Cramfs: "unable to handle kernel paging request" when reading a file from a fuzzed FS image

[Anatoly Trosinenko]

Hello,

When reading a file from a fuzzed cramfs image, unhandled kernel
paging request occurs.

How to reproduce with kvm-xfstests:
1) Checkout the v4.19 tag, copy x86_64-config-4.14 to .config, perform
`make olddefconfig`
2) Enable Cramfs in the config, then compile
3) In the `kvm-xfstests shell` perform:

root@kvm-xfstests:~# mount /vtmp
root@kvm-xfstests:~# mount /vtmp/cramfs.img /mnt
root@kvm-xfstests:~# cat /mnt/xyz
[   13.984751] BUG: unable to handle kernel paging request at 00000000bc4f563c
[   13.985476] PGD 8000000078767067 P4D 8000000078767067 PUD 0
[   13.986052] Oops: 0000 [#1] SMP PTI
[   13.986343] CPU: 0 PID: 367 Comm: cat Not tainted 4.19.0-xfstests #1
[   13.986861] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996),
BIOS 1.11.1-1ubuntu1 04/01/2014
[   13.987591] RIP: 0010:memcpy_erms+0x6/0x10
[   13.987930] Code: 90 90 90 90 eb 1e 0f 1f 00 48 89 f8 48 89 d1 48
c1 e9 03 83 e2 07 f3 48 a5 89 d1 f3 a4 c3 66 0f 1f 44 00 00 48 89 f8
48 89 d1 <f3> a4 c3 0f 1f 80 00 00 00 00 48 89 f8 48 83 fa 20 72 7e 40
38 fe
[   13.989446] RSP: 0018:ffff9acac0953c10 EFLAGS: 00010282
[   13.989876] RAX: ffff932677601000 RBX: ffff932677601000 RCX: 000000000000000d
[   13.990458] RDX: 000000000000000d RSI: 00000000bc4f563c RDI: ffff932677601000
[   13.991038] RBP: 000000000000000d R08: 00000000ffffffff R09: 00000000fffffffc
[   13.991620] R10: ffff93267bf23638 R11: 0000000000000000 R12: ffffc55241a1d038
[   13.992201] R13: 000000000000000d R14: ffff93267855d000 R15: 0000000000000ff3
[   13.992786] FS:  0000000000000000(0000) GS:ffff93267da00000(0063)
knlGS:00000000f7eec800
[   13.993443] CS:  0010 DS: 002b ES: 002b CR0: 0000000080050033
[   13.993913] CR2: 00000000bc4f563c CR3: 000000007853e004 CR4: 0000000000360ef0
[   13.994496] Call Trace:
[   13.994706]  cramfs_readpage+0x1ee/0x310
[   13.995032]  read_pages+0x128/0x170
[   13.995324]  __do_page_cache_readahead+0x2ba/0x2e0
[   13.995720]  ondemand_readahead+0x248/0x460
[   13.996066]  generic_file_buffered_read+0x494/0x700
[   13.996472]  __vfs_read+0x136/0x190
[   13.996846]  vfs_read+0x9f/0x130
[   13.997116]  ksys_read+0x52/0xc0
[   13.997386]  do_fast_syscall_32+0x9d/0x2f0
[   13.997725]  entry_SYSENTER_compat+0x84/0x96
[   13.998077] CR2: 00000000bc4f563c
[   13.998354] ---[ end trace 4763da97df55a7c9 ]---
[   13.998734] RIP: 0010:memcpy_erms+0x6/0x10
[   13.999072] Code: 90 90 90 90 eb 1e 0f 1f 00 48 89 f8 48 89 d1 48
c1 e9 03 83 e2 07 f3 48 a5 89 d1 f3 a4 c3 66 0f 1f 44 00 00 48 89 f8
48 89 d1 <f3> a4 c3 0f 1f 80 00 00 00 00 48 89 f8 48 83 fa 20 72 7e 40
38 fe
[   14.000584] RSP: 0018:ffff9acac0953c10 EFLAGS: 00010282
[   14.001011] RAX: ffff932677601000 RBX: ffff932677601000 RCX: 000000000000000d
[   14.001591] RDX: 000000000000000d RSI: 00000000bc4f563c RDI: ffff932677601000
[   14.002170] RBP: 000000000000000d R08: 00000000ffffffff R09: 00000000fffffffc
[   14.002750] R10: ffff93267bf23638 R11: 0000000000000000 R12: ffffc55241a1d038
[   14.003330] R13: 000000000000000d R14: ffff93267855d000 R15: 0000000000000ff3
[   14.003910] FS:  0000000000000000(0000) GS:ffff93267da00000(0063)
knlGS:00000000f7eec800
[   14.004569] CS:  0010 DS: 002b ES: 002b CR0: 0000000080050033
[   14.005037] CR2: 00000000bc4f563c CR3: 000000007853e004 CR4: 0000000000360ef0
[   14.005618] BUG: sleeping function called from invalid context at
include/linux/percpu-rwsem.h:34
[   14.006337] in_atomic(): 0, irqs_disabled(): 1, pid: 367, name: cat
[   14.006847] INFO: lockdep is turned off.
[   14.007172] irq event stamp: 1266
[   14.007448] hardirqs last  enabled at (1265): [<ffffffffba692cb9>]
_raw_spin_unlock_irq+0x29/0x40
[   14.008166] hardirqs last disabled at (1266): [<ffffffffb9e01574>]
trace_hardirqs_off_thunk+0x1a/0x1c
[   14.008916] softirqs last  enabled at (0): [<ffffffffb9e8329a>]
copy_process.part.6+0x76a/0x1ec0
[   14.009628] softirqs last disabled at (0): [<0000000000000000>]
      (null)
[   14.010229] CPU: 0 PID: 367 Comm: cat Tainted: G      D
4.19.0-xfstests #1
[   14.010857] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996),
BIOS 1.11.1-1ubuntu1 04/01/2014
[   14.011582] Call Trace:
[   14.011790]  dump_stack+0x85/0xc0
[   14.012067]  ___might_sleep.cold.13+0xac/0xbc
[   14.012436]  exit_signals+0x1c/0x200
[   14.012733]  do_exit+0xac/0xb00
[   14.012996]  ? ksys_read+0x52/0xc0
[   14.013279]  rewind_stack_do_exit+0x17/0x20
Killed
root@kvm-xfstests:~#

Best regards
Anatoly

Attachment: cramfs.img
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Attachment: cramfs.img.orig
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