diff mbox series

[next] tipc: Use size_add() in calls to struct_size()

Message ID ZQStiorAZPgfMMZD@work
State New
Headers
Series [next] tipc: Use size_add() in calls to struct_size() |

Commit Message

Gustavo A. R. Silva Sept. 15, 2023, 7:16 p.m. UTC 
  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 <gustavoars@kernel.org>
---
 net/tipc/link.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

Comments

Kees Cook Sept. 15, 2023, 7:43 p.m. UTC | #1 
On Fri, Sep 15, 2023 at 01:16:26PM -0600, Gustavo A. R. Silva wrote:
> 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 <gustavoars@kernel.org>

Reviewed-by: Kees Cook <keescook@chromium.org>
diff mbox series

Patch

diff --git a/net/tipc/link.c b/net/tipc/link.c
index e33b4f29f77c..d0143823658d 100644
--- a/net/tipc/link.c
+++ b/net/tipc/link.c
@@ -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;
 }