Re: ubiblock: null pointer dereference using scatterlist in work_queue

Stephan Wurm
2023-07-17T10:28:23Z

Richard,

Am 23-07-17 11:42 schrieb Richard Weinberger:
> Stephan,
>
> ----- Ursprüngliche Mail -----
> > Von: "Stephan Wurm" <stephan.wurm@a-eberle.de>
> > [ 26.127460] 8<--- cut here ---
> > [ 26.130689] Unable to handle kernel NULL pointer dereference at virtual
> > address 00000000
> > [ 26.138886] [00000000] *pgd=00000000
> > [ 26.142523] Internal error: Oops: 5 [#1] ARM
> > [ 26.146804] Modules linked in:
> > [ 26.149868] CPU: 0 PID: 18 Comm: kworker/0:3 Not tainted 6.1.38 #1
> > [ 26.156060] Hardware name: Freescale i.MX6 Quad/DualLite (Device Tree)
> > [ 26.162592] Workqueue: ubiblock0_2 ubiblock_do_work
> > [ 26.167498] PC is at ubi_io_read+0x78/0x2fc
> > [ 26.171693] LR is at ubi_eba_read_leb+0xe8/0x4a4
> > [ 26.176320] pc : [<c075f508>] lr : [<c075cd0c>] psr: 60070013
> > [ 26.182591] sp : f0961dc8 ip : 00000000 fp : 00002000
> > [ 26.187819] r10: c81c6000 r9 : 00000000 r8 : c81c7000
> > [ 26.193046] r7 : 00000200 r6 : 000008e0 r5 : 00002000 r4 : 00000000
> > [ 26.199578] r3 : 00000000 r2 : 00000000 r1 : 00000000 r0 : c81c6000
> > [ 26.206108] Flags: nZCv IRQs on FIQs on Mode SVC_32 ISA ARM Segment none
> > [ 26.213250] Control: 10c53c7d Table: 1824c059 DAC: 00000051
> > [ 26.218998] Register r0 information: slab kmalloc-8k start c81c6000 pointer
> > offset 0 size 8192
> > [ 26.227638] Register r1 information: NULL pointer
> > [ 26.232352] Register r2 information: NULL pointer
> > [ 26.237062] Register r3 information: NULL pointer
> > [ 26.241772] Register r4 information: NULL pointer
> > [ 26.246481] Register r5 information: non-paged memory
> > [ 26.251537] Register r6 information: non-paged memory
> > [ 26.256594] Register r7 information: non-paged memory
> > [ 26.261651] Register r8 information: slab kmalloc-8k start c81c6000 pointer
> > offset 4096 size 8192
> > [ 26.270545] Register r9 information: NULL pointer
> > [ 26.275254] Register r10 information: slab kmalloc-8k start c81c6000 pointer
> > offset 0 size 8192
> > [ 26.283977] Register r11 information: non-paged memory
> > [ 26.289120] Register r12 information: NULL pointer
> > [ 26.293916] Process kworker/0:3 (pid: 18, stack limit = 0x1a047662)
> > [ 26.300194] Stack: (0xf0961dc8 to 0xf0962000)
> > [ 26.304559] 1dc0: c1d50ec0 c075cc64 00000001 00000000
> > 00000000 c1d50ec0
> > [ 26.312744] 1de0: 00000001 24c676fe c075cc64 00000000 000008e0 c81c6000
> > c80c4000 00000000
> > [ 26.320928] 1e00: c1d50ec0 00000002 c81c7000 c075cd0c 00000200 c01d3930
> > 60070013 00000000
> > [ 26.329111] 1e20: 60070013 c1b43208 000008e0 24c676fe 00000000 c830f5cc
> > c830f5cc 00000200
> > [ 26.337294] 1e40: 00000000 00000001 00000200 c80c4000 00000000 c075d124
> > 00000000 00000200
> > [ 26.345477] 1e60: 00000000 c13e0ec0 c81c6000 c1d50ec0 00000000 00000000
> > 00000000 c80c4000
> > [ 26.353661] 1e80: c830f5cc c1e52c00 00000200 c81c6000 00000002 c075b748
> > 00000000 00000200
> > [ 26.361844] 1ea0: 00000000 c1312e58 ef7d3c00 0003e000 00000000 00000200
> > ef7d3c00 c1e52c00
> > [ 26.370027] 1ec0: c830f5a8 c830f5cc 00000000 c076b228 00000200 00000000
> > c830f500 c1d50ec0
> > [ 26.378211] 1ee0: c830f5d4 24c676fe c0c0e608 c830f5a8 c1ed3800 c1312e58
> > ef7d3c00 c1d50ec0
> > [ 26.386394] 1f00: 00000000 c14e59c0 ef7d3c05 c013c06c 00000001 00000000
> > c013bff4 00000000
> > [ 26.394577] 1f20: c1312e68 24c676fe c1b5f698 c19642b8 00000000 c101b390
> > 00000000 24c676fe
> > [ 26.402760] 1f40: c1d50ec0 c1ed3800 c1312e58 c1ed3818 c1312e94 c13dfc30
> > c1d50ec0 00000008
> > [ 26.410944] 1f60: c1312e58 c013c3f0 00000000 c1f16880 c1d50ec0 c013c3b0
> > c1ed3800 c1ed3880
> > [ 26.419126] 1f80: f095de9c 00000000 00000000 c0143654 c1f16880 c0143588
> > 00000000 00000000
> > [ 26.427309] 1fa0: 00000000 00000000 00000000 c0100128 00000000 00000000
> > 00000000 00000000
> > [ 26.435491] 1fc0: 00000000 00000000 00000000 00000000 00000000 00000000
> > 00000000 00000000
> > [ 26.443673] 1fe0: 00000000 00000000 00000000 00000000 00000013 00000000
> > 00000000 00000000
> > [ 26.451855] ubi_io_read from ubi_eba_read_leb+0xe8/0x4a4
> > [ 26.457277] ubi_eba_read_leb from ubi_eba_read_leb_sg+0x5c/0x154
> > [ 26.463390] ubi_eba_read_leb_sg from ubi_leb_read_sg+0x70/0xb0
> > [ 26.469325] ubi_leb_read_sg from ubiblock_do_work+0x104/0x238
> > [ 26.475180] ubiblock_do_work from process_one_work+0x238/0x57c
> > [ 26.481130] process_one_work from worker_thread+0x40/0x4f8
> > [ 26.486724] worker_thread from kthread+0xcc/0xf0
> > [ 26.491449] kthread from ret_from_fork+0x14/0x2c
> > [ 26.496168] Exception stack(0xf0961fb0 to 0xf0961ff8)
> > [ 26.501225] 1fa0: 00000000 00000000
> > 00000000 00000000
> > [ 26.509410] 1fc0: 00000000 00000000 00000000 00000000 00000000 00000000
> > 00000000 00000000
> > [ 26.517592] 1fe0: 00000000 00000000 00000000 00000000 00000013 00000000
> > [ 26.524215] Code: 1a000041 e59d2010 e1a09fc5 e1a0b005 (e5d23000)
> > [ 26.530367] ---[ end trace 0000000000000000 ]---
> >
> > This kernel Oops happens both on patched or vanilla kernels, of which we tried
> > several releases in 5.15.y and 6.1.y branches. We also tried with several of
> > our devices.
> > Upgrading to the latest mainline kernel did not work out-of-the-box, hence we
> > did not follow that track (yet).
> >
> > We tried with full debugging output for the whole ubi driver and used several
> > additional printks. That way we were able to see, that the first scatterlist
> > entry already pointed to virtual address zero when the first read request
> > caused by cryptsetup was added to ubiblock's work_queue.
> >
> > sg_virt(pdu->usgl.sg[0]) => page_address(sg) => 0x0000000
> >
> > We also tried to use hw_breakpoints to gather more information on (maybe)
> > another module interfering, but did not succeed (yet).
> >
> > But we were not able to narrow down the root cause until now.
> >
> >
> > As an additional twist, the system is able to boot when we mount the ubiblock
> > root filesystem without calling cryptsetup, hence skipping the dm-verity hash
> > verification. And we can verify the root filesystem with cryptsetup once the
> > system boot is finished.
> >
> > It is also possible to boot the same system image, including dm-verity, when
> > using a sdcard instead of the nand flash. Loading the FIT from sdcard but
> > calling cryptsetup on the ubiblock device again leads to the described oops.
> >
> >
> > Is there something we have overlooked?
> > Do you have further ideas to get behind this issue?
>
> So reading from ubiblock works as long you don't access it via dm-verity?
> How about other stacked devices such as dmcrypt?

We did not check other stacked devices, but we'll give this a try.

> Did you print the LEB number, read length and offset in ubiblock_read()?
> Maybe there is a bug related to setting up the correct device geometry
> and the read request is off.
Here is some excerpt from another try with KASAN enabled and full debug output:

[ 209.245803] UBI DBG wl (pid 1): found 4092 PEBs
[ 209.250945] UBI DBG eba (pid 1): initialize EBA sub-system
[ 209.257413] UBI DBG eba (pid 1): EBA sub-system is initialized
[ 209.352714] UBI DBG gen (pid 1): ubi0 major is 242
[ 209.361776] UBI DBG gen (pid 1): add volume 0
[ 209.368616] UBI DBG gen (pid 1): add volume 1
[ 209.375056] UBI DBG gen (pid 1): add volume 2
[ 209.381827] UBI DBG gen (pid 1): add volume 3
[ 209.388304] UBI DBG gen (pid 1): add volume 4
[ 209.398847] ubi0: attached mtd0 (name "nand", size 1024 MiB)
[ 209.404592] ubi0: PEB size: 262144 bytes (256 KiB), LEB size: 253952 bytes
[ 209.411626] ubi0: min./max. I/O unit sizes: 4096/4096, sub-page size 4096
[ 209.418668] ubi0: VID header offset: 4096 (aligned 4096), data offset: 8192
[ 209.425703] ubi0: good PEBs: 4092, bad PEBs: 4, corrupted PEBs: 0
[ 209.431931] ubi0: user volume: 5, internal volumes: 1, max. volumes count: 128
[ 209.439287] ubi0: max/mean erase counter: 56/30, WL threshold: 4096, image sequence number: 588826929
[ 209.448683] ubi0: available PEBs: 177, total reserved PEBs: 3915, PEBs reserved for bad PEB handling: 76
[ 209.458803] ubi0: background thread "ubi_bgt0d" started, PID 165
[ 209.465455] UBI DBG gen (pid 1): open device 0, volume root0, mode 1
[ 209.472714] UBI DBG gen (pid 1): open device 0, volume 2, mode 1
[ 209.480921] UBI DBG eba (pid 1): read 253952 bytes from offset 0 of LEB 2:0, PEB 3375
[ 209.499763] UBI DBG io (pid 1): read VID header from PEB 3375
[ 209.505581] UBI DBG io (pid 1): read 64 bytes from PEB 3375:4096
[ 209.512950] UBI DBG io (pid 1): read 253952 bytes from PEB 3375:8192
[ 209.540198] UBI DBG eba (pid 1): read 253952 bytes from offset 0 of LEB 2:1, PEB 3376
[ 209.548281] UBI DBG io (pid 1): read VID header from PEB 3376
[ 209.554096] UBI DBG io (pid 1): read 64 bytes from PEB 3376:4096
[ 209.560827] UBI DBG io (pid 1): read 253952 bytes from PEB 3376:8192
[ 209.587543] UBI DBG eba (pid 1): read 253952 bytes from offset 0 of LEB 2:2, PEB 3377

...

[ 291.514980] UBI DBG gen (pid 280): read 1024 bytes from offset 2048 of volume 2
[ 291.523198] UBI DBG eba (pid 280): read 1024 bytes from offset 2048 of LEB 2:0, PEB 3375
[ 291.541721] UBI DBG io (pid 280): read 1024 bytes from PEB 3375:10240
[ 291.549183] UBI DBG gen (pid 280): read 1024 bytes from offset 2097152 of volume 2
[ 291.557402] UBI DBG eba (pid 280): read 1024 bytes from offset 65536 of LEB 2:8, PEB 3383
[ 291.565881] UBI DBG io (pid 280): read 1024 bytes from PEB 3383:73728
[ 291.632851] UBI DBG gen (pid 280): release device 0, volume 2, mode 1
[ 291.639609] UBI DBG gen (pid 280): close device 0, volume 2, mode 1
realpath: /dev/disk/by-partuuid//dev/ubiblock0_2: No such file or directory
[ 293.065904] UBI DBG gen (pid 302): open device 0, volume 2, mode 1
[ 293.075832] UBI DBG gen (pid 18): read 512 bytes from LEB 2:0:0
[ 293.082685] UBI DBG eba (pid 18): read 512 bytes from offset 0 of LEB 2:0, PEB 3375
[ 293.208348] UBI DBG io (pid 18): read 512 bytes from PEB 3375:8192
[ 293.336418] ==================================================================
[ 293.343675] BUG: KASAN: null-ptr-deref in ubi_io_read+0x1d4/0x46c
[ 293.349822] Read of size 1 at addr 00000000 by task kworker/0:3/18
[ 293.356037]
[ 293.357551] CPU: 0 PID: 18 Comm: kworker/0:3 Not tainted 6.1.36 #1
[ 293.363774] Hardware name: Freescale i.MX6 Quad/DualLite (Device Tree)
[ 293.370331] Workqueue: ubiblock0_2 ubiblock_do_work
[ 293.375269] unwind_backtrace from show_stack+0x10/0x14
[ 293.380557] show_stack from dump_stack_lvl+0x34/0x48
[ 293.385668] dump_stack_lvl from kasan_report+0xb8/0xe8
[ 293.390956] kasan_report from ubi_io_read+0x1d4/0x46c
[ 293.396146] ubi_io_read from ubi_eba_read_leb+0x3c4/0x5cc
[ 293.401686] ubi_eba_read_leb from ubi_eba_read_leb_sg+0x84/0x1f8
[ 293.407831] ubi_eba_read_leb_sg from ubi_leb_read_sg+0xb4/0x110
[ 293.413891] ubi_leb_read_sg from ubiblock_do_work+0x180/0x390
[ 293.419779] ubiblock_do_work from process_one_work+0x46c/0x98c
[ 293.425763] process_one_work from worker_thread+0x7c/0x7a8
[ 293.431400] worker_thread from kthread+0x158/0x180
[ 293.436340] kthread from ret_from_fork+0x14/0x2c
[ 293.441094] Exception stack(0xf09a3fb0 to 0xf09a3ff8)
[ 293.446184] 3fa0: 00000000 00000000 00000000 00000000
[ 293.454402] 3fc0: 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000
[ 293.462616] 3fe0: 00000000 00000000 00000000 00000000 00000013 00000000
[ 293.469263] ==================================================================
[ 293.476593] Disabling lock debugging due to kernel taint
[ 293.481975] 8<--- cut here ---
[ 293.485057] Unable to handle kernel NULL pointer dereference at virtual address 00000000
[ 293.493209] [00000000] *pgd=00000000
[ 293.496837] Internal error: Oops: 5 [#1] ARM
[ 293.501141] Modules linked in:
[ 293.504232] CPU: 0 PID: 18 Comm: kworker/0:3 Tainted: G B 6.1.36 #1
[ 293.511927] Hardware name: Freescale i.MX6 Quad/DualLite (Device Tree)
[ 293.518481] Workqueue: ubiblock0_2 ubiblock_do_work
[ 293.523415] PC is at ubi_io_read+0x1d4/0x46c
[ 293.527729] LR is at kasan_report+0xc4/0xe8
[ 293.531948] pc : [<c11441d8>] lr : [<c030d198>] psr: 60070013
[ 293.538244] sp : f09a3b20 ip : 00000000 fp : 00000000
[ 293.543496] r10: c3581338 r9 : 00000200 r8 : 00002000
[ 293.548748] r7 : c3580f40 r6 : 00000d2f r5 : c3588000 r4 : c26631a0
[ 293.555305] r3 : 00000000 r2 : c3580f40 r1 : c1fd3240 r0 : 00000001
[ 293.561861] Flags: nZCv IRQs on FIQs on Mode SVC_32 ISA ARM Segment none
[ 293.569032] Control: 10c53c7d Table: 150dc059 DAC: 00000051
[ 293.574801] Register r0 information: non-paged memory
[ 293.579894] Register r1 information: non-slab/vmalloc memory
[ 293.585594] Register r2 information: slab task_struct start c3580f40 pointer offset 0
[ 293.593507] Register r3 information: NULL pointer
[ 293.598249] Register r4 information: non-slab/vmalloc memory
[ 293.603947] Register r5 information: slab kmalloc-8k start c3588000 pointer offset 0 size 8192
[ 293.612650] Register r6 information: non-paged memory
[ 293.617739] Register r7 information: slab task_struct start c3580f40 pointer offset 0
[ 293.625644] Register r8 information: non-paged memory
[ 293.630733] Register r9 information: non-paged memory
[ 293.635821] Register r10 information: slab task_struct start c3580f40 pointer offset 1016
[ 293.644075] Register r11 information: NULL pointer
[ 293.648905] Register r12 information: NULL pointer
[ 293.653732] Process kworker/0:3 (pid: 18, stack limit = 0xb1726ef2)
[ 293.660033] Stack: (0xf09a3b20 to 0xf09a4000)
[ 293.664434] 3b20: 00002000 00000200 c0a66714 f09a3b80 c3581590 f09a3bc0 c3589144 08e5cad6
[ 293.672653] 3b40: 41b58ab3 1e13476c c0a6feac 73395f12 f09a3fac c3580f40 c0100bd8 c3580f44
[ 293.680872] 3b60: 41b58ab3 c18a485c c1144004 c022c030 f09a3bf0 c115214c 60070013 ffffffff
[ 293.689089] 3b80: c147fc20 f09a3b70 c115214c 60070013 ffffffff c0100bd8 03d21031 03d21031
[ 293.697306] 3ba0: 00000001 000055b9 c168a0e0 60070013 00000000 00000000 f09a3ca0 c3580f40
[ 293.705523] 3bc0: 00000002 00000d2f c2447ed4 73395f12 c1152384 bd134788 c60c4800 c3588000
[ 293.713738] 3be0: 00000000 f09a3ca0 c3580f40 00000002 00000d2f c0a668d8 00000200 00000000
[ 293.721954] 3c00: 00000000 00000200 00000000 00000000 c3581338 00000006 00000007 c60c4af4
[ 293.730172] 3c20: c61700cc c0189714 c3580f40 c1b394b8 c3581590 00000000 16a24451 1866687e
[ 293.738389] 3c40: 41b58ab3 c18a4774 c0a66514 00000000 00000200 c3580f40 c1161810 c3580f44
[ 293.746606] 3c60: 00000d2f c1fc6940 c262e2a0 c022c030 00000001 60070013 c262e988 c262e980
[ 293.754823] 3c80: c262e988 60070013 60070013 c262e988 c262e980 c11617fc 00000000 73395f12
[ 293.763040] 3ca0: c262e980 c61700cc 00000200 00000000 00000200 c61700d0 00000001 00000000
[ 293.771256] 3cc0: 00000000 c0a66b64 00000000 00000200 00000000 c067f654 00000200 c3588000
[ 293.779472] 3ce0: c60c4800 00000000 c3580f40 c3581338 00000000 c60c4800 00000000 00000000
[ 293.787688] 3d00: 00000200 00000000 c61700cc c3588000 00000002 c1142ce4 00000000 00000200
[ 293.795904] 3d20: 00000000 efff6ea0 00000000 c3580f40 00000000 0003e000 00000200 c5becc00
[ 293.804120] 3d40: c61700a8 c61700cc 00000000 00000000 00000000 c0a764fc 00000200 00000000
[ 293.812337] 3d60: 41b58ab3 c182c6ac c018da1c 73395f12 600d0193 c6170000 c3580f40 bd1347b4
[ 293.820554] 3d80: 41b58ab3 c182c6d0 c018ddf8 c01843e8 00000001 0000aabf c35815a0 c01896c4
[ 293.828771] 3da0: 41b58ab3 c18a4dec c0a7637c c01896c4 c3580f40 c1b394b8 c3581590 00000000
[ 293.836989] 3dc0: c61700d4 ffffffff c1b2ace8 c01898c0 c5bedcc0 c5bedcb8 c3529a48 c3580f40
[ 293.845206] 3de0: c11617a4 c018e104 c1c2a0a0 c1fc6940 c1b2ace8 c022c030 00000001 73395f12
[ 293.853422] 3e00: c3529a00 c61700a8 c3529a00 c1b2acac e9761800 c1fc5f80 00000000 c3580f44
[ 293.861640] 3e20: c3529a0c c01537a8 00000001 00000000 c0153708 c0153e04 00000000 c3580f40
[ 293.869857] 3e40: e9761804 00000000 f09a3ea0 bd1347d0 c3529a14 c3529a10 e9761805 c3529a08
[ 293.878073] 3e60: c3529a04 c3529a24 c018ddf8 00000000 00000006 f09a3ee0 c3581590 00000000
[ 293.886291] 3e80: 41b58ab3 c18286f0 c015333c c01898c0 c0100bd8 c3580f44 c1c2a0a0 c3580f40
[ 293.894508] 3ea0: c2663320 c244b4f4 00000000 c1488f20 00000000 c022c030 00000000 c01896c4
[ 293.902725] 3ec0: c3580f40 c1b394b8 c3581590 00000000 ffffffff c018e104 c1b2acac c01898c0
[ 293.910942] 3ee0: ffffffff ffffffff 00000001 73395f12 c11617a4 c1b2acac c0153e04 c3580f40
[ 293.919160] 3f00: 00000008 c0153cc8 c3529a00 73395f12 c5b4ed74 c61700ac c3529a18 fffffd4a
[ 293.927378] 3f20: 00000008 c0153cc8 c3529a00 c1b2acac c61700a8 c0153d44 c1b2ace8 c1b2ace0
[ 293.935596] 3f40: c1b2ace4 c3529a34 c3580f40 c3529a24 c3529a20 c3529b00 c3529a1c c358114c
[ 293.943813] 3f60: 00000000 c3580f40 c3580f44 c1b09aac c3529b00 c0153cc8 c3529a00 00000000
[ 293.952028] 3f80: f099bd10 c015e298 00000000 c352b480 c015e140 00000000 00000000 00000000
[ 293.960242] 3fa0: 00000000 00000000 00000000 c0100128 00000000 00000000 00000000 00000000
[ 293.968457] 3fc0: 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000
[ 293.976670] 3fe0: 00000000 00000000 00000000 00000000 00000013 00000000 00000000 00000000
[ 293.984878] ubi_io_read from ubi_eba_read_leb+0x3c4/0x5cc
[ 293.990424] ubi_eba_read_leb from ubi_eba_read_leb_sg+0x84/0x1f8
[ 293.996572] ubi_eba_read_leb_sg from ubi_leb_read_sg+0xb4/0x110
[ 294.002631] ubi_leb_read_sg from ubiblock_do_work+0x180/0x390
[ 294.008519] ubiblock_do_work from process_one_work+0x46c/0x98c
[ 294.014506] process_one_work from worker_thread+0x7c/0x7a8
[ 294.020144] worker_thread from kthread+0x158/0x180
[ 294.025083] kthread from ret_from_fork+0x14/0x2c
[ 294.029836] Exception stack(0xf09a3fb0 to 0xf09a3ff8)
[ 294.034922] 3fa0: 00000000 00000000 00000000 00000000
[ 294.043136] 3fc0: 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000
[ 294.051348] 3fe0: 00000000 00000000 00000000 00000000 00000013 00000000
[ 294.057999] Code: 1a00008b eaffffee e1a0000b ebc724e1 (e5db3000)
[ 294.064308] ---[ end trace 0000000000000000 ]---

Thanks
--
Stephan Wurm <stephan.wurm@a-eberle.de>