Subject: [Patch] Limit sysctl_tcp_mem and sysctl_udp_mem initializers to prevent integer overflows. 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@xxxxxxx> To: "David S. Miller" <davem@xxxxxxxxxxxxx> Cc: Willy Tarreau <w@xxxxxx> Cc: linux-kernel@xxxxxxxxxxxxxxx Cc: netdev@xxxxxxxxxxxxxxx Cc: linux-sctp@xxxxxxxxxxxxxxx Cc: Alexey Kuznetsov <kuznet@xxxxxxxxxxxxx> Cc: "Pekka Savola (ipv6)" <pekkas@xxxxxxxxxx> Cc: James Morris <jmorris@xxxxxxxxx> Cc: Hideaki YOSHIFUJI <yoshfuji@xxxxxxxxxxxxxx> Cc: Patrick McHardy <kaber@xxxxxxxxx> Cc: Vlad Yasevich <vladislav.yasevich@xxxxxx> Cc: Sridhar Samudrala <sri@xxxxxxxxxx> --- David, I believe this is also intended for stable. If you agree, please add the stable maintainers to the Cc: list. net/ipv4/tcp.c | 4 +++- net/ipv4/udp.c | 4 +++- net/sctp/protocol.c | 4 +++- 3 files changed, 9 insertions(+), 3 deletions(-) Index: pv1010932/net/ipv4/tcp.c =================================================================== --- pv1010932.orig/net/ipv4/tcp.c 2010-10-02 06:11:59.737449853 -0500 +++ pv1010932/net/ipv4/tcp.c 2010-10-02 06:12:35.445454593 -0500 @@ -3271,12 +3271,14 @@ 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; Index: pv1010932/net/ipv4/udp.c =================================================================== --- pv1010932.orig/net/ipv4/udp.c 2010-10-02 06:11:59.737449853 -0500 +++ pv1010932/net/ipv4/udp.c 2010-10-02 06:12:35.453453784 -0500 @@ -2167,12 +2167,14 @@ void __init udp_init(void) udp_table_init(&udp_table, "UDP"); /* 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; Index: pv1010932/net/sctp/protocol.c =================================================================== --- pv1010932.orig/net/sctp/protocol.c 2010-10-02 06:11:59.000000000 -0500 +++ pv1010932/net/sctp/protocol.c 2010-10-02 06:13:17.727949810 -0500 @@ -1162,7 +1162,8 @@ 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 initializes the data in sctpv6_prot too * Unabashedly stolen from tcp_init */ @@ -1170,6 +1171,7 @@ 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; -- To unsubscribe from this list: send the line "unsubscribe linux-sctp" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
