This is a note to let you know that I've just added the patch titled
kernel/resource.c: fix stack overflow in __reserve_region_with_split()
to the 3.0-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
kernel-resource.c-fix-stack-overflow-in-__reserve_region_with_split.patch
and it can be found in the queue-3.0 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <[email protected]> know about it.
>From 4965f5667f36a95b41cda6638875bc992bd7d18b Mon Sep 17 00:00:00 2001
From: T Makphaibulchoke <[email protected]>
Date: Thu, 4 Oct 2012 17:16:55 -0700
Subject: kernel/resource.c: fix stack overflow in __reserve_region_with_split()
From: T Makphaibulchoke <[email protected]>
commit 4965f5667f36a95b41cda6638875bc992bd7d18b upstream.
Using a recursive call add a non-conflicting region in
__reserve_region_with_split() could result in a stack overflow in the case
that the recursive calls are too deep. Convert the recursive calls to an
iterative loop to avoid the problem.
Tested on a machine containing 135 regions. The kernel no longer panicked
with stack overflow.
Also tested with code arbitrarily adding regions with no conflict,
embedding two consecutive conflicts and embedding two non-consecutive
conflicts.
Signed-off-by: T Makphaibulchoke <[email protected]>
Reviewed-by: Ram Pai <[email protected]>
Cc: Paul Gortmaker <[email protected]>
Cc: Wei Yang <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
Cc: Jiri Slaby <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>
---
kernel/resource.c | 52 +++++++++++++++++++++++++++++++++++++++-------------
1 file changed, 39 insertions(+), 13 deletions(-)
--- a/kernel/resource.c
+++ b/kernel/resource.c
@@ -736,6 +736,7 @@ static void __init __reserve_region_with
struct resource *parent = root;
struct resource *conflict;
struct resource *res = kzalloc(sizeof(*res), GFP_ATOMIC);
+ struct resource *next_res = NULL;
if (!res)
return;
@@ -745,21 +746,46 @@ static void __init __reserve_region_with
res->end = end;
res->flags = IORESOURCE_BUSY;
- conflict = __request_resource(parent, res);
- if (!conflict)
- return;
-
- /* failed, split and try again */
- kfree(res);
+ while (1) {
- /* conflict covered whole area */
- if (conflict->start <= start && conflict->end >= end)
- return;
+ conflict = __request_resource(parent, res);
+ if (!conflict) {
+ if (!next_res)
+ break;
+ res = next_res;
+ next_res = NULL;
+ continue;
+ }
+
+ /* conflict covered whole area */
+ if (conflict->start <= res->start &&
+ conflict->end >= res->end) {
+ kfree(res);
+ WARN_ON(next_res);
+ break;
+ }
+
+ /* failed, split and try again */
+ if (conflict->start > res->start) {
+ end = res->end;
+ res->end = conflict->start - 1;
+ if (conflict->end < end) {
+ next_res = kzalloc(sizeof(*next_res),
+ GFP_ATOMIC);
+ if (!next_res) {
+ kfree(res);
+ break;
+ }
+ next_res->name = name;
+ next_res->start = conflict->end + 1;
+ next_res->end = end;
+ next_res->flags = IORESOURCE_BUSY;
+ }
+ } else {
+ res->start = conflict->end + 1;
+ }
+ }
- if (conflict->start > start)
- __reserve_region_with_split(root, start, conflict->start-1,
name);
- if (conflict->end < end)
- __reserve_region_with_split(root, conflict->end+1, end, name);
}
void __init reserve_region_with_split(struct resource *root,
Patches currently in stable-queue which might be from [email protected] are
queue-3.0/kernel-resource.c-fix-stack-overflow-in-__reserve_region_with_split.patch
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