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Message-Id: <1520479847-39174-3-git-send-email-keescook@chromium.org> Date: Wed, 7 Mar 2018 19:30:46 -0800 From: Kees Cook <keescook@...omium.org> To: Andrew Morton <akpm@...ux-foundation.org> Cc: Kees Cook <keescook@...omium.org>, linux-kernel@...r.kernel.org, corbet@....net, gustavo@...eddedor.com, rostedt@...dmis.org, Chris Mason <clm@...com>, Josef Bacik <jbacik@...com>, David Sterba <dsterba@...e.com>, "David S. Miller" <davem@...emloft.net>, Alexey Kuznetsov <kuznet@....inr.ac.ru>, Hideaki YOSHIFUJI <yoshfuji@...ux-ipv6.org>, Ingo Molnar <mingo@...nel.org>, Peter Zijlstra <peterz@...radead.org>, Thomas Gleixner <tglx@...utronix.de>, Masahiro Yamada <yamada.masahiro@...ionext.com>, Borislav Petkov <bp@...e.de>, Josh Poimboeuf <jpoimboe@...hat.com>, Randy Dunlap <rdunlap@...radead.org>, Ian Abbott <abbotti@....co.uk>, "Tobin C. Harding" <me@...in.cc>, Sergey Senozhatsky <sergey.senozhatsky.work@...il.com>, Petr Mladek <pmladek@...e.com>, Andy Shevchenko <andriy.shevchenko@...ux.intel.com>, Pantelis Antoniou <pantelis.antoniou@...sulko.com>, linux-btrfs@...r.kernel.org, netdev@...r.kernel.org, kernel-hardening@...ts.openwall.com Subject: [PATCH 2/3] net: Remove accidental VLAs from proc buffers In the quest to remove all stack VLAs from the kernel[1], this refactors the stack array size calculation to avoid using max(), which makes the compiler think the size isn't fixed. [1] https://lkml.org/lkml/2018/3/7/621 Signed-off-by: Kees Cook <keescook@...omium.org> --- net/ipv4/proc.c | 10 ++++------ net/ipv6/proc.c | 10 ++++------ 2 files changed, 8 insertions(+), 12 deletions(-) diff --git a/net/ipv4/proc.c b/net/ipv4/proc.c index dc5edc8f7564..c23c43803435 100644 --- a/net/ipv4/proc.c +++ b/net/ipv4/proc.c @@ -46,8 +46,6 @@ #include <net/sock.h> #include <net/raw.h> -#define TCPUDP_MIB_MAX max_t(u32, UDP_MIB_MAX, TCP_MIB_MAX) - /* * Report socket allocation statistics [mea@....fi] */ @@ -400,11 +398,11 @@ static int snmp_seq_show_ipstats(struct seq_file *seq, void *v) static int snmp_seq_show_tcp_udp(struct seq_file *seq, void *v) { - unsigned long buff[TCPUDP_MIB_MAX]; + unsigned long buff[SIMPLE_MAX(UDP_MIB_MAX, TCP_MIB_MAX)]; struct net *net = seq->private; int i; - memset(buff, 0, TCPUDP_MIB_MAX * sizeof(unsigned long)); + memset(buff, 0, sizeof(buff)); seq_puts(seq, "\nTcp:"); for (i = 0; snmp4_tcp_list[i].name; i++) @@ -421,7 +419,7 @@ static int snmp_seq_show_tcp_udp(struct seq_file *seq, void *v) seq_printf(seq, " %lu", buff[i]); } - memset(buff, 0, TCPUDP_MIB_MAX * sizeof(unsigned long)); + memset(buff, 0, sizeof(buff)); snmp_get_cpu_field_batch(buff, snmp4_udp_list, net->mib.udp_statistics); @@ -432,7 +430,7 @@ static int snmp_seq_show_tcp_udp(struct seq_file *seq, void *v) for (i = 0; snmp4_udp_list[i].name; i++) seq_printf(seq, " %lu", buff[i]); - memset(buff, 0, TCPUDP_MIB_MAX * sizeof(unsigned long)); + memset(buff, 0, sizeof(buff)); /* the UDP and UDP-Lite MIBs are the same */ seq_puts(seq, "\nUdpLite:"); diff --git a/net/ipv6/proc.c b/net/ipv6/proc.c index b67814242f78..5b0874c26802 100644 --- a/net/ipv6/proc.c +++ b/net/ipv6/proc.c @@ -30,10 +30,8 @@ #include <net/transp_v6.h> #include <net/ipv6.h> -#define MAX4(a, b, c, d) \ - max_t(u32, max_t(u32, a, b), max_t(u32, c, d)) -#define SNMP_MIB_MAX MAX4(UDP_MIB_MAX, TCP_MIB_MAX, \ - IPSTATS_MIB_MAX, ICMP_MIB_MAX) +#define SNMP_MIB_MAX SIMPLE_MAX(SIMPLE_MAX(UDP_MIB_MAX, TCP_MIB_MAX), \ + SIMPLE_MAX(IPSTATS_MIB_MAX, ICMP_MIB_MAX)) static int sockstat6_seq_show(struct seq_file *seq, void *v) { @@ -199,7 +197,7 @@ static void snmp6_seq_show_item(struct seq_file *seq, void __percpu *pcpumib, int i; if (pcpumib) { - memset(buff, 0, sizeof(unsigned long) * SNMP_MIB_MAX); + memset(buff, 0, sizeof(buff)); snmp_get_cpu_field_batch(buff, itemlist, pcpumib); for (i = 0; itemlist[i].name; i++) @@ -218,7 +216,7 @@ static void snmp6_seq_show_item64(struct seq_file *seq, void __percpu *mib, u64 buff64[SNMP_MIB_MAX]; int i; - memset(buff64, 0, sizeof(u64) * SNMP_MIB_MAX); + memset(buff64, 0, sizeof(buff64)); snmp_get_cpu_field64_batch(buff64, itemlist, mib, syncpoff); for (i = 0; itemlist[i].name; i++) -- 2.7.4
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