From 4c93496f18ce5044d78e4f7f9e018682a4f44b3d Mon Sep 17 00:00:00 2001 From: Kees Cook Date: Wed, 12 Jul 2017 14:36:01 -0700 Subject: [PATCH] IB/rxe: do not copy extra stack memory to skb This fixes a over-read condition detected by FORTIFY_SOURCE for this line: memcpy(SKB_TO_PKT(skb), &ack_pkt, sizeof(skb->cb)); The error was: In file included from ./include/linux/bitmap.h:8:0, from ./include/linux/cpumask.h:11, from ./include/linux/mm_types_task.h:13, from ./include/linux/mm_types.h:4, from ./include/linux/kmemcheck.h:4, from ./include/linux/skbuff.h:18, from drivers/infiniband/sw/rxe/rxe_resp.c:34: In function 'memcpy', inlined from 'send_atomic_ack.constprop' at drivers/infiniband/sw/rxe/rxe_resp.c:998:2, inlined from 'acknowledge' at drivers/infiniband/sw/rxe/rxe_resp.c:1026:3, inlined from 'rxe_responder' at drivers/infiniband/sw/rxe/rxe_resp.c:1286:10: ./include/linux/string.h:309:4: error: call to '__read_overflow2' declared with attribute error: detected read beyond size of object passed as 2nd parameter __read_overflow2(); Daniel Micay noted that struct rxe_pkt_info is 32 bytes on 32-bit architectures, but skb->cb is still 64. The memcpy() over-reads 32 bytes. This fixes it by zeroing the unused bytes in skb->cb. Link: http://lkml.kernel.org/r/1497903987-21002-5-git-send-email-keescook@chromium.org Signed-off-by: Kees Cook Cc: Moni Shoua Cc: Doug Ledford Cc: Sean Hefty Cc: Daniel Micay Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- drivers/infiniband/sw/rxe/rxe_resp.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/drivers/infiniband/sw/rxe/rxe_resp.c b/drivers/infiniband/sw/rxe/rxe_resp.c index 2303976..be944d5 100644 --- a/drivers/infiniband/sw/rxe/rxe_resp.c +++ b/drivers/infiniband/sw/rxe/rxe_resp.c @@ -995,7 +995,9 @@ static int send_atomic_ack(struct rxe_qp *qp, struct rxe_pkt_info *pkt, free_rd_atomic_resource(qp, res); rxe_advance_resp_resource(qp); - memcpy(SKB_TO_PKT(skb), &ack_pkt, sizeof(skb->cb)); + memcpy(SKB_TO_PKT(skb), &ack_pkt, sizeof(ack_pkt)); + memset((unsigned char *)SKB_TO_PKT(skb) + sizeof(ack_pkt), 0, + sizeof(skb->cb) - sizeof(ack_pkt)); res->type = RXE_ATOMIC_MASK; res->atomic.skb = skb; -- 2.7.4