From 16db3d3f1170fb0efca652c9378ce7c5f5cb4232 Mon Sep 17 00:00:00 2001 From: Heinrich Schuchardt Date: Thu, 16 Apr 2015 12:47:50 -0700 Subject: kernel/sysctl.c: threads-max observe limits Users can change the maximum number of threads by writing to /proc/sys/kernel/threads-max. With the patch the value entered is checked against the same limits that apply when fork_init is called. Signed-off-by: Heinrich Schuchardt Cc: Oleg Nesterov Cc: Ingo Molnar Cc: Guenter Roeck Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- kernel/sysctl.c | 6 ++---- 1 file changed, 2 insertions(+), 4 deletions(-) (limited to 'kernel/sysctl.c') diff --git a/kernel/sysctl.c b/kernel/sysctl.c index 42b7fc2860c1..3c0998426b57 100644 --- a/kernel/sysctl.c +++ b/kernel/sysctl.c @@ -93,11 +93,9 @@ #include #endif - #if defined(CONFIG_SYSCTL) /* External variables not in a header file. */ -extern int max_threads; extern int suid_dumpable; #ifdef CONFIG_COREDUMP extern int core_uses_pid; @@ -710,10 +708,10 @@ static struct ctl_table kern_table[] = { #endif { .procname = "threads-max", - .data = &max_threads, + .data = NULL, .maxlen = sizeof(int), .mode = 0644, - .proc_handler = proc_dointvec, + .proc_handler = sysctl_max_threads, }, { .procname = "random", -- cgit v1.2.3 From 230633d109e35b0a24277498e773edeb79b4a331 Mon Sep 17 00:00:00 2001 From: Heinrich Schuchardt Date: Thu, 16 Apr 2015 12:48:07 -0700 Subject: kernel/sysctl.c: detect overflows when converting to int When converting unsigned long to int overflows may occur. These currently are not detected when writing to the sysctl file system. E.g. on a system where int has 32 bits and long has 64 bits echo 0x800001234 > /proc/sys/kernel/threads-max has the same effect as echo 0x1234 > /proc/sys/kernel/threads-max The patch adds the missing check in do_proc_dointvec_conv. With the patch an overflow will result in an error EINVAL when writing to the the sysctl file system. Signed-off-by: Heinrich Schuchardt Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- kernel/sysctl.c | 10 +++++++++- 1 file changed, 9 insertions(+), 1 deletion(-) (limited to 'kernel/sysctl.c') diff --git a/kernel/sysctl.c b/kernel/sysctl.c index 3c0998426b57..2082b1a88fb9 100644 --- a/kernel/sysctl.c +++ b/kernel/sysctl.c @@ -1981,7 +1981,15 @@ static int do_proc_dointvec_conv(bool *negp, unsigned long *lvalp, int write, void *data) { if (write) { - *valp = *negp ? -*lvalp : *lvalp; + if (*negp) { + if (*lvalp > (unsigned long) INT_MAX + 1) + return -EINVAL; + *valp = -*lvalp; + } else { + if (*lvalp > (unsigned long) INT_MAX) + return -EINVAL; + *valp = *lvalp; + } } else { int val = *valp; if (val < 0) { -- cgit v1.2.3