Messages in this thread Patch in this message | | | From | Greg Kroah-Hartman <> | Subject | [ 02/19] net: check net.core.somaxconn sysctl values | Date | Thu, 12 Sep 2013 10:26:11 -0700 |
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3.0-stable review patch. If anyone has any objections, please let me know.
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From: Roman Gushchin <klamm@yandex-team.ru>
[ Upstream commit 5f671d6b4ec3e6d66c2a868738af2cdea09e7509 ]
It's possible to assign an invalid value to the net.core.somaxconn sysctl variable, because there is no checks at all.
The sk_max_ack_backlog field of the sock structure is defined as unsigned short. Therefore, the backlog argument in inet_listen() shouldn't exceed USHRT_MAX. The backlog argument in the listen() syscall is truncated to the somaxconn value. So, the somaxconn value shouldn't exceed 65535 (USHRT_MAX). Also, negative values of somaxconn are meaningless.
before: $ sysctl -w net.core.somaxconn=256 net.core.somaxconn = 256 $ sysctl -w net.core.somaxconn=65536 net.core.somaxconn = 65536 $ sysctl -w net.core.somaxconn=-100 net.core.somaxconn = -100
after: $ sysctl -w net.core.somaxconn=256 net.core.somaxconn = 256 $ sysctl -w net.core.somaxconn=65536 error: "Invalid argument" setting key "net.core.somaxconn" $ sysctl -w net.core.somaxconn=-100 error: "Invalid argument" setting key "net.core.somaxconn"
Based on a prior patch from Changli Gao.
Signed-off-by: Roman Gushchin <klamm@yandex-team.ru> Reported-by: Changli Gao <xiaosuo@gmail.com> Suggested-by: Eric Dumazet <edumazet@google.com> Acked-by: Eric Dumazet <edumazet@google.com> Signed-off-by: David S. Miller <davem@davemloft.net> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> --- net/core/sysctl_net_core.c | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-)
--- a/net/core/sysctl_net_core.c +++ b/net/core/sysctl_net_core.c @@ -19,6 +19,9 @@ #include <net/sock.h> #include <net/net_ratelimit.h> +static int zero = 0; +static int ushort_max = USHRT_MAX; + #ifdef CONFIG_RPS static int rps_sock_flow_sysctl(ctl_table *table, int write, void __user *buffer, size_t *lenp, loff_t *ppos) @@ -192,7 +195,9 @@ static struct ctl_table netns_core_table .data = &init_net.core.sysctl_somaxconn, .maxlen = sizeof(int), .mode = 0644, - .proc_handler = proc_dointvec + .extra1 = &zero, + .extra2 = &ushort_max, + .proc_handler = proc_dointvec_minmax }, { } };
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