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[PATCH] avoid multiplication overflows and signedness issues for max_fds 

Limit sysctl_nr_open - we don't want ->max_fds to exceed MAX_INT and
we don't want size calculation for ->fd[] to overflow.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
This commit is contained in:
Al Viro 2008-05-10 10:08:32 -04:00
parent adbecb128c
commit eceea0b3df
2 changed files with 8 additions and 1 deletions
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4
fs/file.c
View File

@ -26,6 +26,8 @@ struct fdtable_defer {
};
int sysctl_nr_open __read_mostly = 1024*1024;
int sysctl_nr_open_min = BITS_PER_LONG;
int sysctl_nr_open_max = 1024 * 1024; /* raised later */
/*
* We use this list to defer free fdtables that have vmalloced
@ -405,6 +407,8 @@ void __init files_defer_init(void)
int i;
for_each_possible_cpu(i)
fdtable_defer_list_init(i);
sysctl_nr_open_max = min((size_t)INT_MAX, ~(size_t)0/sizeof(void *)) &
-BITS_PER_LONG;
}
struct files_struct init_files = {

5
kernel/sysctl.c
View File

@ -81,6 +81,7 @@ extern int compat_log;
extern int maps_protect;
extern int sysctl_stat_interval;
extern int latencytop_enabled;
extern int sysctl_nr_open_min, sysctl_nr_open_max;
/* Constants used for minimum and maximum */
#if defined(CONFIG_DETECT_SOFTLOCKUP) || defined(CONFIG_HIGHMEM)
@ -1190,7 +1191,9 @@ static struct ctl_table fs_table[] = {
.data = &sysctl_nr_open,
.maxlen = sizeof(int),
.mode = 0644,
.proc_handler = &proc_dointvec,
.proc_handler = &proc_dointvec_minmax,
.extra1 = &sysctl_nr_open_min,
.extra2 = &sysctl_nr_open_max,
},
{
.ctl_name = FS_DENTRY,