The patch titled
/proc/kcore: work around a BUG()
has been added to the -mm tree. Its filename is
proc-kcore-work-around-a-bug.patch
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------------------------------------------------------
Subject: /proc/kcore: work around a BUG()
From: KAMEZAWA Hiroyuki <kamezawa.hiroyu@xxxxxxxxxxxxxx>
Works around a BUG() which is triggered when the kernel accesses holes in
vmalloc regions.
BUG: unable to handle kernel paging request at fa54c000
IP: [<c04f687a>] read_kcore+0x260/0x31a
*pde = 3540b067 *pte = 00000000
Oops: 0000 [#1] SMP
last sysfs file: /sys/devices/pci0000:00/0000:00:1c.2/0000:03:00.0/ieee80211/phy0/rfkill0/state
Modules linked in: fuse sco bridge stp llc bnep l2cap bluetooth sunrpc nf_conntrack_ftp ip6t_REJECT nf_conntrack_ipv6 ip6table_filter ip6_tables ipv6 cpufreq_ondemand acpi_cpufreq dm_multipath uinput usb_storage arc4 ecb snd_hda_codec_realtek snd_hda_intel ath5k snd_hda_codec snd_hwdep iTCO_wdt snd_pcm iTCO_vendor_support pcspkr i2c_i801 mac80211 joydev snd_timer serio_raw r8169 snd soundcore mii snd_page_alloc ath cfg80211 ata_generic i915 drm i2c_algo_bit i2c_core video output [last unloaded: scsi_wait_scan]
Sep 4 12:45:16 tuxedu kernel: Pid: 2266, comm: cat Not tainted (2.6.31-rc8 #2) Joybook Lite U101
EIP: 0060:[<c04f687a>] EFLAGS: 00010286 CPU: 0
EIP is at read_kcore+0x260/0x31a
EAX: f5e5ea00 EBX: fa54d000 ECX: 00000400 EDX: 00001000
ESI: fa54c000 EDI: f44ad000 EBP: e4533f4c ESP: e4533f24
DS: 007b ES: 007b FS: 00d8 GS: 0033 SS: 0068
Process cat (pid: 2266, ti=e4532000 task=f09d19a0 task.ti=e4532000)
Stack:
00005000 00000000 f44ad000 09d9c000 00003000 fa54c000 00001000 f6d16f60
e4520b80 fffffffb e4533f70 c04ef8eb e4533f98 00008000 09d97000 c04f661a
e4520b80 09d97000 c04ef88c e4533f8c c04ba531 e4533f98 c04c0930 e4520b80
Call Trace:
[<c04ef8eb>] ? proc_reg_read+0x5f/0x73
[<c04f661a>] ? read_kcore+0x0/0x31a
[<c04ef88c>] ? proc_reg_read+0x0/0x73
[<c04ba531>] ? vfs_read+0x82/0xe1
[<c04c0930>] ? path_put+0x1a/0x1d
[<c04ba62e>] ? sys_read+0x40/0x62
[<c0403298>] ? sysenter_do_call+0x12/0x2d
Code: 39 f3 89 ca 0f 43 f3 89 fb 29 f2 29 f3 39 cf 0f 46 d3 29 55 dc 8d 1c 32 f6 40 0c 01 75 18 89 d1 89 f7 c1 e9 02 2b 7d ec 03 7d e0 <f3> a5 89 d1 83 e1 03 74 02 f3 a4 8b 00 83 7d dc 00 74 04 85 c0
EIP: [<c04f687a>] read_kcore+0x260/0x31a SS:ESP 0068:e4533f24
CR2: 00000000fa54c000
To access vmalloc area which may have memory holes, copy_from_user is
useful. So this:
# cat /proc/kcore > /dev/null
will not panic.
This is a minimal fix, suitable for 2.6.30.x and 2.6.31. More extensive
/proc/kcore changes are planned for 2.6.32.
Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@xxxxxxxxxxxxxx>
Tested-by: Nick Craig-Wood <nick@xxxxxxxxxxxxxx>
Cc: Pekka Enberg <penberg@xxxxxxxxxxxxxx>
Reported-by: <kbowa@xxxxxxxxxx>
Cc: <stable@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
fs/proc/kcore.c | 8 +++++++-
1 file changed, 7 insertions(+), 1 deletion(-)
diff -puN fs/proc/kcore.c~proc-kcore-work-around-a-bug fs/proc/kcore.c
--- a/fs/proc/kcore.c~proc-kcore-work-around-a-bug
+++ a/fs/proc/kcore.c
@@ -361,7 +361,13 @@ read_kcore(struct file *file, char __use
/* don't dump ioremap'd stuff! (TA) */
if (m->flags & VM_IOREMAP)
continue;
- memcpy(elf_buf + (vmstart - start),
+ /*
+ * we may access memory holes, then use
+ * ex_table. checking return value just for
+ * avoid warnings.
+ */
+ vmsize = __copy_from_user_inatomic(
+ elf_buf + (vmstart - start),
(char *)vmstart, vmsize);
}
read_unlock(&vmlist_lock);
_
Patches currently in -mm which might be from kamezawa.hiroyu@xxxxxxxxxxxxxx are
proc-kcore-work-around-a-bug.patch
mm-clean-up-page_remove_rmap.patch
vmscan-throttle-direct-reclaim-when-too-many-pages-are-isolated-already.patch
mm-remove-__addsub_zone_page_state.patch
vmscan-dont-attempt-to-reclaim-anon-page-in-lumpy-reclaim-when-no-swap-space-is-avilable.patch
ksm-add-mmu_notifier-set_pte_at_notify.patch
ksm-first-tidy-up-madvise_vma.patch
ksm-define-madv_mergeable-and-madv_unmergeable.patch
ksm-the-mm-interface-to-ksm.patch
ksm-no-debug-in-page_dup_rmap.patch
ksm-identify-pageksm-pages.patch
ksm-kernel-samepage-merging.patch
ksm-prevent-mremap-move-poisoning.patch
ksm-change-copyright-message.patch
ksm-change-ksm-nice-level-to-be-5.patch
vmalloc-unmap-vmalloc-area-after-hiding-it.patch
kcore-fix-vread-vwrite-to-be-aware-of-holes.patch
kcore-fix-vread-vwrite-to-be-aware-of-holes-update.patch
kcore-proc-kcore-should-use-vread.patch
mm-add_to_swap_cache-must-not-sleep.patch
mm-add_to_swap_cache-does-not-return-eexist.patch
memory-hotplug-fix-updating-of-num_physpages-for-hot-plugged-memory.patch
mm-vmscan-rename-zone_nr_pages-to-zone_lru_nr_pages.patch
mm-do-batched-scans-for-mem_cgroup.patch
oom-move-oom_adj-value-from-task_struct-to-signal_struct.patch
oom-make-oom_score-to-per-process-value.patch
oom-oom_kill-doesnt-kill-vfork-parentor-child.patch
oom-fix-oom_adjust_write-input-sanity-check.patch
mm-fix-numa-accounting-in-numastattxt.patch
kcore-fix-proc-kcores-statst_size.patch
kcore-use-usual-list-for-kclist.patch
kcore-add-kclist-types.patch
kcore-register-vmalloc-area-in-generic-way.patch
kcore-register-text-area-in-generic-way.patch
walk-system-ram-range.patch
kcore-use-registerd-physmem-information.patch
kcore-register-vmemmap-range.patch
kcore-register-vmemmap-range-fix.patch
kcore-register-module-area-in-generic-way.patch
cgroups-support-named-cgroups-hierarchies.patch
cgroups-move-the-cgroup-debug-subsys-into-cgroupc-to-access-internal-state.patch
cgroups-add-a-back-pointer-from-struct-cg_cgroup_link-to-struct-cgroup.patch
cgroups-allow-cgroup-hierarchies-to-be-created-with-no-bound-subsystems.patch
memcg-remove-the-overhead-associated-with-the-root-cgroup.patch
memcg-remove-the-overhead-associated-with-the-root-cgroup-fix.patch
memcg-remove-the-overhead-associated-with-the-root-cgroup-fix-2.patch
memcg-add-comments-explaining-memory-barriers.patch
memcg-add-comments-explaining-memory-barriers-checkpatch-fixes.patch
memory-controller-soft-limit-documentation-v9.patch
memory-controller-soft-limit-interface-v9.patch
memory-controller-soft-limit-organize-cgroups-v9.patch
memory-controller-soft-limit-organize-cgroups-v9-fix.patch
memory-controller-soft-limit-refactor-reclaim-flags-v9.patch
memory-controller-soft-limit-reclaim-on-contention-v9.patch
memory-controller-soft-limit-reclaim-on-contention-v9-fix.patch
memory-controller-soft-limit-reclaim-on-contention-v9-fix-softlimit-css-refcnt-handling.patch
memory-controller-soft-limit-reclaim-on-contention-v9-fix-softlimit-css-refcnt-handling-fix.patch
memcg-improve-resource-counter-scalability.patch
memcg-improve-resource-counter-scalability-v5.patch
memcg-show-swap-usage-in-stat-file.patch
memcg-show-swap-usage-in-stat-file-fix.patch
do_wait-wakeup-optimization-fix-child_wait_callback-eligible_child-usage.patch
do_wait-wakeup-optimization-simplify-task_pid_type.patch
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