From: Heinrich Schuchardt <xypron.glpk@gmx.de>
Date: Thu, 16 Apr 2015 19:48:07 +0000 (-0700)
Subject: kernel/sysctl.c: detect overflows when converting to int
X-Git-Url: https://git.stricted.de/?a=commitdiff_plain;h=230633d109e35b0a24277498e773edeb79b4a331;p=GitHub%2Fexynos8895%2Fandroid_kernel_samsung_universal8895.git

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 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) {