Bug details
Title: Linux 2.6.x zlib_inflate memory corruption
Description: Linux 2.6.x zlib_inflate function can be abused by filesystems that depend on zlib compression, such as cramfs. A failure to handle crafted data, result of a read operation in a corrupted filesystem stream, may lead to memory corruption. This particular vulnerability requires a filesystem (proof of concept for cramfs provided) to fail validation (ex. no integrity checking) of the binary stream in order to reach execution of zlib_inflate().
Proof of concept or exploit: The following cramfs filesystem image can be used to reproduce the bug: MOKB-07-11-2006.img.bz2
Use a loopback device to mount it: bunzip2 MOKB-07-11-2006.img.bz2 && mount -t cramfs -o loop MOKB-07-11-2006.iso /media/test && cat /media/test/* 2>/dev/null 1>&2
Debugging information:

The bug has been found using the Linux version of fsfuzzer on a Fedora Core 6 installation, with up to date packages as of 07-11-2006. A read operation is necessary to trigger the bug. The architecture used to conduct the tests is IA32/x86, SMP enabled.

Related debugging information:

[root@fedora ~]# crash /usr/lib/debug/lib/modules/2.6.18-1.2798.fc6/vmlinux /var/crash/2006-11-07-22\:13/vmcore

crash 4.0-3.3
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      KERNEL: /usr/lib/debug/lib/modules/2.6.18-1.2798.fc6/vmlinux
    DUMPFILE: /var/crash/2006-11-07-22:13/vmcore
        CPUS: 1
        DATE: Tue Nov  7 22:12:32 2006
      UPTIME: 00:03:01
LOAD AVERAGE: 0.68, 0.46, 0.20
       TASKS: 61
    NODNAE: fedora
     RELEASE: 2.6.18-1.2798.fc6
     VERSION: #1 SMP Mon Oct 16 14:37:32 EDT 2006
     MACHINE: i686  (2799 Mhz)
      MEMORY: 256 MB
       PANIC: "Oops: 0000 [#1]" (check log for details)
         PID: 1976
     COMMAND: "bash"
        TASK: cfd863b0  [THREAD_INFO: cb6d9000]
         CPU: 0

crash> log
SELinux: initialized (dev loop0, type cramfs), uses genfs_contexts
Error -3 while decompressing!
Error -3 while decompressing!
Error -3 while decompressing!
Error -3 while decompressing!
Error -3 while decompressing!
BUG: unable to handle kernel paging request at virtual address db5b0c28 <---------- edx
 printing eip:
*pde = 00000000
Oops: 0000 [#1]
last sysfs file: /block/loop3/range
Modules linked in: cramfs loop ipv6 sunrpc ip_conntrack_netbios_ns ipt_REJECT xt_state ip_conntrack
nfnetlink xt_tcpudp iptable_filter ip_tables x_tables video sbs i2c_ec button battery asus_acpi ac
parport_pc lp parport floppy snd_ens1371 gameport snd_rawmidi snd_ac97_codec snd_ac97_bus snd_seq_dummy
snd_seq_oss snd_seq_midi_event snd_seq sg snd_seq_device snd_pcm_oss snd_mixer_oss snd_pcm snd_timer
i2c_piix4 snd soundcore snd_page_alloc i2c_core pcspkr vmxnet(U) pcnet32 mii ide_cd serio_raw cdrom
dm_snapshot dm_zero dm_mirror dm_mod ext3 jbd mptspi scsi_transport_spi mptscsih sd_mod scsi_mod
CPU:    0
EIP:    0060:[]    Tainted: P      VLI
EFLAGS: 00010286   (2.6.18-1.2798.fc6 #1)
EIP is at zlib_inflate+0xf8/0x148d
eax: 00000000   ebx: 00000000   ecx: db5b0c28   edx: d0af7000
esi: cb6c2000   edi: db5b0c28   ebp: f553ca78   esp: cb7dec58
ds: 007b   es: 007b   ss: 0068
Process cat (pid: 1946, ti=cb7de000 task=cf88b670 task.ti=cb7de000)
Stack: c07dc77e 00000000 d0af56c0 00000000 cb0e0000 00000007 00000000 00000121
       00000005 d0af56c0 d0af7000 cb7dec90 00000000 db5b0c28 cb6c2000 f553ca77
       00001000 00000000 00000000 cb7decc8 00001000 00000000 00000121 c04c1353
Call Trace:
 [] cramfs_uncompress_block+0x6e/0xb2 [cramfs]
 [] cramfs_readpage+0xc8/0x123 [cramfs]
 [] __do_page_cache_readahead+0x16f/0x1c8
 [] blockable_page_cache_readahead+0x4c/0x9f
 [] page_cache_readahead+0xbf/0x196
 [] do_generic_mapping_read+0x13d/0x49b
 [] __generic_file_aio_read+0x18c/0x1d1
 [] generic_file_read+0xa2/0xb8
 [] vfs_read+0xa6/0x157
 [] sys_read+0x41/0x67
 [] syscall_call+0x7/0xb
DWARF2 unwinder stuck at syscall_call+0x7/0xb
Leftover inexact backtrace:
Code: ff e9 07 10 00 00 8b 54 24 28 83 7a 08 00 75 31 c7 02 0c 00 00 00 eb be 83 7c 24 3c 00 0f 84 ea 0f 00 00 8b 4c
24 34 ff 4c 24 3c <0f> b6 01 8a 4c 24 48 ff 44 24 34 83 44 24
48 08 d3 e0 01 44 24
EIP: [] zlib_inflate+0xf8/0x148d SS:ESP 0068:cb7dec58
 <3>BUG: sleeping function called from invalid context at kernel/rwsem.c:20
in_atomic():0, irqs_disabled():1
 [] dump_trace+0x69/0x1af
 [] show_trace_log_lvl+0x18/0x2c
 [] show_trace+0xf/0x11
 [] dump_stack+0x15/0x17
 [] down_read+0x12/0x20
 [] blocking_notifier_call_chain+0xe/0x29
 [] do_exit+0x1b/0x776
 [] die+0x29d/0x2c2
 [] do_page_fault+0x408/0x4db
 [] error_code+0x39/0x40
DWARF2 unwinder stuck at error_code+0x39/0x40
Leftover inexact backtrace:
 [] zlib_inflate+0xf8/0x148d
 [] inode_has_perm+0x5b/0x63
 [] __rmqueue+0x32/0xa2
 [] cramfs_uncompress_block+0x6e/0xb2 [cramfs]
 [] cramfs_readpage+0xc8/0x123 [cramfs]
 [] __do_page_cache_readahead+0x16f/0x1c8
 [] blockable_page_cache_readahead+0x4c/0x9f
 [] page_cache_readahead+0xbf/0x196
 [] do_generic_mapping_read+0x13d/0x49b
 [] __generic_file_aio_read+0x18c/0x1d1
 [] file_read_actor+0x0/0xe0
 [] generic_file_read+0x0/0xb8
 [] generic_file_read+0xa2/0xb8
 [] autoremove_wake_function+0x0/0x35
 [] vfs_read+0xa6/0x157
 [] sys_read+0x41/0x67
 [] syscall_call+0x7/0xb
SysRq : Trigger a crashdump

crash> mount
c92537c0 c9258000 rootfs rootfs        /
c9253cc0 cfb38600 ext3   /dev/root     /
c9253c40 cfdc9600 tmpfs  /dev          /dev
c9253bc0 cfd03a00 proc   /proc         /proc
c9253b40 c9258200 sysfs  /sys          /sys
c9253e40 cfe2a800 selinuxfs none          /selinux
c9253ec0 cee5d800 usbfs  /proc/bus/usb /proc/bus/usb
c92530c0 cfe25400 devpts devpts        /dev/pts
c92538c0 cffb0000 ext3   /dev/sda1     /boot
c9253940 cffc2000 tmpfs  tmpfs         /dev/shm
c92539c0 cffb1a00 binfmt_misc none          /proc/sys/fs/binfmt_misc
c9253dc0 cffb0400 rpc_pipefs sunrpc        /var/lib/nfs/rpc_pipefs
c9253a40 cee5d000 cramfs /dev/loop0    /media/test
crash> x/10 0xc04ea58b
0xc04ea58b :  0x8a01b60f      0xff48244c      0x83342444      0x08482444
0xc04ea59b :  0x4401e0d3      0x7c834424      0x760f4824      0x44b60fd0
0xc04ea5ab :  0x548b4424      0xe0c14424
crash> x/10 0xdb5b0c28  <---------- edx
0xdb5b0c28:     gdb: invalid kernel virtual address: db5b0c28  type: "gdb_readmem callback"
crash> ascii db5b0c28   <---------- edx
db5b0c28: ([
crash> rd  0xcb6c2000 50
cb6c2000:  2d77722d 722d2d72 20202d2d 746f6f72   -rw-r--r--  root
cb6c2010:  6f6f7220 79732074 6d657473 6f3a755f    root system_u:o
cb6c2020:  63656a62 3a725f74 666d6f72 20745f73   bject_r:romfs_t
cb6c2030:  20202020 43202020 4959504f 6c0a474e          COPYING.l
cb6c2040:  72787772 77727877 72202078 20746f6f   rwxrwxrwx  root
cb6c2050:  746f6f72 73797320 5f6d6574 626f3a75   root system_u:ob
cb6c2060:  7463656a 723a725f 73666d6f 2020745f   ject_r:romfs_t
cb6c2070:  20202020 4f432020 4e495950 2d0a3247         COPYING2.-
cb6c2080:  722d7772 2d722d2d 7220202d 20746f6f   rw-r--r--  root
cb6c2090:  746f6f72 73797320 5f6d6574 626f3a75   root system_u:ob
cb6c20a0:  7463656a 723a725f 73666d6f 2020745f   ject_r:romfs_t
cb6c20b0:  20202020 72632020 73666d61 7361622e         cramfs.bas
cb6c20c0:  722d0a65 2d727877                     e.-rwxr-
crash> kmem 0xd0af7000
cb7ff7e0   d0af7000 - d0b03000   49152

c9161800   b0c0000   -------    -----   1 80000000