[PATCH] resource: make sure requested range intersects root range

[Octavian Purdila]

When the requested and root ranges do not intersect the logic in
__reserve_region_with_split will cause an infinite recursion which
will overflow the stack as seen in the warning bellow.

This particular stack overflow was caused by requesting the
(100000000-107ffffff) range while the root range was (0-ffffffff). In
this case __request_resource would return the whole root range as
conflict range (i.e. 0-ffffffff). Then, the logic in
__reserve_region_with_split would continue the recursion requesting
the new range as (conflict->end+1, end) which incidentally in this
case equals the originally requested range.

This patch aborts looking for a usable range when the requested one is
completely outside the root range to avoid the infinite recursion, and
since this indicates a problem in the layers above, it also prints an
error message indicating the requested and root range in order to make
the problem more easily traceable.

[    5.968374] WARNING: at kernel/sched.c:4129 sub_preempt_count+0x63/0x89()
[    5.975150] Modules linked in:
[    5.978184] Pid: 1, comm: swapper Not tainted 3.0.22-mid27-00004-gb72c817 #46
[    5.985324] Call Trace:
[    5.987759]  [<c1039dfc>] ? console_unlock+0x17b/0x18d
[    5.992891]  [<c1039620>] warn_slowpath_common+0x48/0x5d
[    5.998194]  [<c1031758>] ? sub_preempt_count+0x63/0x89
[    6.003412]  [<c1039644>] warn_slowpath_null+0xf/0x13
[    6.008453]  [<c1031758>] sub_preempt_count+0x63/0x89
[    6.013499]  [<c14d60c4>] _raw_spin_unlock+0x27/0x3f
[    6.018453]  [<c10c6349>] add_partial+0x36/0x3b
[    6.022973]  [<c10c7c0a>] deactivate_slab+0x96/0xb4
[    6.027842]  [<c14cf9d9>] __slab_alloc.isra.54.constprop.63+0x204/0x241
[    6.034456]  [<c103f78f>] ? kzalloc.constprop.5+0x29/0x38
[    6.039842]  [<c103f78f>] ? kzalloc.constprop.5+0x29/0x38
[    6.045232]  [<c10c7dc9>] kmem_cache_alloc_trace+0x51/0xb0
[    6.050710]  [<c103f78f>] ? kzalloc.constprop.5+0x29/0x38
[    6.056100]  [<c103f78f>] kzalloc.constprop.5+0x29/0x38
[    6.061320]  [<c17b45e9>] __reserve_region_with_split+0x1c/0xd1
[    6.067230]  [<c17b4693>] __reserve_region_with_split+0xc6/0xd1
...
[    7.179057]  [<c17b4693>] __reserve_region_with_split+0xc6/0xd1
[    7.184970]  [<c17b4779>] reserve_region_with_split+0x30/0x42
[    7.190709]  [<c17a8ebf>] e820_reserve_resources_late+0xd1/0xe9
[    7.196623]  [<c17c9526>] pcibios_resource_survey+0x23/0x2a
[    7.202184]  [<c17cad8a>] pcibios_init+0x23/0x35
[    7.206789]  [<c17ca574>] pci_subsys_init+0x3f/0x44
[    7.211659]  [<c1002088>] do_one_initcall+0x72/0x122
[    7.216615]  [<c17ca535>] ? pci_legacy_init+0x3d/0x3d
[    7.221659]  [<c17a27ff>] kernel_init+0xa6/0x118
[    7.226265]  [<c17a2759>] ? start_kernel+0x334/0x334
[    7.231223]  [<c14d7482>] kernel_thread_helper+0x6/0x10

Cc: Ram Pai <linuxram@xxxxxxxxxx>
Cc: Jesse Barnes <jbarnes@xxxxxxxxxxxxxxxx>

Signed-off-by: Octavian Purdila <octavian.purdila@xxxxxxxxx>
---
 kernel/resource.c |    8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/kernel/resource.c b/kernel/resource.c
index e1d2b8e..54402be 100644
--- a/kernel/resource.c
+++ b/kernel/resource.c
@@ -789,7 +789,13 @@ void __init reserve_region_with_split(struct resource *root,
 		const char *name)
 {
 	write_lock(&resource_lock);
-	__reserve_region_with_split(root, start, end, name);
+	if (start > root->end || end < root->start)
+		pr_err("Requested range (0x%llx-0x%llx) not in root range (0x%llx-0x%llx)\n",
+		       (unsigned long long)start, (unsigned long long)end,
+		       (unsigned long long)root->start,
+		       (unsigned long long)root->end);
+	else
+		__reserve_region_with_split(root, start, end, name);
 	write_unlock(&resource_lock);
 }
 
-- 
1.7.9.5

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