This is a note to let you know that I've just added the patch titled
Limit sysctl_tcp_mem and sysctl_udp_mem initializers to prevent integer
overflows.
to the 2.6.27-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:
limit-sysctl_tcp_mem-and-sysctl_udp_mem-initializers-to-prevent-integer-overflows.patch
and it can be found in the queue-2.6.27 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <[email protected]> know about it.
>From 92988de9edaa8e54456640dbcd866e74c558c911 Mon Sep 17 00:00:00 2001
From: Robin Holt <[email protected]>
Date: Wed, 20 Oct 2010 02:03:37 +0000
Subject: Limit sysctl_tcp_mem and sysctl_udp_mem initializers to prevent
integer overflows.
From: Robin Holt <[email protected]>
[ Problem was fixed differently upstream. -DaveM ]
On a 16TB x86_64 machine, sysctl_tcp_mem[2], sysctl_udp_mem[2], and
sysctl_sctp_mem[2] can integer overflow. Set limit such that they are
maximized without overflowing.
Signed-off-by: Robin Holt <[email protected]>
To: "David S. Miller" <[email protected]>
Cc: Willy Tarreau <[email protected]>
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: Alexey Kuznetsov <[email protected]>
Cc: "Pekka Savola (ipv6)" <[email protected]>
Cc: James Morris <[email protected]>
Cc: Hideaki YOSHIFUJI <[email protected]>
Cc: Patrick McHardy <[email protected]>
Cc: Vlad Yasevich <[email protected]>
Cc: Sridhar Samudrala <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>
---
net/ipv4/tcp.c | 4 +++-
net/ipv4/udp.c | 4 +++-
net/sctp/protocol.c | 4 +++-
3 files changed, 9 insertions(+), 3 deletions(-)
--- a/net/ipv4/tcp.c
+++ b/net/ipv4/tcp.c
@@ -2754,12 +2754,14 @@ void __init tcp_init(void)
/* Set the pressure threshold to be a fraction of global memory that
* is up to 1/2 at 256 MB, decreasing toward zero with the amount of
- * memory, with a floor of 128 pages.
+ * memory, with a floor of 128 pages, and a ceiling that prevents an
+ * integer overflow.
*/
nr_pages = totalram_pages - totalhigh_pages;
limit = min(nr_pages, 1UL<<(28-PAGE_SHIFT)) >> (20-PAGE_SHIFT);
limit = (limit * (nr_pages >> (20-PAGE_SHIFT))) >> (PAGE_SHIFT-11);
limit = max(limit, 128UL);
+ limit = min(limit, INT_MAX * 4UL / 3 / 2);
sysctl_tcp_mem[0] = limit / 4 * 3;
sysctl_tcp_mem[1] = limit;
sysctl_tcp_mem[2] = sysctl_tcp_mem[0] * 2;
--- a/net/ipv4/udp.c
+++ b/net/ipv4/udp.c
@@ -1722,11 +1722,13 @@ void __init udp_init(void)
/* Set the pressure threshold up by the same strategy of TCP. It is a
* fraction of global memory that is up to 1/2 at 256 MB, decreasing
- * toward zero with the amount of memory, with a floor of 128 pages.
+ * toward zero with the amount of memory, with a floor of 128 pages,
+ * and a ceiling that prevents an integer overflow.
*/
limit = min(nr_all_pages, 1UL<<(28-PAGE_SHIFT)) >> (20-PAGE_SHIFT);
limit = (limit * (nr_all_pages >> (20-PAGE_SHIFT))) >> (PAGE_SHIFT-11);
limit = max(limit, 128UL);
+ limit = min(limit, INT_MAX * 4UL / 3 / 2);
sysctl_udp_mem[0] = limit / 4 * 3;
sysctl_udp_mem[1] = limit;
sysctl_udp_mem[2] = sysctl_udp_mem[0] * 2;
--- a/net/sctp/protocol.c
+++ b/net/sctp/protocol.c
@@ -1179,7 +1179,8 @@ SCTP_STATIC __init int sctp_init(void)
/* Set the pressure threshold to be a fraction of global memory that
* is up to 1/2 at 256 MB, decreasing toward zero with the amount of
- * memory, with a floor of 128 pages.
+ * memory, with a floor of 128 pages, and a ceiling that prevents an
+ * integer overflow.
* Note this initalizes the data in sctpv6_prot too
* Unabashedly stolen from tcp_init
*/
@@ -1187,6 +1188,7 @@ SCTP_STATIC __init int sctp_init(void)
limit = min(nr_pages, 1UL<<(28-PAGE_SHIFT)) >> (20-PAGE_SHIFT);
limit = (limit * (nr_pages >> (20-PAGE_SHIFT))) >> (PAGE_SHIFT-11);
limit = max(limit, 128UL);
+ limit = min(limit, INT_MAX * 4UL / 3 / 2);
sysctl_sctp_mem[0] = limit / 4 * 3;
sysctl_sctp_mem[1] = limit;
sysctl_sctp_mem[2] = sysctl_sctp_mem[0] * 2;
Patches currently in stable-queue which might be from [email protected] are
queue-2.6.27/limit-sysctl_tcp_mem-and-sysctl_udp_mem-initializers-to-prevent-integer-overflows.patch
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