Commit 230633d1 authored by Heinrich Schuchardt's avatar Heinrich Schuchardt Committed by Linus Torvalds

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: default avatarHeinrich Schuchardt <>
Signed-off-by: default avatarAndrew Morton <>
Signed-off-by: default avatarLinus Torvalds <>
parent 534b483a
......@@ -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) {
Markdown is supported
0% or .
You are about to add 0 people to the discussion. Proceed with caution.
Finish editing this message first!
Please register or to comment