[PATCH 3.8 110/152] ipc: clamp with min()

From: Kamal Mostafa
Date: Fri Dec 06 2013 - 18:28:49 EST


3.8.13.14 -stable review patch. If anyone has any objections, please let me know.

------------------

From: Peter Hurley <peter@xxxxxxxxxxxxxxxxxx>

commit 3d8fa456d5ed22ce8db085a89a037b87568b2b64 upstream.

Signed-off-by: Peter Hurley <peter@xxxxxxxxxxxxxxxxxx>
Acked-by: Stanislav Kinsbursky <skinsbursky@xxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
[ kamal: 3.8 stable prereq for
4e9b45a ipc, msg: fix message length check for negative values ]
Signed-off-by: Kamal Mostafa <kamal@xxxxxxxxxxxxx>
---
ipc/msgutil.c | 30 ++++++++----------------------
1 file changed, 8 insertions(+), 22 deletions(-)

diff --git a/ipc/msgutil.c b/ipc/msgutil.c
index 5df8e4b..98b1c2b 100644
--- a/ipc/msgutil.c
+++ b/ipc/msgutil.c
@@ -41,8 +41,8 @@ struct msg_msgseg {
/* the next part of the message follows immediately */
};

-#define DATALEN_MSG (PAGE_SIZE-sizeof(struct msg_msg))
-#define DATALEN_SEG (PAGE_SIZE-sizeof(struct msg_msgseg))
+#define DATALEN_MSG (int)(PAGE_SIZE-sizeof(struct msg_msg))
+#define DATALEN_SEG (int)(PAGE_SIZE-sizeof(struct msg_msgseg))

struct msg_msg *load_msg(const void __user *src, int len)
{
@@ -51,10 +51,7 @@ struct msg_msg *load_msg(const void __user *src, int len)
int err;
int alen;

- alen = len;
- if (alen > DATALEN_MSG)
- alen = DATALEN_MSG;
-
+ alen = min(len, DATALEN_MSG);
msg = kmalloc(sizeof(*msg) + alen, GFP_KERNEL);
if (msg == NULL)
return ERR_PTR(-ENOMEM);
@@ -72,9 +69,7 @@ struct msg_msg *load_msg(const void __user *src, int len)
pseg = &msg->next;
while (len > 0) {
struct msg_msgseg *seg;
- alen = len;
- if (alen > DATALEN_SEG)
- alen = DATALEN_SEG;
+ alen = min(len, DATALEN_SEG);
seg = kmalloc(sizeof(*seg) + alen,
GFP_KERNEL);
if (seg == NULL) {
@@ -113,19 +108,14 @@ struct msg_msg *copy_msg(struct msg_msg *src, struct msg_msg *dst)
if (src->m_ts > dst->m_ts)
return ERR_PTR(-EINVAL);

- alen = len;
- if (alen > DATALEN_MSG)
- alen = DATALEN_MSG;
-
+ alen = min(len, DATALEN_MSG);
memcpy(dst + 1, src + 1, alen);

len -= alen;
dst_pseg = dst->next;
src_pseg = src->next;
while (len > 0) {
- alen = len;
- if (alen > DATALEN_SEG)
- alen = DATALEN_SEG;
+ alen = min(len, DATALEN_SEG);
memcpy(dst_pseg + 1, src_pseg + 1, alen);
dst_pseg = dst_pseg->next;
len -= alen;
@@ -148,9 +138,7 @@ int store_msg(void __user *dest, struct msg_msg *msg, int len)
int alen;
struct msg_msgseg *seg;

- alen = len;
- if (alen > DATALEN_MSG)
- alen = DATALEN_MSG;
+ alen = min(len, DATALEN_MSG);
if (copy_to_user(dest, msg + 1, alen))
return -1;

@@ -158,9 +146,7 @@ int store_msg(void __user *dest, struct msg_msg *msg, int len)
dest = ((char __user *)dest) + alen;
seg = msg->next;
while (len > 0) {
- alen = len;
- if (alen > DATALEN_SEG)
- alen = DATALEN_SEG;
+ alen = min(len, DATALEN_SEG);
if (copy_to_user(dest, seg + 1, alen))
return -1;
len -= alen;
--
1.8.3.2

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