[PATCH] Range checking in do_proc_dointvec_(userhz_)jiffies_conv

When (integer) sysctl values are in either seconds or centiseconds, but
represented internally as jiffies, the allowable value range is decreased.
This patch adds range checks to the conversion routines.

For values in seconds: maximum LONG_MAX / HZ.

For values in centiseconds: maximum (LONG_MAX / HZ) * USER_HZ.

(BTW, does anyone else feel that an interface in seconds should not be
accepting negative values?)

Signed-off-by: Bart Samwel <bart@samwel.tk>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

diff --git a/kernel/sysctl.c b/kernel/sysctl.c
index d13426680d10128f7e01d452c8257eedb905fab8..e82726faeeffb4850cc49cc6e112cf28b143d4cb 100644 (file)
--- a/kernel/sysctl.c
+++ b/kernel/sysctl.c
@@ -2053,6 +2053,8 @@ static int do_proc_dointvec_jiffies_conv(int *negp, unsigned long *lvalp,
                                         int write, void *data)
 {
        if (write) {
+               if (*lvalp > LONG_MAX / HZ)
+                       return 1;
                *valp = *negp ? -(*lvalp*HZ) : (*lvalp*HZ);
        } else {
                int val = *valp;
@@ -2074,6 +2076,8 @@ static int do_proc_dointvec_userhz_jiffies_conv(int *negp, unsigned long *lvalp,
                                                int write, void *data)
 {
        if (write) {
+               if (USER_HZ < HZ && *lvalp > (LONG_MAX / HZ) * USER_HZ)
+                       return 1;
                *valp = clock_t_to_jiffies(*negp ? -*lvalp : *lvalp);
        } else {
                int val = *valp;