in the cover letter. Straight from Syzkaller:
Perfect, thanks! Confirmed what I thought about is a problem, though the diff is buggy. Will take care of it
> #ifdef REF > Syzkaller hit 'KASAN: use-after-free Write in io_submit_one' bug. > > ================================================================== > BUG: KASAN: use-after-free in instrument_atomic_read_write include/linux/instrumented.h:101 [inline] > BUG: KASAN: use-after-free in atomic_fetch_sub_release include/linux/atomic/atomic-instrumented.h:167 [inline] > BUG: KASAN: use-after-free in __refcount_sub_and_test include/linux/refcount.h:272 [inline] > BUG: KASAN: use-after-free in __refcount_dec_and_test include/linux/refcount.h:315 [inline] > BUG: KASAN: use-after-free in refcount_dec_and_test include/linux/refcount.h:333 [inline] > BUG: KASAN: use-after-free in iocb_put fs/aio.c:1161 [inline] > BUG: KASAN: use-after-free in io_submit_one+0x496/0x2fe0 fs/aio.c:1882 > Write of size 4 at addr ffff888027c338a0 by task syz-executor873/15100 > > CPU: 2 PID: 15100 Comm: syz-executor873 Not tainted 5.16.0-rc1-syzk #1 > Hardware name: Red Hat KVM, BIOS 1.13.0-2.module+el8.3.0+7860+a7792d29 04/01/2014 > Call Trace: > <TASK> > __dump_stack lib/dump_stack.c:88 [inline] > dump_stack_lvl+0x89/0xb5 lib/dump_stack.c:106 > print_address_description.constprop.9+0x28/0x160 mm/kasan/report.c:247 > __kasan_report mm/kasan/report.c:433 [inline] > kasan_report.cold.14+0x7d/0x117 mm/kasan/report.c:450 > check_region_inline mm/kasan/generic.c:183 [inline] > kasan_check_range+0x18e/0x1f0 mm/kasan/generic.c:189 > __kasan_check_write+0x14/0x20 mm/kasan/shadow.c:37 > instrument_atomic_read_write include/linux/instrumented.h:101 [inline] > atomic_fetch_sub_release include/linux/atomic/atomic-instrumented.h:167 [inline] > __refcount_sub_and_test include/linux/refcount.h:272 [inline] > __refcount_dec_and_test include/linux/refcount.h:315 [inline] > refcount_dec_and_test include/linux/refcount.h:333 [inline] > iocb_put fs/aio.c:1161 [inline] > io_submit_one+0x496/0x2fe0 fs/aio.c:1882 > __do_sys_io_submit fs/aio.c:1938 [inline] > __se_sys_io_submit fs/aio.c:1908 [inline] > __x64_sys_io_submit+0x1c7/0x4a0 fs/aio.c:1908 > do_syscall_x64 arch/x86/entry/common.c:50 [inline] > do_syscall_64+0x3a/0x80 arch/x86/entry/common.c:80 > entry_SYSCALL_64_after_hwframe+0x44/0xae > RIP: 0033:0x7f43c5504289 > Code: 01 00 48 81 c4 80 00 00 00 e9 f1 fe ff ff 0f 1f 00 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 8b 0d b7 db 2c 00 f7 d8 64 89 01 48 > RSP: 002b:00007ffda542ba68 EFLAGS: 00000246 ORIG_RAX: 00000000000000d1 > RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007f43c5504289 > RDX: 0000000020000400 RSI: 0000000000000001 RDI: 00007f43c5c14000 > RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000 > R10: 0000000000000000 R11: 0000000000000246 R12: 00000000004006f0 > R13: 00007ffda542bb50 R14: 0000000000000000 R15: 0000000000000000 > </TASK> > > Allocated by task 15100: > kasan_save_stack+0x26/0x60 mm/kasan/common.c:38 > kasan_set_track mm/kasan/common.c:46 [inline] > set_alloc_info mm/kasan/common.c:434 [inline] > __kasan_slab_alloc+0x71/0x90 mm/kasan/common.c:467 > kasan_slab_alloc include/linux/kasan.h:259 [inline] > slab_post_alloc_hook+0x55/0x230 mm/slab.h:519 > slab_alloc_node mm/slub.c:3234 [inline] > slab_alloc mm/slub.c:3242 [inline] > kmem_cache_alloc+0x15a/0x2b0 mm/slub.c:3247 > aio_get_req fs/aio.c:1028 [inline] > io_submit_one+0x122/0x2fe0 fs/aio.c:1875 > __do_sys_io_submit fs/aio.c:1938 [inline] > __se_sys_io_submit fs/aio.c:1908 [inline] > __x64_sys_io_submit+0x1c7/0x4a0 fs/aio.c:1908 > do_syscall_x64 arch/x86/entry/common.c:50 [inline] > do_syscall_64+0x3a/0x80 arch/x86/entry/common.c:80 > entry_SYSCALL_64_after_hwframe+0x44/0xae > > Freed by task 15100: > kasan_save_stack+0x26/0x60 mm/kasan/common.c:38 > kasan_set_track+0x25/0x30 mm/kasan/common.c:46 > kasan_set_free_info+0x24/0x40 mm/kasan/generic.c:370 > ____kasan_slab_free mm/kasan/common.c:366 [inline] > ____kasan_slab_free mm/kasan/common.c:328 [inline] > __kasan_slab_free+0xe8/0x120 mm/kasan/common.c:374 > kasan_slab_free include/linux/kasan.h:235 [inline] > slab_free_hook mm/slub.c:1723 [inline] > slab_free_freelist_hook mm/slub.c:1749 [inline] > slab_free mm/slub.c:3513 [inline] > kmem_cache_free+0xfe/0x310 mm/slub.c:3530 > iocb_destroy fs/aio.c:1080 [inline] > iocb_put fs/aio.c:1163 [inline] > iocb_put fs/aio.c:1159 [inline] > aio_complete_rw+0xa0f/0x1010 fs/aio.c:1440 > aio_rw_done fs/aio.c:1510 [inline] > aio_read+0x352/0x4a0 fs/aio.c:1537 > __io_submit_one fs/aio.c:1830 [inline] > io_submit_one+0x478/0x2fe0 fs/aio.c:1879 > __do_sys_io_submit fs/aio.c:1938 [inline] > __se_sys_io_submit fs/aio.c:1908 [inline] > __x64_sys_io_submit+0x1c7/0x4a0 fs/aio.c:1908 > do_syscall_x64 arch/x86/entry/common.c:50 [inline] > do_syscall_64+0x3a/0x80 arch/x86/entry/common.c:80 > entry_SYSCALL_64_after_hwframe+0x44/0xae > > The buggy address belongs to the object at ffff888027c33800 > which belongs to the cache aio_kiocb of size 176 > The buggy address is located 160 bytes inside of > 176-byte region [ffff888027c33800, ffff888027c338b0) > The buggy address belongs to the page: > page:00000000dfee8ade refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x27c33 > flags: 0xfffffc0000200(slab|node=0|zone=1|lastcpupid=0x1fffff) > raw: 000fffffc0000200 ffffea0000714400 dead000000000002 ffff88810649da40 > raw: 0000000000000000 0000000080100010 00000001ffffffff 0000000000000000 > page dumped because: kasan: bad access detected > > Memory state around the buggy address: > ffff888027c33780: fb fb fb fb fb fb fc fc fc fc fc fc fc fc fc fc > ffff888027c33800: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb > >ffff888027c33880: fb fb fb fb fb fb fc fc fc fc fc fc fc fc fc fc > ^ > ffff888027c33900: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb > ffff888027c33980: fb fb fb fb fb fb fc fc fc fc fc fc fc fc fc fc > ================================================================== > ------------[ cut here ]------------ > refcount_t: underflow; use-after-free. > WARNING: CPU: 2 PID: 15100 at lib/refcount.c:28 refcount_warn_saturate+0x111/0x200 lib/refcount.c:28 > Modules linked in: > CPU: 2 PID: 15100 Comm: syz-executor873 Tainted: G B 5.16.0-rc1-syzk #1 > Hardware name: Red Hat KVM, BIOS 1.13.0-2.module+el8.3.0+7860+a7792d29 04/01/2014 > RIP: 0010:refcount_warn_saturate+0x111/0x200 lib/refcount.c:28 > Code: 1d fe 0e 02 11 31 ff 89 de e8 db 75 04 fe 84 db 75 9b e8 02 75 04 fe 48 c7 c7 60 57 53 8f c6 05 de 0e 02 11 01 e8 a8 32 7a 0a <0f> 0b e9 7c ff ff ff e8 e3 74 04 fe 0f b6 1d c4 0e 02 11 31 ff 89 > RSP: 0018:ffff88801885fc90 EFLAGS: 00010282 > RAX: 0000000000000000 RBX: 0000000000000000 RCX: ffffffff816856a5 > RDX: 0000000000000000 RSI: ffff888026f78000 RDI: 0000000000000002 > RBP: ffff88801885fca0 R08: ffffed1020f27911 R09: ffffed1020f27911 > R10: ffff88810793c887 R11: ffffed1020f27910 R12: ffff888027c338a0 > R13: 0000000000000000 R14: ffff888027c33890 R15: 0000000000000000 > FS: 00007f43c5c0d740(0000) GS:ffff888107900000(0000) knlGS:0000000000000000 > CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 > CR2: 00007f43c5c14000 CR3: 00000000247fe000 CR4: 00000000000006e0 > Call Trace: > <TASK> > __refcount_sub_and_test include/linux/refcount.h:283 [inline] > __refcount_dec_and_test include/linux/refcount.h:315 [inline] > refcount_dec_and_test include/linux/refcount.h:333 [inline] > iocb_put fs/aio.c:1161 [inline] > io_submit_one+0xfd2/0x2fe0 fs/aio.c:1882 > __do_sys_io_submit fs/aio.c:1938 [inline] > __se_sys_io_submit fs/aio.c:1908 [inline] > __x64_sys_io_submit+0x1c7/0x4a0 fs/aio.c:1908 > do_syscall_x64 arch/x86/entry/common.c:50 [inline] > do_syscall_64+0x3a/0x80 arch/x86/entry/common.c:80 > entry_SYSCALL_64_after_hwframe+0x44/0xae > RIP: 0033:0x7f43c5504289 > Code: 01 00 48 81 c4 80 00 00 00 e9 f1 fe ff ff 0f 1f 00 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 8b 0d b7 db 2c 00 f7 d8 64 89 01 48 > RSP: 002b:00007ffda542ba68 EFLAGS: 00000246 ORIG_RAX: 00000000000000d1 > RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007f43c5504289 > RDX: 0000000020000400 RSI: 0000000000000001 RDI: 00007f43c5c14000 > RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000 > R10: 0000000000000000 R11: 0000000000000246 R12: 00000000004006f0 > R13: 00007ffda542bb50 R14: 0000000000000000 R15: 0000000000000000 > </TASK> > ---[ end trace 8c5b816eed9c8016 ]--- > > > Syzkaller reproducer: > # {Threaded:false Collide:false Repeat:false RepeatTimes:0 Procs:1 Slowdown:1 Sandbox: Fault:false FaultCall:-1 FaultNth:0 Leak:false NetInjection:false NetDevices:false NetReset:false Cgroups:false BinfmtMisc:false CloseFDs:false KCSAN:false DevlinkPCI:false USB:false VhciInjection:false Wifi:false IEEE802154:false Sysctl:false UseTmpDir:false HandleSegv:false Repro:false Trace:false} > io_setup(0x3, &(0x7f0000000040)=<r0=>0x0) > r1 = openat$nullb(0xffffffffffffff9c, &(0x7f0000000000), 0x24080, 0x0) > io_submit(r0, 0x1, &(0x7f0000000400)=[&(0x7f0000000140)={0x0, 0x0, 0x0, 0x0, 0x0, r1, 0x0, 0xfe00}]) > > > C reproducer: > #endif /* REF */ > // autogenerated by syzkaller (https://github.com/google/syzkaller) > > #define _GNU_SOURCE > > #include <endian.h> > #include <stdint.h> > #include <stdio.h> > #include <stdlib.h> > #include <string.h> > #include <sys/syscall.h> > #include <sys/types.h> > #include <unistd.h> > > uint64_t r[2] = {0x0, 0xffffffffffffffff}; > > int main(void) > { > syscall(__NR_mmap, 0x1ffff000ul, 0x1000ul, 0ul, 0x32ul, -1, 0ul); > syscall(__NR_mmap, 0x20000000ul, 0x1000000ul, 7ul, 0x32ul, -1, 0ul); > syscall(__NR_mmap, 0x21000000ul, 0x1000ul, 0ul, 0x32ul, -1, 0ul); > intptr_t res = 0; > res = syscall(__NR_io_setup, 3, 0x20000040ul); > if (res != -1) > r[0] = *(uint64_t*)0x20000040; > memcpy((void*)0x20000000, "/dev/nullb0\000", 12); > res = syscall(__NR_openat, 0xffffffffffffff9cul, 0x20000000ul, 0x24080ul, 0ul); > if (res != -1) > r[1] = res; > *(uint64_t*)0x20000400 = 0x20000140; > *(uint64_t*)0x20000140 = 0; > *(uint32_t*)0x20000148 = 0; > *(uint32_t*)0x2000014c = 0; > *(uint16_t*)0x20000150 = 0; > *(uint16_t*)0x20000152 = 0; > *(uint32_t*)0x20000154 = r[1]; > *(uint64_t*)0x20000158 = 0; > *(uint64_t*)0x20000160 = 0xfe00; > *(uint64_t*)0x20000168 = 0; > *(uint64_t*)0x20000170 = 0; > *(uint32_t*)0x20000178 = 0; > *(uint32_t*)0x2000017c = -1; > syscall(__NR_io_submit, r[0], 1ul, 0x20000400ul); > return 0; > } > > Thanks, > George >> >> One spot I don't like is how errors from bio_iov_iter_get_pages() >> are handled, will test it. >> >> diff --git a/block/fops.c b/block/fops.c >> index ad732a36f9b3..211f44974d1e 100644 >> --- a/block/fops.c >> +++ b/block/fops.c >> @@ -342,7 +342,7 @@ static ssize_t __blkdev_direct_IO_async(struct kiocb *iocb, >> if (unlikely(ret)) { >> bio->bi_status = BLK_STS_IOERR; >> bio_endio(bio); >> - return ret; >> + return -EIOCBQUEUED; >> } >> } >> dio->size = bio->bi_iter.bi_size; >> >> >
-- Pavel Begunkov
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