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IB/rxe: do not copy extra stack memory to skb

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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 <keescook@chromium.org>
Cc: Moni Shoua <monis@mellanox.com>
Cc: Doug Ledford <dledford@redhat.com>
Cc: Sean Hefty <sean.hefty@intel.com>
Cc: Daniel Micay <danielmicay@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Kees Cook 2017-07-12 14:36:01 -07:00 committed by Linus Torvalds
parent e2ae8ab4b5
commit 4c93496f18
1 changed files with 3 additions and 1 deletions
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4
drivers/infiniband/sw/rxe/rxe_resp.c
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@ -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;