lkml.org 
[lkml]   [2010]   [Dec]   [7]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
Date
From
Subject[097/127] Limit sysctl_tcp_mem and sysctl_udp_mem initializers to prevent integer overflows.
2.6.32-stable review patch.  If anyone has any objections, please let us know.

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


From: Robin Holt <holt@sgi.com>

[ Upstream fixed this in a different way. -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 <holt@sgi.com>
To: "David S. Miller" <davem@davemloft.net>
Cc: Willy Tarreau <w@1wt.eu>
Cc: linux-kernel@vger.kernel.org
Cc: netdev@vger.kernel.org
Cc: linux-sctp@vger.kernel.org
Cc: Alexey Kuznetsov <kuznet@ms2.inr.ac.ru>
Cc: "Pekka Savola (ipv6)" <pekkas@netcore.fi>
Cc: James Morris <jmorris@namei.org>
Cc: Hideaki YOSHIFUJI <yoshfuji@linux-ipv6.org>
Cc: Patrick McHardy <kaber@trash.net>
Cc: Vlad Yasevich <vladislav.yasevich@hp.com>
Cc: Sridhar Samudrala <sri@us.ibm.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
---
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
@@ -2940,12 +2940,14 @@ 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
@@ -1832,12 +1832,14 @@ void __init udp_init(void)
udp_table_init(&udp_table);
/* 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.
*/
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_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
@@ -1157,7 +1157,8 @@ 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
*/
@@ -1165,6 +1166,7 @@ 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;



\
 
 \ /
  Last update: 2010-12-08 01:57    [W:0.344 / U:0.620 seconds]
©2003-2018 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site