3.0.65-stable review

This is the start of the stable review cycle for the 3.0.65 release. There are 4 patches in this series, all will be posted as a response to this one. If anyone has any issues with these being applied, please let me know.

Responses should be made by Sun Feb 17 22:53:56 UTC 2013. Anything received after that time might be too late.

The whole patch series can be found in one patch at:

	kernel.org/pub/linux/kernel/v3.0/stable-review/patch-3.0.65-rc1.gz

and the diffstat can be found below.

thanks,

greg k-h

-------------
Pseudo-Shortlog of commits:

Greg Kroah-Hartman <[email protected]>

    Linux 3.0.65-rc1

Alexander Duyck <[email protected]>
igb: Remove artificial restriction on RQDPC stat reading

Rafael J. Wysocki <[email protected]>
PCI/PM: Clean up PME state when removing a device

Jan Beulich <[email protected]>
x86/xen: don't assume %ds is usable in xen_iret for 32-bit PVOPS.

Mel Gorman <[email protected]>
x86/mm: Check if PUD is large when validating a kernel address

-------------

Diffstat:

 Makefile                       |  4 ++--
 arch/x86/include/asm/pgtable.h |  5 +++++
 arch/x86/mm/init_64.c          |  3 +++
 arch/x86/xen/xen-asm_32.S      | 14 +++++++-------
 drivers/net/igb/igb_main.c     |  8 +++++---
 drivers/pci/remove.c           |  2 ++
 6 files changed, 24 insertions(+), 12 deletions(-)

3.0-stable review patch. If anyone has any objections, please let me know.

------------------

From: Mel Gorman <[email protected]>

commit 0ee364eb316348ddf3e0dfcd986f5f13f528f821 upstream.

A user reported the following oops when a backup process reads /proc/kcore:

 BUG: unable to handle kernel paging request at ffffbb00ff33b000
 IP: [<ffffffff8103157e>] kern_addr_valid+0xbe/0x110
 [...]

 Call Trace:
  [<ffffffff811b8aaa>] read_kcore+0x17a/0x370
  [<ffffffff811ad847>] proc_reg_read+0x77/0xc0
  [<ffffffff81151687>] vfs_read+0xc7/0x130
  [<ffffffff811517f3>] sys_read+0x53/0xa0
  [<ffffffff81449692>] system_call_fastpath+0x16/0x1b

Investigation determined that the bug triggered when reading system RAM at the 4G mark. On this system, that was the first address using 1G pages for the virt->phys direct mapping so the PUD is pointing to a physical address, not a PMD page.

The problem is that the page table walker in kern_addr_valid() is not checking pud_large() and treats the physical address as if it was a PMD. If it happens to look like pmd_none then it'll silently fail, probably returning zeros instead of real data. If the data happens to look like a present PMD though, it will be walked resulting in the oops above.

This patch adds the necessary pud_large() check.

Unfortunately the problem was not readily reproducible and now they are running the backup program without accessing /proc/kcore so the patch has not been validated but I think it makes sense.

---
 arch/x86/include/asm/pgtable.h |    5 +++++
 arch/x86/mm/init_64.c          |    3 +++
 2 files changed, 8 insertions(+)

@@ -142,6 +142,11 @@ static inline unsigned long pmd_pfn(pmd_
 	return (pmd_val(pmd) & PTE_PFN_MASK) >> PAGE_SHIFT;
 }
 
+static inline unsigned long pud_pfn(pud_t pud)
+{
+	return (pud_val(pud) & PTE_PFN_MASK) >> PAGE_SHIFT;
+}
+
 #define pte_page(pte)	pfn_to_page(pte_pfn(pte))
 
 static inline int pmd_large(pmd_t pte)

@@ -831,6 +831,9 @@ int kern_addr_valid(unsigned long addr)
 	if (pud_none(*pud))
 		return 0;
 
+	if (pud_large(*pud))
+		return pfn_valid(pud_pfn(*pud));
+
 	pmd = pmd_offset(pud, addr);
 	if (pmd_none(*pmd))
 		return 0;

3.0-stable review patch. If anyone has any objections, please let me know.

------------------

From: Jan Beulich <[email protected]>

commit 13d2b4d11d69a92574a55bfd985cfb0ca77aebdc upstream.

This fixes CVE-2013-0228 / XSA-42

Drew Jones while working on CVE-2013-0190 found that that unprivileged guest user in 32bit PV guest can use to crash the > guest with the panic like this:

-------------

general protection fault: 0000 [#1] SMP
last sysfs file: /sys/devices/vbd-51712/block/xvda/dev
Modules linked in: sunrpc ipt_REJECT nf_conntrack_ipv4 nf_defrag_ipv4

iptable_filter ip_tables ip6t_REJECT nf_conntrack_ipv6 nf_defrag_ipv6 xt_state nf_conntrack ip6table_filter ip6_tables ipv6 xen_netfront ext4 mbcache jbd2 xen_blkfront dm_mirror dm_region_hash dm_log dm_mod [last
unloaded: scsi_wait_scan]

Pid: 1250, comm: r Not tainted 2.6.32-356.el6.i686 #1
EIP: 0061:[<c0407462>] EFLAGS: 00010086 CPU: 0
EIP is at xen_iret+0x12/0x2b
EAX: eb8d0000 EBX: 00000001 ECX: 08049860 EDX: 00000010
ESI: 00000000 EDI: 003d0f00 EBP: b77f8388 ESP: eb8d1fe0
DS: 0000 ES: 007b FS: 0000 GS: 00e0 SS: 0069
Process r (pid: 1250, ti=eb8d0000 task=c2953550 task.ti=eb8d0000)

Stack:
 00000000 0027f416 00000073 00000206 b77f8364 0000007b 00000000 00000000
Call Trace:
Code: c3 8b 44 24 18 81 4c 24 38 00 02 00 00 8d 64 24 30 e9 03 00 00 00
8d 76 00 f7 44 24 08 00 00 02 80 75 33 50 b8 00 e0 ff ff 21 e0 <8b> 40
10 8b 04 85 a0 f6 ab c0 8b 80 0c b0 b3 c0 f6 44 24 0d 02
EIP: [<c0407462>] xen_iret+0x12/0x2b SS:ESP 0069:eb8d1fe0
general protection fault: 0000 [#2]
---[ end trace ab0d29a492dcd330 ]---
Kernel panic - not syncing: Fatal exception
Pid: 1250, comm: r Tainted: G      D    ---------------
2.6.32-356.el6.i686 #1
Call Trace:
 [<c08476df>] ? panic+0x6e/0x122
 [<c084b63c>] ? oops_end+0xbc/0xd0
 [<c084b260>] ? do_general_protection+0x0/0x210
 [<c084a9b7>] ? error_code+0x73/
-------------

Petr says: "
I've analysed the bug and I think that xen_iret() cannot cope with mangled DS, in this case zeroed out (null selector/descriptor) by either xen_failsafe_callback() or RESTORE_REGS because the corresponding LDT entry was invalidated by the reproducer. "

Jan took a look at the preliminary patch and came up a fix that solves this problem:

"This code gets called after all registers other than those handled by IRET got already restored, hence a null selector in %ds or a non-null one that got loaded from a code or read-only data descriptor would cause a kernel mode fault (with the potential of crashing the kernel as a whole, if panic_on_oops is set)."

The way to fix this is to realize that the we can only relay on the registers that IRET restores. The two that are guaranteed are the %cs and %ss as they are always fixed GDT selectors. Also they are inaccessible from user mode - so they cannot be altered. This is the approach taken in this patch.

Another alternative option suggested by Jan would be to relay on the subtle realization that using the %ebp or %esp relative references uses the %ss segment. In which case we could switch from using %eax to %ebp and would not need the %ss over-rides. That would also require one extra instruction to compensate for the one place where the register is used as scaled index. However Andrew pointed out that is too subtle and if further work was to be done in this code-path it could escape folks attention and lead to accidents.

---
 arch/x86/xen/xen-asm_32.S |   14 +++++++-------
 1 file changed, 7 insertions(+), 7 deletions(-)

@@ -88,11 +88,11 @@ ENTRY(xen_iret)
 	 */
 #ifdef CONFIG_SMP
 	GET_THREAD_INFO(%eax)
-	movl TI_cpu(%eax), %eax
-	movl __per_cpu_offset(,%eax,4), %eax
-	mov xen_vcpu(%eax), %eax
+	movl %ss:TI_cpu(%eax), %eax
+	movl %ss:__per_cpu_offset(,%eax,4), %eax
+	mov %ss:xen_vcpu(%eax), %eax
 #else
-	movl xen_vcpu, %eax
+	movl %ss:xen_vcpu, %eax
 #endif
 
 	/* check IF state we're restoring */

@@ -105,11 +105,11 @@ ENTRY(xen_iret)
 	 * resuming the code, so we don't have to be worried about
 	 * being preempted to another CPU.
 	 */
-	setz XEN_vcpu_info_mask(%eax)
+	setz %ss:XEN_vcpu_info_mask(%eax)
 xen_iret_start_crit:
 
 	/* check for unmasked and pending */
-	cmpw $0x0001, XEN_vcpu_info_pending(%eax)
+	cmpw $0x0001, %ss:XEN_vcpu_info_pending(%eax)
 
 	/*
 	 * If there's something pending, mask events again so we can

@@ -117,7 +117,7 @@ xen_iret_start_crit:
 	 * touch XEN_vcpu_info_mask.
 	 */
 	jne 1f
-	movb $1, XEN_vcpu_info_mask(%eax)
+	movb $1, %ss:XEN_vcpu_info_mask(%eax)
 
 1:	popl %eax
 

3.0-stable review patch. If anyone has any objections, please let me know.

------------------

From: "Rafael J. Wysocki" <[email protected]>

commit 249bfb83cf8ba658955f0245ac3981d941f746ee upstream.

Devices are added to pci_pme_list when drivers use pci_enable_wake() or pci_wake_from_d3(), but they aren't removed from the list unless the driver explicitly disables wakeup. Many drivers never disable wakeup, so their devices remain on the list even after they are removed, e.g., via hotplug. A subsequent PME poll will oops when it tries to touch the device.

This patch disables PME# on a device before removing it, which removes the device from pci_pme_list. This is safe even if the device never had PME# enabled.

This oops can be triggered by unplugging a Thunderbolt ethernet adapter on a Macbook Pro, as reported by Daniel below.

[bhelgaas: changelog]
Reference: http://lkml.kernel.org/r/CAMVG2svG21yiM1wkH4_2pen2n+cr2-Zv7TbH3Gj+8MwevZjDbw@mail.gmail.com

---
 drivers/pci/remove.c |    2 ++
 1 file changed, 2 insertions(+)

@@ -19,6 +19,8 @@ static void pci_free_resources(struct pc
 
 static void pci_stop_dev(struct pci_dev *dev)
 {
+	pci_pme_active(dev, false);
+
 	if (dev->is_added) {
 		pci_proc_detach_device(dev);
 		pci_remove_sysfs_dev_files(dev);

3.0-stable review patch. If anyone has any objections, please let me know.

------------------

From: Alexander Duyck <[email protected]>

commit ae1c07a6b7ced6c0c94c99e3b53f4e7856fa8bff upstream.

For some reason the reading of the RQDPC register was being artificially limited to 4K. Instead of limiting the value we should read the value and add the full amount. Otherwise this can lead to a misleading number of dropped packets when the actual value is in fact much higher.

---
 drivers/net/igb/igb_main.c |    8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

@@ -4521,11 +4521,13 @@ void igb_update_stats(struct igb_adapter
 	bytes = 0;
 	packets = 0;
 	for (i = 0; i < adapter->num_rx_queues; i++) {
-		u32 rqdpc_tmp = rd32(E1000_RQDPC(i)) & 0x0FFF;
+		u32 rqdpc = rd32(E1000_RQDPC(i));
 		struct igb_ring *ring = adapter->rx_ring[i];
 
-		ring->rx_stats.drops += rqdpc_tmp;
-		net_stats->rx_fifo_errors += rqdpc_tmp;
+		if (rqdpc) {
+			ring->rx_stats.drops += rqdpc;
+			net_stats->rx_fifo_errors += rqdpc;
+		}
 
 		do {
 			start = u64_stats_fetch_begin_bh(&ring->rx_syncp);

Patches applied cleanly to 3.0.64, 3.4.31, and 3.7.8. Compiled and booted on the following systems:
HP EliteBook 6930p Intel(R) Core(TM)2 Duo CPU T9400 @ 2.53GHz HP ProBook 6475b AMD A10-4600M APU with Radeon(tm) HD Graphics

Reviewed patches

Cross-compile tests results:
alpha: defconfig passed on all
arm: defconfig passed on all
arm64: not applicable to 3.0.y, 3.4.y. defconfig passed on 3.7.y
c6x: not applicable to 3.0.y, defconfig passed on 3.4.y, and 3.7.y.
mips: defconfig passed on all
mipsel: defconfig passed on all
powerpc: wii_defconfig passed on all
sh: defconfig passed on all
sparc: defconfig passed on all
tile: tilegx_defconfig passed on all

-- Shuah

Thanks for testing all of these and letting us know.

greg k-h