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[PATCH 3.14 73/79] genirq: Fix race in register_irq_proc()

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From Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Newsgroups linux.kernel
Subject [PATCH 3.14 73/79] genirq: Fix race in register_irq_proc()
Date Sun, 18 Oct 2015 05:20:04 +0200
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3.14-stable review patch.  If anyone has any objections, please let me know.

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

From: Ben Hutchings <ben@decadent.org.uk>

commit 95c2b17534654829db428f11bcf4297c059a2a7e upstream.

Per-IRQ directories in procfs are created only when a handler is first
added to the irqdesc, not when the irqdesc is created.  In the case of
a shared IRQ, multiple tasks can race to create a directory.  This
race condition seems to have been present forever, but is easier to
hit with async probing.

Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
Link: http://lkml.kernel.org/r/1443266636.2004.2.camel@decadent.org.uk
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 kernel/irq/proc.c |   19 +++++++++++++++++--
 1 file changed, 17 insertions(+), 2 deletions(-)

--- a/kernel/irq/proc.c
+++ b/kernel/irq/proc.c
@@ -12,6 +12,7 @@
 #include <linux/seq_file.h>
 #include <linux/interrupt.h>
 #include <linux/kernel_stat.h>
+#include <linux/mutex.h>
 
 #include "internals.h"
 
@@ -326,18 +327,29 @@ void register_handler_proc(unsigned int
 
 void register_irq_proc(unsigned int irq, struct irq_desc *desc)
 {
+	static DEFINE_MUTEX(register_lock);
 	char name [MAX_NAMELEN];
 
-	if (!root_irq_dir || (desc->irq_data.chip == &no_irq_chip) || desc->dir)
+	if (!root_irq_dir || (desc->irq_data.chip == &no_irq_chip))
 		return;
 
+	/*
+	 * irq directories are registered only when a handler is
+	 * added, not when the descriptor is created, so multiple
+	 * tasks might try to register at the same time.
+	 */
+	mutex_lock(&register_lock);
+
+	if (desc->dir)
+		goto out_unlock;
+
 	memset(name, 0, MAX_NAMELEN);
 	sprintf(name, "%d", irq);
 
 	/* create /proc/irq/1234 */
 	desc->dir = proc_mkdir(name, root_irq_dir);
 	if (!desc->dir)
-		return;
+		goto out_unlock;
 
 #ifdef CONFIG_SMP
 	/* create /proc/irq/<irq>/smp_affinity */
@@ -358,6 +370,9 @@ void register_irq_proc(unsigned int irq,
 
 	proc_create_data("spurious", 0444, desc->dir,
 			 &irq_spurious_proc_fops, (void *)(long)irq);
+
+out_unlock:
+	mutex_unlock(&register_lock);
 }
 
 void unregister_irq_proc(unsigned int irq, struct irq_desc *desc)


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[PATCH 3.14 00/79] 3.14.55-stable review Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2015-10-18 05:10 +0200
  [PATCH 3.14 50/79] ipvs: do not use random local source address for tunnels Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2015-10-18 05:10 +0200
  [PATCH 3.14 69/79] vfs: Test for and handle paths that are unreachable from their mnt_root Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2015-10-18 05:10 +0200
  [PATCH 3.14 38/79] netfilter: nf_conntrack: Support expectations in different zones Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2015-10-18 05:10 +0200
  [PATCH 3.14 45/79] USB: whiteheat: fix potential null-deref at probe Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2015-10-18 05:10 +0200
  [PATCH 3.14 44/79] drm: Reject DRI1 hw lock ioctl functions for kms drivers Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2015-10-18 05:10 +0200
  [PATCH 3.14 07/79] perf header: Fixup reading of HEADER_NRCPUS feature Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2015-10-18 05:10 +0200
  [PATCH 3.14 54/79] regmap: debugfs: Ensure we dont underflow when printing access masks Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2015-10-18 05:10 +0200
  [PATCH 3.14 08/79] hwmon: (nct6775) Swap STEP_UP_TIME and STEP_DOWN_TIME registers for most chips Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2015-10-18 05:10 +0200
  [PATCH 3.14 46/79] usb: xhci: Clear XHCI_STATE_DYING on start Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2015-10-18 05:10 +0200
  [PATCH 3.14 41/79] disabling oplocks/leases via module parm enable_oplocks broken for SMB3 Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2015-10-18 05:10 +0200
  [PATCH 3.14 37/79] dm raid: fix round up of default region size Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2015-10-18 05:10 +0200
  [PATCH 3.14 39/79] netfilter: ctnetlink: put back references to master ct and expect objects Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2015-10-18 05:10 +0200
  [PATCH 3.14 63/79] staging: comedi: usbduxsigma: dont clobber ao_timer in command test Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2015-10-18 05:10 +0200
  [PATCH 3.14 35/79] staging: ion: fix corruption of ion_import_dma_buf Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2015-10-18 05:10 +0200
  [PATCH 3.14 49/79] Initialize msg/shm IPC objects before doing ipc_addid() Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2015-10-18 05:10 +0200
  [PATCH 3.14 70/79] arm64: readahead: fault retry breaks mmap file read random detection Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2015-10-18 05:10 +0200
  [PATCH 3.14 48/79] usb: xhci: Add support for URB_ZERO_PACKET to bulk/sg transfers Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2015-10-18 05:10 +0200
  [PATCH 3.14 42/79] drm/qxl: only report first monitor as connected if we have no state Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2015-10-18 05:10 +0200
  [PATCH 3.14 52/79] cifs: use server timestamp for ntlmv2 authentication Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2015-10-18 05:10 +0200
  [PATCH 3.14 68/79] dcache: Handle escaped paths in prepend_path Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2015-10-18 05:10 +0200
  [PATCH 3.14 65/79] powerpc/MSI: Fix race condition in tearing down MSI interrupts Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2015-10-18 05:10 +0200
  [PATCH 3.14 56/79] security: fix typo in security_task_prctl Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2015-10-18 05:20 +0200
  [PATCH 3.14 34/79] dm btree: add ref counting ops for the leaves of top level btrees Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2015-10-18 05:20 +0200
  [PATCH 3.14 13/79] dmaengine: dw: properly read DWC_PARAMS register Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2015-10-18 05:20 +0200
  [PATCH 3.14 76/79] dm cache: fix NULL pointer when switching from cleaner policy Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2015-10-18 05:20 +0200
  [PATCH 3.14 36/79] USB: option: add ZTE PIDs Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2015-10-18 05:20 +0200
  [PATCH 3.14 62/79] staging: comedi: usbduxsigma: dont clobber ai_timer in command test Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2015-10-18 05:20 +0200
  [PATCH 3.14 04/79] perf tools: Fix copying of /proc/kcore Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2015-10-18 05:20 +0200
  [PATCH 3.14 30/79] ASoC: dwc: correct irq clear method Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2015-10-18 05:20 +0200
  [PATCH 3.14 53/79] mtd: pxa3xx_nand: add a default chunk size Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2015-10-18 05:20 +0200
  [PATCH 3.14 72/79] fib_rules: Fix dump_rules() not to exit early Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2015-10-18 05:20 +0200
  [PATCH 3.14 78/79] mm/slab: fix unexpected index mapping result of kmalloc_size(INDEX_NODE+1) Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2015-10-18 05:20 +0200
  [PATCH 3.14 06/79] perf stat: Get correct cpu id for print_aggr Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2015-10-18 05:20 +0200
  [PATCH 3.14 58/79] usb: Add device quirk for Logitech PTZ cameras Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2015-10-18 05:20 +0200
  [PATCH 3.14 74/79] jbd2: avoid infinite loop when destroying aborted journal Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2015-10-18 05:20 +0200
  [PATCH 3.14 27/79] ALSA: hda - Apply SPDIF pin ctl to MacBookPro 12,1 Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2015-10-18 05:20 +0200
  [PATCH 3.14 55/79] regmap: debugfs: Dont bother actually printing when calculating max length Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2015-10-18 05:20 +0200
  [PATCH 3.14 29/79] ASoC: fix broken pxa SoC support Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2015-10-18 05:20 +0200
  [PATCH 3.14 59/79] USB: Add reset-resume quirk for two Plantronics usb headphones. Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2015-10-18 05:20 +0200
  [PATCH 3.14 33/79] Btrfs: update fix for read corruption of compressed and shared extents Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2015-10-18 05:20 +0200
  [PATCH 3.14 61/79] arch,hexagon: Convert smp_mb__*() Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2015-10-18 05:20 +0200
  [PATCH 3.14 57/79] usb: Use the USB_SS_MULT() macro to get the burst multiplier. Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2015-10-18 05:20 +0200
  [PATCH 3.14 09/79] ARM: fix Thumb2 signal handling when ARMv6 is enabled Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2015-10-18 05:20 +0200
  [PATCH 3.14 77/79] staging: speakup: fix speakup-r regression Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2015-10-18 05:20 +0200
  [PATCH 3.14 05/79] perf hists: Update the column width for the "srcline" sort key Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2015-10-18 05:20 +0200
  [PATCH 3.14 32/79] Btrfs: fix read corruption of compressed and shared extents Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2015-10-18 05:20 +0200
  [PATCH 3.14 31/79] btrfs: skip waiting on ordered range for special files Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2015-10-18 05:20 +0200
  [PATCH 3.14 03/79] iser-target: remove command with state ISTATE_REMOVE Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2015-10-18 05:20 +0200
  [PATCH 3.14 75/79] clk: ti: fix dual-registration of uart4_ick Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2015-10-18 05:20 +0200
  [PATCH 3.14 25/79] mm: hugetlbfs: skip shared VMAs when unmapping private pages to satisfy a fault Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2015-10-18 05:20 +0200
  [PATCH 3.14 71/79] m68k: Define asmlinkage_protect Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2015-10-18 05:20 +0200
  [PATCH 3.14 60/79] MIPS: dma-default: Fix 32-bit fall back to GFP_DMA Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2015-10-18 05:20 +0200
  [PATCH 3.14 28/79] ASoC: pxa: pxa2xx-ac97: fix dma requestor lines Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2015-10-18 05:20 +0200
  [PATCH 3.14 73/79] genirq: Fix race in register_irq_proc() Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2015-10-18 05:20 +0200
  [PATCH 3.14 10/79] ARM: 8429/1: disable GCC SRA optimization Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2015-10-18 05:30 +0200
  [PATCH 3.14 18/79] Use WARN_ON_ONCE for missing X86_FEATURE_NRIPS Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2015-10-18 05:30 +0200
  [PATCH 3.14 22/79] sched/core: Fix TASK_DEAD race in finish_task_switch() Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2015-10-18 05:30 +0200
  [PATCH 3.14 14/79] x86/apic: Serialize LVTT and TSC_DEADLINE writes Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2015-10-18 05:30 +0200
  [PATCH 3.14 21/79] x86/xen: Support kexec/kdump in HVM guests by doing a soft reset Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2015-10-18 05:30 +0200
  [PATCH 3.14 26/79] ALSA: synth: Fix conflicting OSS device registration on AWE32 Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2015-10-18 05:30 +0200
  [PATCH 3.14 01/79] kvm: fix zero length mmio searching Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2015-10-18 05:30 +0200
  [PATCH 3.14 20/79] x86/mm: Set NX on gap between __ex_table and rodata Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2015-10-18 05:30 +0200
  [PATCH 3.14 12/79] ARM: dts: omap5-uevm.dts: fix i2c5 pinctrl offsets Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2015-10-18 05:30 +0200
  [PATCH 3.14 15/79] x86/platform: Fix Geode LX timekeeping in the generic x86 build Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2015-10-18 05:30 +0200
  [PATCH 3.14 11/79] windfarm: decrement client count when unregistering Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2015-10-18 05:30 +0200
  [PATCH 3.14 23/79] spi: Fix documentation of spi_alloc_master() Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2015-10-18 05:30 +0200
  [PATCH 3.14 02/79] scsi: fix scsi_error_handler vs. scsi_host_dev_release race Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2015-10-18 05:30 +0200
  [PATCH 3.14 17/79] x86/nmi/64: Fix a paravirt stack-clobbering bug in the NMI code Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2015-10-18 05:30 +0200
  [PATCH 3.14 24/79] spi: spi-pxa2xx: Check status register to determine if SSSR_TINT is disabled Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2015-10-18 05:50 +0200
  [PATCH 3.14 19/79] x86/efi: Fix boot crash by mapping EFI memmap entries bottom-up at runtime, instead of top-down Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2015-10-18 05:50 +0200
  Re: [PATCH 3.14 00/79] 3.14.55-stable review Guenter Roeck <linux@roeck-us.net> - 2015-10-19 06:20 +0200
    Re: [PATCH 3.14 00/79] 3.14.55-stable review Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2015-10-19 17:20 +0200
      Re: [PATCH 3.14 00/79] 3.14.55-stable review Richard Kuo <rkuo@codeaurora.org> - 2015-10-19 21:20 +0200
        Re: [PATCH 3.14 00/79] 3.14.55-stable review Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2015-10-19 22:10 +0200
          Re: [PATCH 3.14 00/79] 3.14.55-stable review Richard Kuo <rkuo@codeaurora.org> - 2015-10-19 23:40 +0200
  Re: [PATCH 3.14 00/79] 3.14.55-stable review Shuah Khan <shuahkh@osg.samsung.com> - 2015-10-19 17:30 +0200

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