2.6.22-rc6-mm1-cfs-v19 Unable to handle kernel NULL pointer dereference (reproducable)

2.6.22-rc6-mm1-cfs-v19 Unable to handle kernel NULL pointer dereference (reproducable)

[Markus Trippelsdorf]

Just got this oops while I was updating my system:

Unable to handle kernel NULL pointer dereference at 00000000000002a6 RIP:
 [<ffffffff802861b6>] vfs_permission+0x6/0x10
PGD 120f9067 PUD 4f5ec067 PMD 0
Oops: 0000 [1] SMP
CPU 0
Pid: 14067, comm: touch Not tainted 2.6.22-rc6-mm1-cfs-v19 #7
RIP: 0010:[<ffffffff802861b6>]  [<ffffffff802861b6>] vfs_permission+0x6/0x10
RSP: 0018:ffff8100083a7e20  EFLAGS: 00010293
RAX: 0000000000000296 RBX: 0000000000000000 RCX: ffff81001cb6ee00
RDX: ffff8100083a7e28 RSI: 0000000000000002 RDI: ffff8100083a7e28
RBP: 00000000fffffff3 R08: 0000000000000002 R09: 00002b70e16872b8
R10: 0000000000000000 R11: 0000000000000246 R12: ffff81001cb6ee00
R13: ffff81006396e828 R14: ffff81000c35da28 R15: 0000000000000002
FS:  00002b70e23fbd10(0000) GS:ffffffff8061b000(0000) knlGS:00000000f6ca96c0
CS:  0010 DS: 0000 ES: 0000 CR0: 000000008005003b
CR2: 00000000000002a6 CR3: 000000001ca29000 CR4: 00000000000006e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400
Process touch (pid: 14067, threadinfo ffff8100083a6000, task ffff81001c589620)
Stack:  ffffffff802a15e0 0000000000000296 ffffffff8021d9c0 00000000000001b6
 ffff81001cb6ee00 ffff81006396e828 0000000000000000 00002b70e1d66850
 0000000000000004 ffff8100083a7f58 ffff81001c589620 0000000000000000
Call Trace:
 [<ffffffff802a15e0>] do_utimes+0x230/0x250
 [<ffffffff8021d9c0>] do_page_fault+0x420/0x8a0
 [<ffffffff8027ca8a>] do_filp_open+0x3a/0x50
 [<ffffffff802a1707>] sys_utimensat+0x37/0xe0
 [<ffffffff8051bb8d>] error_exit+0x0/0x84
 [<ffffffff8020bc5e>] system_call+0x7e/0x83


Code: 48 8b 78 10 e9 d1 fd ff ff 90 53 48 89 fb 48 8d bf b4 00 00
RIP  [<ffffffff802861b6>] vfs_permission+0x6/0x10
 RSP <ffff8100083a7e20>
CR2: 00000000000002a6

I was running the »paludis« package manager: 

make[1]: Leaving directory `/var/tmp/paludis/sys-libs/gpm-1.20.1-r6/work/gpm-1.20.1/contrib'
>>> Done src_compile
>>> Skipping src_test (SKIP_FUNCTIONS)
>>> Starting builtin_saveenv
>>> Done builtin_saveenv
>>> Completed ebuild phases loadenv unpack compile test saveenv
>>> Running ebuild phases loadenv install saveenv as root:root...
>>> Starting builtin_loadenv
>>> Done builtin_loadenv
>>> Starting src_install
touch src/.depend # to prevent unecessary warnings
make: *** [dep] Killed

Running "touch  /var/tmp/paludis/sys-libs/gpm-1.20.1-r6/work/gpm-1.20.1/src/.depend" 
triggers this oops.

Full dmesg follows:

Linux version 2.6.22-rc6-mm1-cfs-v19 (root@gentoox2.trippelsdorf.de) (gcc version 4.2.0 (Gentoo 4.2.0)) #7 SMP Fri Jul 6 22:08:21 CEST 2007
Command line: root=/dev/sda1
BIOS-provided physical RAM map:
 BIOS-e820: 0000000000000000 - 000000000009fc00 (usable)
 BIOS-e820: 000000000009fc00 - 00000000000a0000 (reserved)
 BIOS-e820: 00000000000e4000 - 0000000000100000 (reserved)
 BIOS-e820: 0000000000100000 - 000000007ffb0000 (usable)
 BIOS-e820: 000000007ffb0000 - 000000007ffc0000 (ACPI data)
 BIOS-e820: 000000007ffc0000 - 000000007fff0000 (ACPI NVS)
 BIOS-e820: 000000007fff0000 - 0000000080000000 (reserved)
 BIOS-e820: 00000000ff780000 - 0000000100000000 (reserved)
Entering add_active_range(0, 0, 159) 0 entries of 256 used
Entering add_active_range(0, 256, 524208) 1 entries of 256 used
end_pfn_map = 1048576
DMI 2.3 present.
ACPI: RSDP 000FA7C0, 0021 (r2 ACPIAM)
ACPI: XSDT 7FFB0100, 003C (r1 A M I  OEMXSDT  11000514 MSFT       97)
ACPI: FACP 7FFB0290, 00F4 (r3 A M I  OEMFACP  11000514 MSFT       97)
ACPI: DSDT 7FFB03F0, 3A3E (r1  A0036 A0036001        1 MSFT  100000D)
ACPI: FACS 7FFC0000, 0040
ACPI: APIC 7FFB0390, 0052 (r1 A M I  OEMAPIC  11000514 MSFT       97)
ACPI: OEMB 7FFC0040, 003F (r1 A M I  OEMBIOS  11000514 MSFT       97)
Entering add_active_range(0, 0, 159) 0 entries of 256 used
Entering add_active_range(0, 256, 524208) 1 entries of 256 used
sizeof(struct page) = 56
Zone PFN ranges:
  DMA             0 ->     4096
  DMA32        4096 ->  1048576
  Normal    1048576 ->  1048576
Movable zone start PFN for each node
early_node_map[2] active PFN ranges
    0:        0 ->      159
    0:      256 ->   524208
On node 0 totalpages: 524111
Node 0 memmap at 0xffff810001000000 size 29360128 first pfn 0xffff810001000000
  DMA zone: 56 pages used for memmap
  DMA zone: 1200 pages reserved
  DMA zone: 2743 pages, LIFO batch:0
  DMA32 zone: 7110 pages used for memmap
  DMA32 zone: 513002 pages, LIFO batch:31
  Normal zone: 0 pages used for memmap
  Movable zone: 0 pages used for memmap
ACPI: PM-Timer IO Port: 0x808
ACPI: Local APIC address 0xfee00000
ACPI: LAPIC (acpi_id[0x01] lapic_id[0x00] enabled)
Processor #0 (Bootup-CPU)
ACPI: LAPIC (acpi_id[0x02] lapic_id[0x01] enabled)
Processor #1
ACPI: IOAPIC (id[0x02] address[0xfec00000] gsi_base[0])
IOAPIC[0]: apic_id 2, address 0xfec00000, GSI 0-23
ACPI: INT_SRC_OVR (bus 0 bus_irq 0 global_irq 2 dfl dfl)
ACPI: IRQ0 used by override.
ACPI: IRQ2 used by override.
ACPI: IRQ9 used by override.
Setting APIC routing to flat
Using ACPI (MADT) for SMP configuration information
Allocating PCI resources starting at 88000000 (gap: 80000000:7f780000)
PERCPU: Allocating 22336 bytes of per cpu data
Built 1 zonelists in Zone order, mobility grouping on.  Total pages: 515745
Kernel command line: root=/dev/sda1
Initializing CPU#0
PID hash table entries: 4096 (order: 12, 32768 bytes)
Extended CMOS year: 2000
TSC calibrated against PM_TIMER
Marking TSC unstable due to TSCs unsynchronized
time.c: Detected 2400.689 MHz processor.
Console: colour VGA+ 80x25
console [tty0] enabled
Dentry cache hash table entries: 262144 (order: 9, 2097152 bytes)
Inode-cache hash table entries: 131072 (order: 8, 1048576 bytes)
Checking aperture...
CPU 0: aperture @ e0000000 size 128 MB
Memory: 2059452k/2096832k available (3195k kernel code, 36748k reserved, 1004k data, 220k init)
SLUB: Genslabs=22, HWalign=64, Order=0-3, MinObjects=16, CPUs=2, Nodes=1
Calibrating delay using timer specific routine.. 4805.13 BogoMIPS (lpj=2402565)
kswapd reclaim order set to 3
Mount-cache hash table entries: 256
CPU: L1 I Cache: 64K (64 bytes/line), D cache 64K (64 bytes/line)
CPU: L2 Cache: 512K (64 bytes/line)
CPU: Physical Processor ID: 0
CPU: Processor Core ID: 0
Freeing SMP alternatives: 26k freed
ACPI: Core revision 20070126
Using local APIC timer interrupts.
Booting processor 1/2 APIC 0x1
Initializing CPU#1
Calibrating delay using timer specific routine.. 4800.38 BogoMIPS (lpj=2400193)
CPU: L1 I Cache: 64K (64 bytes/line), D cache 64K (64 bytes/line)
CPU: L2 Cache: 512K (64 bytes/line)
CPU: Physical Processor ID: 0
CPU: Processor Core ID: 1
AMD Athlon(tm) 64 X2 Dual Core Processor 3800+ stepping 01
Brought up 2 CPUs
NET: Registered protocol family 16
ACPI: bus type pci registered
PCI: Using configuration type 1
ACPI: Interpreter enabled
ACPI: Using IOAPIC for interrupt routing
ACPI: PCI Root Bridge [PCI0] (0000:00)
PCI: Probing PCI hardware (bus 00)
Force enabled HPET at base address 0xfed00000
PCI: enabled onboard AC97/MC97 devices
ACPI: PCI Interrupt Routing Table [\_SB_.PCI0._PRT]
ACPI: PCI Interrupt Link [LNKA] (IRQs 3 4 5 7 10 *11 14 15)
ACPI: PCI Interrupt Link [LNKB] (IRQs 3 4 5 7 *10 11 14 15)
ACPI: PCI Interrupt Link [LNKC] (IRQs 3 4 *5 7 10 11 14 15)
ACPI: PCI Interrupt Link [LNKD] (IRQs *3 4 5 7 10 11 14 15)
ACPI: PCI Interrupt Link [LNKE] (IRQs 3 4 5 7 10 11 14 15) *0, disabled.
ACPI: PCI Interrupt Link [LNKF] (IRQs 3 4 5 7 10 11 14 15) *0, disabled.
ACPI: PCI Interrupt Link [LNKG] (IRQs 3 4 5 7 10 11 14 15) *0, disabled.
ACPI: PCI Interrupt Link [LNKH] (IRQs 3 4 5 7 10 11 14 15) *0, disabled.
ACPI Warning (tbutils-0158): Incorrect checksum in table [OEMB] -  BC, should be BB [20070126]
Linux Plug and Play Support v0.97 (c) Adam Belay
pnp: PnP ACPI init
ACPI: bus type pnp registered
pnp: PnP ACPI: found 10 devices
ACPI: ACPI bus type pnp unregistered
SCSI subsystem initialized
libata version 2.21 loaded.
usbcore: registered new interface driver usbfs
usbcore: registered new interface driver hub
usbcore: registered new device driver usb
PCI: Using ACPI for IRQ routing
PCI: If a device doesn't work, try "pci=routeirq".  If it helps, post a report
PCI: Cannot allocate resource region 0 of device 0000:00:00.0
agpgart: Detected AGP bridge 0
agpgart: AGP aperture is 128M @ 0xe0000000
pnp: 00:05: ioport range 0x680-0x6ff has been reserved
pnp: 00:05: ioport range 0x290-0x297 has been reserved
pnp: 00:07: iomem range 0xfec00000-0xfec00fff has been reserved
pnp: 00:07: iomem range 0xfee00000-0xfee00fff could not be reserved
pnp: 00:07: iomem range 0xfff80000-0xffffffff could not be reserved
pnp: 00:09: iomem range 0x0-0x9ffff could not be reserved
pnp: 00:09: iomem range 0xc0000-0xdffff has been reserved
Time: hpet clocksource has been installed.
Switched to high resolution mode on CPU 0
Switched to high resolution mode on CPU 1
pnp: 00:09: iomem range 0xe0000-0xfffff could not be reserved
pnp: 00:09: iomem range 0x100000-0x7ffeffff could not be reserved
PCI: Bridge: 0000:00:01.0
  IO window: e000-efff
  MEM window: fbd00000-fbffffff
  PREFETCH window: e8000000-faffffff
PCI: Setting latency timer of device 0000:00:01.0 to 64
NET: Registered protocol family 2
IP route cache hash table entries: 65536 (order: 7, 524288 bytes)
TCP established hash table entries: 131072 (order: 9, 3145728 bytes)
TCP bind hash table entries: 65536 (order: 8, 1048576 bytes)
TCP: Hash tables configured (established 131072 bind 65536)
TCP reno registered
SGI XFS with large block/inode numbers, no debug enabled
io scheduler noop registered
io scheduler anticipatory registered
io scheduler deadline registered
io scheduler cfq registered (default)
PCI: VIA PCI bridge detected. Disabling DAC.
Boot video device is 0000:01:00.0
ACPI: PCI Interrupt 0000:01:00.0[A] -> GSI 16 (level, low) -> IRQ 16
radeonfb: Found Intel x86 BIOS ROM Image
radeonfb: Retrieved PLL infos from BIOS
radeonfb: Reference=27.00 MHz (RefDiv=12) Memory=240.00 Mhz, System=166.00 MHz
radeonfb: PLL min 20000 max 40000
i2c-adapter i2c-2: unable to read EDID block.
i2c-adapter i2c-2: unable to read EDID block.
i2c-adapter i2c-2: unable to read EDID block.
i2c-adapter i2c-3: unable to read EDID block.
i2c-adapter i2c-3: unable to read EDID block.
i2c-adapter i2c-3: unable to read EDID block.
radeonfb: Monitor 1 type DFP found
radeonfb: EDID probed
radeonfb: Monitor 2 type no found
Console: switching to colour frame buffer device 210x65
radeonfb (0000:01:00.0): ATI Radeon Y` 
input: Power Button (FF) as /devices/virtual/input/input0
ACPI: Power Button (FF) [PWRF]
input: Power Button (CM) as /devices/virtual/input/input1
ACPI: Power Button (CM) [PWRB]
input: Sleep Button (CM) as /devices/virtual/input/input2
ACPI: Sleep Button (CM) [SLPB]
Real Time Clock Driver v1.12ac
Linux agpgart interface v0.102 (c) Dave Jones
[drm] Initialized drm 1.1.0 20060810
[drm] Initialized radeon 1.27.0 20060524 on minor 0
loop: module loaded
r8169 Gigabit Ethernet driver 2.2LK loaded
ACPI: PCI Interrupt 0000:00:0e.0[A] -> GSI 19 (level, low) -> IRQ 19
PCI: Disallowing DAC for device 0000:00:0e.0
eth0: RTL8169s/8110s at 0xffffc2000001a000, 00:08:54:36:f2:2f, IRQ 19
sata_via 0000:00:0f.0: version 2.2
ACPI: PCI Interrupt 0000:00:0f.0[B] -> GSI 20 (level, low) -> IRQ 20
sata_via 0000:00:0f.0: routed to hard irq line 10
scsi0 : sata_via
scsi1 : sata_via
ata1: SATA max UDMA/133 cmd 0x000000000001c800 ctl 0x000000000001c402 bmdma 0x000000000001b400 irq 0
ata2: SATA max UDMA/133 cmd 0x000000000001c000 ctl 0x000000000001b802 bmdma 0x000000000001b408 irq 0
ata1: SATA link up 1.5 Gbps (SStatus 113 SControl 300)
ata1.00: ATA-7: SAMSUNG HD401LJ, ZZ100-15, max UDMA7
ata1.00: 781422768 sectors, multi 16: LBA48 NCQ (depth 0/32)
ata1.00: configured for UDMA/133
ata2: SATA link down 1.5 Gbps (SStatus 0 SControl 300)
scsi 0:0:0:0: Direct-Access     ATA      SAMSUNG HD401LJ  ZZ10 PQ: 0 ANSI: 5
sd 0:0:0:0: [sda] 781422768 512-byte hardware sectors (400088 MB)
sd 0:0:0:0: [sda] Write Protect is off
sd 0:0:0:0: [sda] Mode Sense: 00 3a 00 00
sd 0:0:0:0: [sda] Write cache: enabled, read cache: enabled, doesn't support DPO or FUA
sd 0:0:0:0: [sda] 781422768 512-byte hardware sectors (400088 MB)
sd 0:0:0:0: [sda] Write Protect is off
sd 0:0:0:0: [sda] Mode Sense: 00 3a 00 00
sd 0:0:0:0: [sda] Write cache: enabled, read cache: enabled, doesn't support DPO or FUA
 sda: sda1 sda2 sda3 sda4
sd 0:0:0:0: [sda] Attached SCSI disk
sd 0:0:0:0: Attached scsi generic sg0 type 0
pata_via 0000:00:0f.1: version 0.3.1
ACPI: PCI Interrupt 0000:00:0f.1[A] -> GSI 20 (level, low) -> IRQ 20
scsi2 : pata_via
scsi3 : pata_via
ata3: PATA max UDMA/133 cmd 0x00000000000101f0 ctl 0x00000000000103f6 bmdma 0x000000000001fc00 irq 14
ata4: PATA max UDMA/133 cmd 0x0000000000010170 ctl 0x0000000000010376 bmdma 0x000000000001fc08 irq 15
ata4.00: ATAPI: LITE-ON DVDRW SHW-16H5S, LS0R, max UDMA/66
ata4.00: limited to UDMA/33 due to 40-wire cable
ata4.00: configured for UDMA/33
scsi 3:0:0:0: CD-ROM            LITE-ON  DVDRW SHW-16H5S  LS0R PQ: 0 ANSI: 5
sr0: scsi3-mmc drive: 48x/48x writer cd/rw xa/form2 cdda tray
Uniform CD-ROM driver Revision: 3.20
sr 3:0:0:0: Attached scsi CD-ROM sr0
sr 3:0:0:0: Attached scsi generic sg1 type 5
ACPI: PCI Interrupt 0000:00:10.4[C] -> GSI 21 (level, low) -> IRQ 21
ehci_hcd 0000:00:10.4: EHCI Host Controller
ehci_hcd 0000:00:10.4: new USB bus registered, assigned bus number 1
ehci_hcd 0000:00:10.4: irq 21, io mem 0xfbc00000
ehci_hcd 0000:00:10.4: USB 2.0 started, EHCI 1.00, driver 10 Dec 2004
usb usb1: new device found, idVendor=0000, idProduct=0000
usb usb1: new device strings: Mfr=3, Product=2, SerialNumber=1
usb usb1: Product: EHCI Host Controller
usb usb1: Manufacturer: Linux 2.6.22-rc6-mm1-cfs-v19 ehci_hcd
usb usb1: SerialNumber: 0000:00:10.4
usb usb1: configuration #1 chosen from 1 choice
hub 1-0:1.0: USB hub found
hub 1-0:1.0: 4 ports detected
USB Universal Host Controller Interface driver v3.0
ACPI: PCI Interrupt 0000:00:10.0[A] -> GSI 21 (level, low) -> IRQ 21
uhci_hcd 0000:00:10.0: UHCI Host Controller
uhci_hcd 0000:00:10.0: new USB bus registered, assigned bus number 2
uhci_hcd 0000:00:10.0: irq 21, io base 0x0000d000
usb usb2: new device found, idVendor=0000, idProduct=0000
usb usb2: new device strings: Mfr=3, Product=2, SerialNumber=1
usb usb2: Product: UHCI Host Controller
usb usb2: Manufacturer: Linux 2.6.22-rc6-mm1-cfs-v19 uhci_hcd
usb usb2: SerialNumber: 0000:00:10.0
usb usb2: configuration #1 chosen from 1 choice
hub 2-0:1.0: USB hub found
hub 2-0:1.0: 2 ports detected
ACPI: PCI Interrupt 0000:00:10.1[A] -> GSI 21 (level, low) -> IRQ 21
uhci_hcd 0000:00:10.1: UHCI Host Controller
uhci_hcd 0000:00:10.1: new USB bus registered, assigned bus number 3
uhci_hcd 0000:00:10.1: irq 21, io base 0x0000d400
usb usb3: new device found, idVendor=0000, idProduct=0000
usb usb3: new device strings: Mfr=3, Product=2, SerialNumber=1
usb usb3: Product: UHCI Host Controller
usb usb3: Manufacturer: Linux 2.6.22-rc6-mm1-cfs-v19 uhci_hcd
usb usb3: SerialNumber: 0000:00:10.1
usb usb3: configuration #1 chosen from 1 choice
hub 3-0:1.0: USB hub found
hub 3-0:1.0: 2 ports detected
usb 2-1: new low speed USB device using uhci_hcd and address 2
usb 2-1: new device found, idVendor=046a, idProduct=0021
usb 2-1: new device strings: Mfr=0, Product=0, SerialNumber=0
usb 2-1: configuration #1 chosen from 1 choice
usb 3-1: new low speed USB device using uhci_hcd and address 2
usb 3-1: new device found, idVendor=046d, idProduct=c043
usb 3-1: new device strings: Mfr=1, Product=2, SerialNumber=0
usb 3-1: Product: USB-PS/2 Optical Mouse
usb 3-1: Manufacturer: Logitech
usb 3-1: configuration #1 chosen from 1 choice
usbcore: registered new interface driver usblp
PNP: No PS/2 controller found. Probing ports directly.
serio: i8042 KBD port at 0x60,0x64 irq 1
serio: i8042 AUX port at 0x60,0x64 irq 12
mice: PS/2 mouse device common for all mice
i2c /dev entries driver
w83627hf: Found W83627THF chip at 0x290
w83627hf w83627hf.656: Reading VID from GPIO5
input: HID 046a:0021 as /devices/pci0000:00/0000:00:10.0/usb2/2-1/2-1:1.0/input/input3
input: USB HID v1.11 Keyboard [HID 046a:0021] on usb-0000:00:10.0-1
input: HID 046a:0021 as /devices/pci0000:00/0000:00:10.0/usb2/2-1/2-1:1.1/input/input4
input: USB HID v1.11 Device [HID 046a:0021] on usb-0000:00:10.0-1
input: Logitech USB-PS/2 Optical Mouse as /devices/pci0000:00/0000:00:10.1/usb3/3-1/3-1:1.0/input/input5
input: USB HID v1.10 Mouse [Logitech USB-PS/2 Optical Mouse] on usb-0000:00:10.1-1
usbcore: registered new interface driver usbhid
drivers/hid/usbhid/hid-core.c: v2.6:USB HID core driver
Advanced Linux Sound Architecture Driver Version 1.0.14 (Thu May 31 09:03:25 2007 UTC).
ACPI: PCI Interrupt 0000:00:11.5[C] -> GSI 22 (level, low) -> IRQ 22
PCI: Setting latency timer of device 0000:00:11.5 to 64
ALSA device list:
  #0: VIA 8237 with ALC850 at 0xd800, irq 22
TCP cubic registered
NET: Registered protocol family 1
NET: Registered protocol family 17
UDF-fs: No VRS found
XFS mounting filesystem sda1
Ending clean XFS mount for filesystem: sda1
VFS: Mounted root (xfs filesystem) readonly.
Freeing unused kernel memory: 220k freed
XFS mounting filesystem sda4
Ending clean XFS mount for filesystem: sda4
Adding 1959920k swap on /dev/sda2.  Priority:-1 extents:1 across:1959920k
r8169: eth0: link up
agpgart: Found an AGP 3.0 compliant device at 0000:00:00.0.
agpgart: Putting AGP V3 device at 0000:00:00.0 into 8x mode
agpgart: Putting AGP V3 device at 0000:01:00.0 into 8x mode
[drm] Setting GART location based on new memory map
[drm] Loading R200 Microcode
[drm] writeback test succeeded in 1 usecs
Unable to handle kernel NULL pointer dereference at 00000000000002a6 RIP: 
 [<ffffffff802861b6>] vfs_permission+0x6/0x10
PGD 120f9067 PUD 4f5ec067 PMD 0 
Oops: 0000 [1] SMP 
CPU 0 
Pid: 14067, comm: touch Not tainted 2.6.22-rc6-mm1-cfs-v19 #7
RIP: 0010:[<ffffffff802861b6>]  [<ffffffff802861b6>] vfs_permission+0x6/0x10
RSP: 0018:ffff8100083a7e20  EFLAGS: 00010293
RAX: 0000000000000296 RBX: 0000000000000000 RCX: ffff81001cb6ee00
RDX: ffff8100083a7e28 RSI: 0000000000000002 RDI: ffff8100083a7e28
RBP: 00000000fffffff3 R08: 0000000000000002 R09: 00002b70e16872b8
R10: 0000000000000000 R11: 0000000000000246 R12: ffff81001cb6ee00
R13: ffff81006396e828 R14: ffff81000c35da28 R15: 0000000000000002
FS:  00002b70e23fbd10(0000) GS:ffffffff8061b000(0000) knlGS:00000000f6ca96c0
CS:  0010 DS: 0000 ES: 0000 CR0: 000000008005003b
CR2: 00000000000002a6 CR3: 000000001ca29000 CR4: 00000000000006e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400
Process touch (pid: 14067, threadinfo ffff8100083a6000, task ffff81001c589620)
Stack:  ffffffff802a15e0 0000000000000296 ffffffff8021d9c0 00000000000001b6
 ffff81001cb6ee00 ffff81006396e828 0000000000000000 00002b70e1d66850
 0000000000000004 ffff8100083a7f58 ffff81001c589620 0000000000000000
Call Trace:
 [<ffffffff802a15e0>] do_utimes+0x230/0x250
 [<ffffffff8021d9c0>] do_page_fault+0x420/0x8a0
 [<ffffffff8027ca8a>] do_filp_open+0x3a/0x50
 [<ffffffff802a1707>] sys_utimensat+0x37/0xe0
 [<ffffffff8051bb8d>] error_exit+0x0/0x84
 [<ffffffff8020bc5e>] system_call+0x7e/0x83


Code: 48 8b 78 10 e9 d1 fd ff ff 90 53 48 89 fb 48 8d bf b4 00 00 
RIP  [<ffffffff802861b6>] vfs_permission+0x6/0x10
 RSP <ffff8100083a7e20>
CR2: 00000000000002a6
Unable to handle kernel NULL pointer dereference at 00000000000002a6 RIP: 
 [<ffffffff802861b6>] vfs_permission+0x6/0x10
PGD 7942067 PUD 103d6067 PMD 0 
Oops: 0000 [2] SMP 
CPU 0 
Pid: 15996, comm: touch Tainted: G      D 2.6.22-rc6-mm1-cfs-v19 #7
RIP: 0010:[<ffffffff802861b6>]  [<ffffffff802861b6>] vfs_permission+0x6/0x10
RSP: 0018:ffff8100121ffe20  EFLAGS: 00010293
RAX: 0000000000000296 RBX: 0000000000000000 RCX: ffff8100079b1c00
RDX: ffff8100121ffe28 RSI: 0000000000000002 RDI: ffff8100121ffe28
RBP: 00000000fffffff3 R08: 0000000000000002 R09: 00002b1da7ce32b8
R10: 0000000000000000 R11: 0000000000000246 R12: ffff8100079b1c00
R13: ffff81000e1ba0a8 R14: ffff810012a477d0 R15: 0000000000000002
FS:  00002b1da8a57d10(0000) GS:ffffffff8061b000(0000) knlGS:00000000f6ca96c0
CS:  0010 DS: 0000 ES: 0000 CR0: 000000008005003b
CR2: 00000000000002a6 CR3: 000000001c43c000 CR4: 00000000000006e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400
Process touch (pid: 15996, threadinfo ffff8100121fe000, task ffff8100068fac40)
Stack:  ffffffff802a15e0 0000000000000296 ffffffff8021d9c0 00000000000001b6
 ffff8100079b1c00 ffff81000e1ba0a8 0000000000000000 00002b1da83c2850
 0000000000000004 ffff8100121fff58 ffff8100068fac40 0000000000000000
Call Trace:
 [<ffffffff802a15e0>] do_utimes+0x230/0x250
 [<ffffffff8021d9c0>] do_page_fault+0x420/0x8a0
 [<ffffffff8027ca8a>] do_filp_open+0x3a/0x50
 [<ffffffff802a1707>] sys_utimensat+0x37/0xe0
 [<ffffffff8051bb8d>] error_exit+0x0/0x84
 [<ffffffff8020bc5e>] system_call+0x7e/0x83


Code: 48 8b 78 10 e9 d1 fd ff ff 90 53 48 89 fb 48 8d bf b4 00 00 
RIP  [<ffffffff802861b6>] vfs_permission+0x6/0x10
 RSP <ffff8100121ffe20>
CR2: 00000000000002a6
Unable to handle kernel NULL pointer dereference at 00000000000002a6 RIP: 
 [<ffffffff802861b6>] vfs_permission+0x6/0x10
PGD 7b5f067 PUD 1a707067 PMD 0 
Oops: 0000 [3] SMP 
CPU 0 
Pid: 16002, comm: touch Tainted: G      D 2.6.22-rc6-mm1-cfs-v19 #7
RIP: 0010:[<ffffffff802861b6>]  [<ffffffff802861b6>] vfs_permission+0x6/0x10
RSP: 0018:ffff8100588ade20  EFLAGS: 00010293
RAX: 0000000000000296 RBX: 0000000000000000 RCX: ffff810019a51f00
RDX: ffff8100588ade28 RSI: 0000000000000002 RDI: ffff8100588ade28
RBP: 00000000fffffff3 R08: 0000000000000002 R09: 0000000000000002
R10: 0000000000000000 R11: 0000000000000246 R12: ffff810019a51f00
R13: ffff81000e1ba0a8 R14: ffff810012a477d0 R15: 0000000000000002
FS:  00002adda3d7d060(0000) GS:ffffffff8061b000(0000) knlGS:00000000f6ca96c0
CS:  0010 DS: 0000 ES: 0000 CR0: 000000008005003b
CR2: 00000000000002a6 CR3: 0000000004b7b000 CR4: 00000000000006e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400
Process touch (pid: 16002, threadinfo ffff8100588ac000, task ffff81001c58eea0)
Stack:  ffffffff802a15e0 0000000000000296 ffffffff8021d9c0 00000000000001b6
 ffff810019a51f00 ffff81000e1ba0a8 0000000000000000 00002adda38ec850
 0000000000000004 ffff8100588adf58 ffff81001c58eea0 0000000000000000
Call Trace:
 [<ffffffff802a15e0>] do_utimes+0x230/0x250
 [<ffffffff8021d9c0>] do_page_fault+0x420/0x8a0
 [<ffffffff8027ca8a>] do_filp_open+0x3a/0x50
 [<ffffffff802a1707>] sys_utimensat+0x37/0xe0
 [<ffffffff8051bb8d>] error_exit+0x0/0x84
 [<ffffffff8020bc5e>] system_call+0x7e/0x83


Code: 48 8b 78 10 e9 d1 fd ff ff 90 53 48 89 fb 48 8d bf b4 00 00 
RIP  [<ffffffff802861b6>] vfs_permission+0x6/0x10
 RSP <ffff8100588ade20>
CR2: 00000000000002a6
-- 
Markus

Re: 2.6.22-rc6-mm1-cfs-v19 Unable to handle kernel NULL pointer dereference (reproducable)

[Andrew Morton]

On Sun, 8 Jul 2007 07:14:52 +0200 Markus Trippelsdorf <markus@trippelsdorf.de> wrote:

> Just got this oops while I was updating my system:
> 
> Unable to handle kernel NULL pointer dereference at 00000000000002a6 RIP:
>  [<ffffffff802861b6>] vfs_permission+0x6/0x10
> PGD 120f9067 PUD 4f5ec067 PMD 0
> Oops: 0000 [1] SMP
> CPU 0
> Pid: 14067, comm: touch Not tainted 2.6.22-rc6-mm1-cfs-v19 #7
> RIP: 0010:[<ffffffff802861b6>]  [<ffffffff802861b6>] vfs_permission+0x6/0x10
> RSP: 0018:ffff8100083a7e20  EFLAGS: 00010293
> RAX: 0000000000000296 RBX: 0000000000000000 RCX: ffff81001cb6ee00
> RDX: ffff8100083a7e28 RSI: 0000000000000002 RDI: ffff8100083a7e28
> RBP: 00000000fffffff3 R08: 0000000000000002 R09: 00002b70e16872b8
> R10: 0000000000000000 R11: 0000000000000246 R12: ffff81001cb6ee00
> R13: ffff81006396e828 R14: ffff81000c35da28 R15: 0000000000000002
> FS:  00002b70e23fbd10(0000) GS:ffffffff8061b000(0000) knlGS:00000000f6ca96c0
> CS:  0010 DS: 0000 ES: 0000 CR0: 000000008005003b
> CR2: 00000000000002a6 CR3: 000000001ca29000 CR4: 00000000000006e0
> DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
> DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400
> Process touch (pid: 14067, threadinfo ffff8100083a6000, task ffff81001c589620)
> Stack:  ffffffff802a15e0 0000000000000296 ffffffff8021d9c0 00000000000001b6
>  ffff81001cb6ee00 ffff81006396e828 0000000000000000 00002b70e1d66850
>  0000000000000004 ffff8100083a7f58 ffff81001c589620 0000000000000000
> Call Trace:
>  [<ffffffff802a15e0>] do_utimes+0x230/0x250
>  [<ffffffff8021d9c0>] do_page_fault+0x420/0x8a0
>  [<ffffffff8027ca8a>] do_filp_open+0x3a/0x50
>  [<ffffffff802a1707>] sys_utimensat+0x37/0xe0
>  [<ffffffff8051bb8d>] error_exit+0x0/0x84
>  [<ffffffff8020bc5e>] system_call+0x7e/0x83
> 
> 
> Code: 48 8b 78 10 e9 d1 fd ff ff 90 53 48 89 fb 48 8d bf b4 00 00
> RIP  [<ffffffff802861b6>] vfs_permission+0x6/0x10
>  RSP <ffff8100083a7e20>
> CR2: 00000000000002a6
> 
> I was running the »paludis« package manager: 
> 
> make[1]: Leaving directory `/var/tmp/paludis/sys-libs/gpm-1.20.1-r6/work/gpm-1.20.1/contrib'
> >>> Done src_compile
> >>> Skipping src_test (SKIP_FUNCTIONS)
> >>> Starting builtin_saveenv
> >>> Done builtin_saveenv
> >>> Completed ebuild phases loadenv unpack compile test saveenv
> >>> Running ebuild phases loadenv install saveenv as root:root...
> >>> Starting builtin_loadenv
> >>> Done builtin_loadenv
> >>> Starting src_install
> touch src/.depend # to prevent unecessary warnings
> make: *** [dep] Killed

ug.  nd.dentry.d_inode (as set up by do_utimes()) is garbage.  I don't know
what could have caused that.


> Running "touch  /var/tmp/paludis/sys-libs/gpm-1.20.1-r6/work/gpm-1.20.1/src/.depend" 
> triggers this oops.

What type of filesystem is at /var/tmp?

Is it repeatable after a reboot?

Re: 2.6.22-rc6-mm1-cfs-v19 Unable to handle kernel NULL pointer dereference (reproducable)

[Markus Trippelsdorf]

On Sun, Jul 08, 2007 at 01:20:16AM -0700, Andrew Morton wrote:
> On Sun, 8 Jul 2007 07:14:52 +0200 Markus Trippelsdorf <markus@trippelsdorf.de> wrote:
> 
> ...
> > touch src/.depend # to prevent unecessary warnings
> > make: *** [dep] Killed
> 
> ug.  nd.dentry.d_inode (as set up by do_utimes()) is garbage.  I don't know
> what could have caused that.
> 
> 
> > Running "touch  /var/tmp/paludis/sys-libs/gpm-1.20.1-r6/work/gpm-1.20.1/src/.depend" 
> > triggers this oops.
> 
> What type of filesystem is at /var/tmp?
> 
> Is it repeatable after a reboot?
> 

The filesystem at /var/tmp was xfs. And yes it was repeatable after a
reboot...

So I ran xfs_check on that partition and it reported errors. Then I ran
xfs_repair and after that rebooted, but the problem was still there.
Finally I switched the partition back to ext3, because it got too scary.
But the oops is now repeatable even on this new ext3 partition.

There are no errors in the smartd log. I will run "smartctl -t long" now
and will report back if it finds any errors.

-- 
Markus

Re: 2.6.22-rc6(mm1) Unable to handle kernel NULL pointer dereference - git-bisect result

[Markus Trippelsdorf]

On Sun, Jul 08, 2007 at 12:09:11PM +0200, Markus Trippelsdorf wrote:
> On Sun, Jul 08, 2007 at 01:20:16AM -0700, Andrew Morton wrote:
> > On Sun, 8 Jul 2007 07:14:52 +0200 Markus Trippelsdorf <markus@trippelsdorf.de> wrote:
> > 
> > ...
> > > touch src/.depend # to prevent unecessary warnings
> > > make: *** [dep] Killed
> > 
> > ug.  nd.dentry.d_inode (as set up by do_utimes()) is garbage.  I don't know
> > what could have caused that.
> > 
> > 
> > > Running "touch  /var/tmp/paludis/sys-libs/gpm-1.20.1-r6/work/gpm-1.20.1/src/.depend" 
> > > triggers this oops.
> > 
> > What type of filesystem is at /var/tmp?
> > 
> > Is it repeatable after a reboot?
> > 
> 
> The filesystem at /var/tmp was xfs. And yes it was repeatable after a
> reboot...
> 
> So I ran xfs_check on that partition and it reported errors. Then I ran
> xfs_repair and after that rebooted, but the problem was still there.
> Finally I switched the partition back to ext3, because it got too scary.
> But the oops is now repeatable even on this new ext3 partition.

I tested this further and it turned out that the Linus tree is also
affected. So I ran git-bisect, after I found out that version
2.6.21.6 was not affected by this bug.

This is the result:

gentoox2 linux # git bisect bad
1c710c896eb461895d3c399e15bb5f20b39c9073 is first bad commit
commit 1c710c896eb461895d3c399e15bb5f20b39c9073
Author: Ulrich Drepper <drepper@redhat.com>
Date:   Tue May 8 00:33:25 2007 -0700

    utimensat implementation

    Implement utimensat(2) which is an extension to futimesat(2) in that it

    a) supports nano-second resolution for the timestamps
    b) allows to selectively ignore the atime/mtime value
    c) allows to selectively use the current time for either atime or mtime
    d) supports changing the atime/mtime of a symlink itself along the lines
       of the BSD lutimes(3) functions

    For this change the internally used do_utimes() functions was changed to
    accept a timespec time value and an additional flags parameter.

    Additionally the sys_utime function was changed to match compat_sys_utime
    which already use do_utimes instead of duplicating the work.

    Also, the completely missing futimensat() functionality is added.  We have
    such a function in glibc but we have to resort to using /proc/self/fd/* which
    not everybody likes (chroot etc).

    Test application (the syscall number will need per-arch editing):
...

    [akpm@linux-foundation.org: add missing i386 syscall table entry]
    Signed-off-by: Ulrich Drepper <drepper@redhat.com>
    Cc: Alexey Dobriyan <adobriyan@openvz.org>
    Cc: Michael Kerrisk <mtk-manpages@gmx.net>
    Cc: <linux-arch@vger.kernel.org>
    Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
    Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

HTH,
-- 
Markus

Re: 2.6.22-rc6(mm1) Unable to handle kernel NULL pointer dereference - git-bisect result

[Linus Torvalds]

On Sun, 8 Jul 2007, Markus Trippelsdorf wrote:
> 
> I tested this further and it turned out that the Linus tree is also
> affected. So I ran git-bisect, after I found out that version
> 2.6.21.6 was not affected by this bug.

git-bisect is wonderful.

> gentoox2 linux # git bisect bad
> 1c710c896eb461895d3c399e15bb5f20b39c9073 is first bad commit
> commit 1c710c896eb461895d3c399e15bb5f20b39c9073
> Author: Ulrich Drepper <drepper@redhat.com>

Ok, I see what's wrong.

We're doing "vfs_permission()" and passing in "nd" to it when "times" is 
NULL, but Uli didn't even *initialize* it for the case of

	filename == NULL && dfd != AT_FDCWD

so yeah, it's broken.

I was planning on doing 2.6.22 today, so I'm actually inclined to revert 
the commit entirely, even though it looks like it's probably fairly 
trivial to fix.

But if we get a really quick and obvious fix, I guess I'll apply it. I 
have to say, the new do_utimes() code is pretty ugly compared to the old 
one exactly in the added special cases (the ones that caused this bug..)

Uli?

		Linus

Re: 2.6.22-rc6(mm1) Unable to handle kernel NULL pointer dereference - git-bisect result

[Ulrich Drepper]

-----BEGIN PGP SIGNED MESSAGE-----
Hash: SHA1

Markus Trippelsdorf wrote:
> I tested this further and it turned out that the Linus tree is also
> affected. So I ran git-bisect, after I found out that version
> 2.6.21.6 was not affected by this bug.

Try this patch.  The vfs_permission test can be skipped since the VFS
isn't involved.  We got the inode etc from a file descriptor.


Signed-Off-By: Ulrich Drepper <drepper@redhat.com>

diff --git a/fs/utimes.c b/fs/utimes.c
index 480f7c8..873edcb 100644
- --- a/fs/utimes.c
+++ b/fs/utimes.c
@@ -106,7 +106,8 @@ long do_utimes(int dfd, char __user *filename, struct timespec *times, int flags
                 if (IS_IMMUTABLE(inode))
                         goto dput_and_out;

- -               if (current->fsuid != inode->i_uid &&
+               if (f == NULL &&
+                   current->fsuid != inode->i_uid &&
                    (error = vfs_permission(&nd, MAY_WRITE)) != 0)
                        goto dput_and_out;
        }


- --
➧ Ulrich Drepper ➧ Red Hat, Inc. ➧ 444 Castro St ➧ Mountain View, CA ❖
-----BEGIN PGP SIGNATURE-----
Version: GnuPG v1.4.7 (GNU/Linux)

iD8DBQFGkRmj2ijCOnn/RHQRAkuyAJ41CIDhT8yKb6SKX14ylFXznO6gfwCfdtEo
4Gt9hPsotmKddwE2xdYkJmQ=
=JyVn
-----END PGP SIGNATURE-----

Re: 2.6.22-rc6(mm1) Unable to handle kernel NULL pointer dereference - git-bisect result

[Markus Trippelsdorf]

On Sun, Jul 08, 2007 at 10:06:43AM -0700, Ulrich Drepper wrote:
> -----BEGIN PGP SIGNED MESSAGE-----
> Hash: SHA1
> 
> Markus Trippelsdorf wrote:
> > I tested this further and it turned out that the Linus tree is also
> > affected. So I ran git-bisect, after I found out that version
> > 2.6.21.6 was not affected by this bug.
> 
> Try this patch.  The vfs_permission test can be skipped since the VFS
> isn't involved.  We got the inode etc from a file descriptor.
> 
> 
> Signed-Off-By: Ulrich Drepper <drepper@redhat.com>
> 
> diff --git a/fs/utimes.c b/fs/utimes.c
> index 480f7c8..873edcb 100644
> - --- a/fs/utimes.c
> +++ b/fs/utimes.c
> @@ -106,7 +106,8 @@ long do_utimes(int dfd, char __user *filename, struct timespec *times, int flags
>                  if (IS_IMMUTABLE(inode))
>                          goto dput_and_out;
> 
> - -               if (current->fsuid != inode->i_uid &&
> +               if (f == NULL &&
> +                   current->fsuid != inode->i_uid &&
>                     (error = vfs_permission(&nd, MAY_WRITE)) != 0)
>                         goto dput_and_out;
>         }
> 
> 

I had to hand apply the patch, but it solved the problem.
Thanks.
-- 
Markus

Re: 2.6.22-rc6(mm1) Unable to handle kernel NULL pointer dereference - git-bisect result

[Al Viro]

On Sun, Jul 08, 2007 at 10:06:43AM -0700, Ulrich Drepper wrote:
> -----BEGIN PGP SIGNED MESSAGE-----
> Hash: SHA1
> 
> Markus Trippelsdorf wrote:
> > I tested this further and it turned out that the Linus tree is also
> > affected. So I ran git-bisect, after I found out that version
> > 2.6.21.6 was not affected by this bug.
> 
> Try this patch.  The vfs_permission test can be skipped since the VFS
> isn't involved.  We got the inode etc from a file descriptor.
 
Like hell.  At the very least you want it to be opened for write.
And even that is dubious, since "process has write access to file"
is not quite the same thing as "somebody had given the process a
descriptor opened for write".

Re: 2.6.22-rc6(mm1) Unable to handle kernel NULL pointer dereference - git-bisect result

[Ulrich Drepper]

-----BEGIN PGP SIGNED MESSAGE-----
Hash: SHA1

Al Viro wrote:
> Like hell.  At the very least you want it to be opened for write.
> And even that is dubious, since "process has write access to file"
> is not quite the same thing as "somebody had given the process a
> descriptor opened for write".

But the real permissions tests are performed in notify_change.  I think
all this is consistent with how, for instance, fchmod works.  The
additional tests in fchmod which aren't here (IS_RDONLY and IS_APPEND)
would also apply to the case where a file name is given.  So, either the
code was inconsistent already are these tests are really not needed.

- --
➧ Ulrich Drepper ➧ Red Hat, Inc. ➧ 444 Castro St ➧ Mountain View, CA ❖
-----BEGIN PGP SIGNATURE-----
Version: GnuPG v1.4.7 (GNU/Linux)

iD8DBQFGkSHa2ijCOnn/RHQRAp0RAJ9ouvOd52feTPuFurxj8LzHZuGZsACgwxA8
ybEo1xmvakkKVenWc07PYhs=
=5DBy
-----END PGP SIGNATURE-----

Re: 2.6.22-rc6(mm1) Unable to handle kernel NULL pointer dereference - git-bisect result

[Linus Torvalds]

On Sun, 8 Jul 2007, Ulrich Drepper wrote:
> 
> But the real permissions tests are performed in notify_change.  I think
> all this is consistent with how, for instance, fchmod works.  The
> additional tests in fchmod which aren't here (IS_RDONLY and IS_APPEND)
> would also apply to the case where a file name is given.  So, either the
> code was inconsistent already are these tests are really not needed.

No.

notify_change() does *not* do permission checks for 
ATTR_CTIME/MTIME/ATIME.

It does them for the "xxx_SET" attributes, but MTIME/ATIME is expected to 
change when other things change, so notify_change() expects that those 
_other_ changes have been validated from a security standpoint!

utimes() is special.

		Linus

Re: 2.6.22-rc6(mm1) Unable to handle kernel NULL pointer dereference - git-bisect result

[Ulrich Drepper]

-----BEGIN PGP SIGNED MESSAGE-----
Hash: SHA1

Linus Torvalds wrote:
> notify_change() does *not* do permission checks for 
> ATTR_CTIME/MTIME/ATIME.

Then I don't understand

        /* Check for setting the inode time. */
        if (ia_valid & (ATTR_MTIME_SET | ATTR_ATIME_SET)) {
                if (current->fsuid != inode->i_uid && !capable(CAP_FOWNER))
                        goto error;
        }

in inode_change_ok.  This seems to me exactly like the check needed.

- --
➧ Ulrich Drepper ➧ Red Hat, Inc. ➧ 444 Castro St ➧ Mountain View, CA ❖
-----BEGIN PGP SIGNATURE-----
Version: GnuPG v1.4.7 (GNU/Linux)

iD8DBQFGkSv12ijCOnn/RHQRAkp8AJ9q9vuy1ACjiYHteRac4Q86WO5wlgCfbr11
I0d6V5VGJGmpkuc9NsO6lkE=
=imhB
-----END PGP SIGNATURE-----

Re: 2.6.22-rc6(mm1) Unable to handle kernel NULL pointer dereference - git-bisect result

[Al Viro]

On Sun, Jul 08, 2007 at 11:24:53AM -0700, Ulrich Drepper wrote:
> -----BEGIN PGP SIGNED MESSAGE-----
> Hash: SHA1
> 
> Linus Torvalds wrote:
> > notify_change() does *not* do permission checks for 
> > ATTR_CTIME/MTIME/ATIME.
> 
> Then I don't understand
> 
>         /* Check for setting the inode time. */
>         if (ia_valid & (ATTR_MTIME_SET | ATTR_ATIME_SET)) {
>                 if (current->fsuid != inode->i_uid && !capable(CAP_FOWNER))
>                         goto error;
>         }
> 
> in inode_change_ok.  This seems to me exactly like the check needed.

Sigh...  There are two operations.
	1) set the timestamp to user-supplied value.  Owner-only.
	2) have the timestamp set to _now_.  Obviously can be done not
only by the owner (think of e.g. write(2)); having write access is
sufficient.

ATTR_MTIME_SET is the former.  ATTR_MTIME without ATTR_MTIME_SET is the
latter and that's what utimes(foo, NULL) ends up doing.

Re: 2.6.22-rc6(mm1) Unable to handle kernel NULL pointer dereference - git-bisect result

[Linus Torvalds]

On Sun, 8 Jul 2007, Ulrich Drepper wrote:

> -----BEGIN PGP SIGNED MESSAGE-----
> Hash: SHA1
> 
> Linus Torvalds wrote:
> > notify_change() does *not* do permission checks for 
> > ATTR_CTIME/MTIME/ATIME.
> 
> Then I don't understand
> 
>         /* Check for setting the inode time. */
>         if (ia_valid & (ATTR_MTIME_SET | ATTR_ATIME_SET)) {
>                 if (current->fsuid != inode->i_uid && !capable(CAP_FOWNER))
>                         goto error;
>         }
> 
> in inode_change_ok.  This seems to me exactly like the check needed.

No it's not. It really allows only the _owner_ to change MTIME/ATIME.

And the thing is, other people _can_ change MTIME/ATIME, but only to the 
current time!

This is why ATTR_MTIME_SET ("set it to a _specific_ time") is so different 
from ATTR_MTIME ("set it to the _current_ time").

The former is for times() with times != NULL, and is strictly limited to 
only the owner (or root).

The latter is a "anybody who can change the inode can implicitly also 
change the inode timestamps, but only to the _current_ time".

In other words, the ATTR_A/MTIME_SET thing allows people to _lie_ about 
the time, and only the owner is allowed to do that. Which is why they are 
very different.

		Linus

Re: 2.6.22-rc6(mm1) Unable to handle kernel NULL pointer dereference - git-bisect result

[Linus Torvalds]

On Sun, 8 Jul 2007, Linus Torvalds wrote:
> 
> No.
> 
> notify_change() does *not* do permission checks for 
> ATTR_CTIME/MTIME/ATIME.
> 
> It does them for the "xxx_SET" attributes, but MTIME/ATIME is expected to 
> change when other things change, so notify_change() expects that those 
> _other_ changes have been validated from a security standpoint!
> 
> utimes() is special.

This might be an acceptable patch.

Al? What do you think? Basically, it says that

 - the file owner can always set MTIME/ATIME, of course

 - non-owners can set it only when they have write permissions, and if it 
   was a file descriptor, the only way for us to know that they have write 
   permissions is if it's opened writably, which is hopefully equivalent 
   to that MAY_WRITE test (except the MAY_WRITE test was done at _open_ 
   time).

This would seem to be the minimal change, and I think it's right.

		Linus

---
 fs/utimes.c |   13 ++++++++++---
 1 files changed, 10 insertions(+), 3 deletions(-)

diff --git a/fs/utimes.c b/fs/utimes.c
index 480f7c8..b3c8895 100644
--- a/fs/utimes.c
+++ b/fs/utimes.c
@@ -106,9 +106,16 @@ long do_utimes(int dfd, char __user *filename, struct timespec *times, int flags
                 if (IS_IMMUTABLE(inode))
                         goto dput_and_out;
 
-		if (current->fsuid != inode->i_uid &&
-		    (error = vfs_permission(&nd, MAY_WRITE)) != 0)
-			goto dput_and_out;
+		if (current->fsuid != inode->i_uid) {
+			if (f) {
+				if (!(f->f_mode & FMODE_WRITE))
+					goto dput_and_out;
+			} else {
+				error = vfs_permission(&nd, MAY_WRITE);
+				if (error)
+					goto dput_and_out;
+			}
+		}
 	}
 	mutex_lock(&inode->i_mutex);
 	error = notify_change(dentry, &newattrs);

Re: 2.6.22-rc6(mm1) Unable to handle kernel NULL pointer dereference - git-bisect result

[Al Viro]

On Sun, Jul 08, 2007 at 11:30:15AM -0700, Linus Torvalds wrote:
>  - non-owners can set it only when they have write permissions, and if it 
>    was a file descriptor, the only way for us to know that they have write 
>    permissions is if it's opened writably, which is hopefully equivalent 
>    to that MAY_WRITE test (except the MAY_WRITE test was done at _open_ 
>    time).
> 
> This would seem to be the minimal change, and I think it's right.

Yeah, FMODE_WRITE is probably right.

Re: 2.6.22-rc6(mm1) Unable to handle kernel NULL pointer dereference - git-bisect result

[Linus Torvalds]

On Sun, 8 Jul 2007, Linus Torvalds wrote:
> 
> This would seem to be the minimal change, and I think it's right.

Side note: I considered just changing do_utimes() to use 
ATIME_SET/MTIME_SET instead, which would simplify the logic a lot..

But it turns out that the semantics for A/MTIME_SET is that only the owner 
of the file can do that. So the "!times" case is simply _fundamentally_ 
different from a permissions check standpoint, and there we have to check 
for "writable" rather than anything else (although ownership will override 
it).

So rather than simplify the thing, I had to add code. Oh, well.

I do think that it would be even nicer to just have a function that fills 
in the "struct nameidata" from the dfd. I think we should be able to: the 
"struct file" really does have the "f_path" thing with both dentry and mnt 
information, and that would clean up that whole ugly "filepointer-vs-nd" 
thing a lot.

That would be an "Al cleanup", though. What do you think, Al?

			Linus

Re: 2.6.22-rc6(mm1) Unable to handle kernel NULL pointer dereference - git-bisect result

[Al Viro]

On Sun, Jul 08, 2007 at 11:38:20AM -0700, Linus Torvalds wrote:
> I do think that it would be even nicer to just have a function that fills 
> in the "struct nameidata" from the dfd. I think we should be able to: the 
> "struct file" really does have the "f_path" thing with both dentry and mnt 
> information, and that would clean up that whole ugly "filepointer-vs-nd" 
> thing a lot.
> 
> That would be an "Al cleanup", though. What do you think, Al?

I think that we need to go the other way round - gather nameidata
->nd and ->dentry into struct path and pass pointer to that instead...

But that's .23-rc1 fodder, if not .23-rc2 one (we might want to
do -rc2 with just that, to avoid conflicts with pending patches).
Definitely not for .22-final.

Re: 2.6.22-rc6(mm1) Unable to handle kernel NULL pointer dereference - git-bisect result

[Linus Torvalds]

On Sun, 8 Jul 2007, Al Viro wrote:
>
> I think that we need to go the other way round - gather nameidata
> ->nd and ->dentry into struct path and pass pointer to that instead...

Yeah, that sounds fine too.

> But that's .23-rc1 fodder, if not .23-rc2 one (we might want to
> do -rc2 with just that, to avoid conflicts with pending patches).
> Definitely not for .22-final.

Oh, absolutely. I wasn't implying that we would want to do it today, but 
as it is now, just looking at that code makes my eyes water.. So it would 
be nice to fix that up.

One reason I would almost prefer an "nd", though, is that it would allow 
us to in general always just convert anythign that now looks up a path to 
look up "a path or file descriptor" instead. Those things need "nd" right 
now, and if it's a "struct path", then you'll always have the two 
different cases, rather than just the common "release_nd()" at the end.

		Linus

Re: 2.6.22-rc6(mm1) Unable to handle kernel NULL pointer dereference - git-bisect result

[Al Viro]

On Sun, Jul 08, 2007 at 12:00:55PM -0700, Linus Torvalds wrote:
> 
> 
> On Sun, 8 Jul 2007, Al Viro wrote:
> >
> > I think that we need to go the other way round - gather nameidata
> > ->nd and ->dentry into struct path and pass pointer to that instead...
> 
> Yeah, that sounds fine too.
> 
> > But that's .23-rc1 fodder, if not .23-rc2 one (we might want to
> > do -rc2 with just that, to avoid conflicts with pending patches).
> > Definitely not for .22-final.
> 
> Oh, absolutely. I wasn't implying that we would want to do it today, but 
> as it is now, just looking at that code makes my eyes water.. So it would 
> be nice to fix that up.
> 
> One reason I would almost prefer an "nd", though, is that it would allow 
> us to in general always just convert anythign that now looks up a path to 
> look up "a path or file descriptor" instead. Those things need "nd" right 
> now, and if it's a "struct path", then you'll always have the two 
> different cases, rather than just the common "release_nd()" at the end.

Umm...  Perhaps, but I'm not sure if we want to play with refcounts for
mnt/dentry in file case.  If we do, we can always do your helper, but
have it fill supplied struct file - either from fd or from nameidata.
And release_nd() before returning from helper.

Re: 2.6.22-rc6(mm1) Unable to handle kernel NULL pointer dereference - git-bisect result

[Al Viro]

On Sun, Jul 08, 2007 at 10:41:46AM -0700, Ulrich Drepper wrote:
> -----BEGIN PGP SIGNED MESSAGE-----
> Hash: SHA1
> 
> Al Viro wrote:
> > Like hell.  At the very least you want it to be opened for write.
> > And even that is dubious, since "process has write access to file"
> > is not quite the same thing as "somebody had given the process a
> > descriptor opened for write".
> 
> But the real permissions tests are performed in notify_change.  I think
> all this is consistent with how, for instance, fchmod works.  The
> additional tests in fchmod which aren't here (IS_RDONLY and IS_APPEND)
> would also apply to the case where a file name is given.  So, either the
> code was inconsistent already are these tests are really not needed.

Yes, it's either that, or you haven't bothered to read what it really
does.  ATTR_UID et.al. are checked in inode_change_ok().  So is
ATTR_MTIME_SET (only owner can explicitly set timestamps).  ATTR_MTIME
is not and *should* *not* be checked there.  Exactly because it's
done as a side effect of many operations with access control of their
own and nothing that could be pushed down into notify_change() path.
Think of e.g. write(2) - by the time you get to notify_change(), you
don't even have a file descriptor.  Just the dentry and process writing
to file doesn't have to have *any* permissions on it.

Hell, _try_ it.  Build the kernel with your patch and without it.
Call utimes() with NULL second argument on a file you have no write
access to.  See if the timestamps change.

Re: 2.6.22-rc6-mm1-cfs-v19 Unable to handle kernel NULL pointer dereference (reproducable)

[Lenar Lõhmus]

Markus Trippelsdorf wrote:
> Just got this oops while I was updating my system:
>
> Unable to handle kernel NULL pointer dereference at 00000000000002a6 RIP:
>  [<ffffffff802861b6>] vfs_permission+0x6/0x10
>   
The same thing just happened here during dist-upgrade with
stock ubuntu 2.6.22-7-generic x86_64 kernel (based on -rc4 I think):

[ 6361.299928] Unable to handle kernel NULL pointer dereference at 
00000000000002a2 RIP:
[ 6361.299933]  [<ffffffff802a3526>] vfs_permission+0x6/0x10

ext3 in use.

L.