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 <xypron.glpk@gmx.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/kernel/sysctl.c b/kernel/sysctl.c
index 3c09984..2082b1a 100644
--- a/kernel/sysctl.c
+++ b/kernel/sysctl.c
@@ -1981,7 +1981,15 @@
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) {