[34-longterm 107/209] sysctl: fix min/max handling in __do_proc_doulongvec_minmax()

From: Paul Gortmaker
Date: Thu Apr 14 2011 - 13:47:42 EST

From: Eric Dumazet <eric.dumazet@xxxxxxxxx>

| This is a commit scheduled for the next v2.6.34 longterm release. |
| If you see a problem with using this for longterm, please comment.|

commit 27b3d80a7b6adcf069b5e869e4efcc3a79f88a91 upstream.

When proc_doulongvec_minmax() is used with an array of longs, and no
min/max check requested (.extra1 or .extra2 being NULL), we dereference a
NULL pointer for the second element of the array.

Noticed while doing some changes in network stack for the "16TB problem"

Fix is to not change min & max pointers in __do_proc_doulongvec_minmax(),
so that all elements of the vector share an unique min/max limit, like

[akpm@xxxxxxxxxxxxxxxxxxxx: coding-style fixes]
Signed-off-by: Eric Dumazet <eric.dumazet@xxxxxxxxx>
Cc: "Eric W. Biederman" <ebiederm@xxxxxxxxxxxx>
Cc: Americo Wang <xiyou.wangcong@xxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Paul Gortmaker <paul.gortmaker@xxxxxxxxxxxxx>
kernel/sysctl.c | 2 +-
1 files changed, 1 insertions(+), 1 deletions(-)

diff --git a/kernel/sysctl.c b/kernel/sysctl.c
index 8686b0f..d2ceded 100644
--- a/kernel/sysctl.c
+++ b/kernel/sysctl.c
@@ -2314,7 +2314,7 @@ static int __do_proc_doulongvec_minmax(void *data, struct ctl_table *table, int
vleft = table->maxlen / sizeof(unsigned long);
left = *lenp;

- for (; left && vleft--; i++, min++, max++, first=0) {
+ for (; left && vleft--; i++, first = 0) {
if (write) {
while (left) {
char c;

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