Messages in this thread Patch in this message | | | Date | Tue, 07 Dec 2010 16:04:33 -0800 | From | Greg KH <> | Subject | [34/44] Limit sysctl_tcp_mem and sysctl_udp_mem initializers to prevent integer overflows. |
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2.6.27-stable review patch. If anyone has any objections, please let us know.
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From: Robin Holt <holt@sgi.com>
[ 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 <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 @@ -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;
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