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Subject[PATCH 3.8 112/152] ipc: tighten msg copy loops
Date
3.8.13.14 -stable review patch.  If anyone has any objections, please let me know.

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

From: Peter Hurley <peter@hurleysoftware.com>

commit da085d4591a6fe11eac2e1f659f25b655e9f2e53 upstream.

Signed-off-by: Peter Hurley <peter@hurleysoftware.com>
Acked-by: Stanislav Kinsbursky <skinsbursky@parallels.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
[ kamal: 3.8 stable prereq for
4e9b45a ipc, msg: fix message length check for negative values ]
Signed-off-by: Kamal Mostafa <kamal@canonical.com>
---
ipc/msgutil.c | 32 +++++++++++---------------------
1 file changed, 11 insertions(+), 21 deletions(-)

diff --git a/ipc/msgutil.c b/ipc/msgutil.c
index 0a5c8a9..b79582d 100644
--- a/ipc/msgutil.c
+++ b/ipc/msgutil.c
@@ -97,18 +97,14 @@ struct msg_msg *load_msg(const void __user *src, int len)
goto out_err;
}

- len -= alen;
- src = ((char __user *)src) + alen;
- seg = msg->next;
- while (len > 0) {
+ for (seg = msg->next; seg != NULL; seg = seg->next) {
+ len -= alen;
+ src = (char __user *)src + alen;
alen = min(len, DATALEN_SEG);
if (copy_from_user(seg + 1, src, alen)) {
err = -EFAULT;
goto out_err;
}
- seg = seg->next;
- len -= alen;
- src = ((char __user *)src) + alen;
}

err = security_msg_msg_alloc(msg);
@@ -135,15 +131,13 @@ struct msg_msg *copy_msg(struct msg_msg *src, struct msg_msg *dst)
alen = min(len, DATALEN_MSG);
memcpy(dst + 1, src + 1, alen);

- len -= alen;
- dst_pseg = dst->next;
- src_pseg = src->next;
- while (len > 0) {
+ for (dst_pseg = dst->next, src_pseg = src->next;
+ src_pseg != NULL;
+ dst_pseg = dst_pseg->next, src_pseg = src_pseg->next) {
+
+ len -= alen;
alen = min(len, DATALEN_SEG);
memcpy(dst_pseg + 1, src_pseg + 1, alen);
- dst_pseg = dst_pseg->next;
- len -= alen;
- src_pseg = src_pseg->next;
}

dst->m_type = src->m_type;
@@ -166,16 +160,12 @@ int store_msg(void __user *dest, struct msg_msg *msg, int len)
if (copy_to_user(dest, msg + 1, alen))
return -1;

- len -= alen;
- dest = ((char __user *)dest) + alen;
- seg = msg->next;
- while (len > 0) {
+ for (seg = msg->next; seg != NULL; seg = seg->next) {
+ len -= alen;
+ dest = (char __user *)dest + alen;
alen = min(len, DATALEN_SEG);
if (copy_to_user(dest, seg + 1, alen))
return -1;
- len -= alen;
- dest = ((char __user *)dest) + alen;
- seg = seg->next;
}
return 0;
}
--
1.8.3.2


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