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tipc: Use size_add() in calls to struct_size()

PATCH In review Gustavo A. R. Silva 2 participants 2 messages Sep 15, 2023

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Networking Network drivers TIPC network layer
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Gustavo A. R. Silva

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#0 lore raw

PATCH 1/1 tipc: Use size_add() in calls to struct_size()

If, for any reason, the open-coded arithmetic causes a wraparound, the protection that struct_size() adds against potential integer overflows is defeated. Fix this by hardening call to struct_size() with size_add().

Fixes e034c6d23bc4 ("tipc: Use struct_size() helper")
Signed-off-by Gustavo A. R. Silva <[email protected]>
---
 net/tipc/link.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)
net/tipc/link.c +2 -2
index e33b4f29f77c..d0143823658d 100644
@@ -1446,7 +1446,7 @@ u16 tipc_get_gap_ack_blks(struct tipc_gap_ack_blks **ga, struct tipc_link *l,
 		p = (struct tipc_gap_ack_blks *)msg_data(hdr);
 		sz = ntohs(p->len);
 		/* Sanity check */
-		if (sz == struct_size(p, gacks, p->ugack_cnt + p->bgack_cnt)) {
+		if (sz == struct_size(p, gacks, size_add(p->ugack_cnt, p->bgack_cnt))) {
 			/* Good, check if the desired type exists */
 			if ((uc && p->ugack_cnt) || (!uc && p->bgack_cnt))
 				goto ok;

@@ -1533,7 +1533,7 @@ static u16 tipc_build_gap_ack_blks(struct tipc_link *l, struct tipc_msg *hdr)
 			__tipc_build_gap_ack_blks(ga, l, ga->bgack_cnt) : 0;
 
 	/* Total len */
-	len = struct_size(ga, gacks, ga->bgack_cnt + ga->ugack_cnt);
+	len = struct_size(ga, gacks, size_add(ga->bgack_cnt, ga->ugack_cnt));
 	ga->len = htons(len);
 	return len;
 }
Signature · 1 line
2.34.1
Reviewed-by on v1 1/1
#1 lore raw
Quoted 7 lines · Gustavo A. R. Silva

If, for any reason, the open-coded arithmetic causes a wraparound, the protection that struct_size() adds against potential integer overflows is defeated. Fix this by hardening call to struct_size() with size_add().

Fixes e034c6d23bc4 ("tipc: Use struct_size() helper")
Signed-off-by Gustavo A. R. Silva <[email protected]>
Reviewed-by Kees Cook <[email protected]>
Signature · 1 line
Kees Cook