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kernel/sysctl.c: detect overflows when converting to int

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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>
This commit is contained in:
Heinrich Schuchardt 2015-04-16 12:48:07 -07:00 committed by Linus Torvalds
parent 534b483a86
commit 230633d109
1 changed files with 9 additions and 1 deletions
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10
kernel/sysctl.c
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@ -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) {