git: 64ee9c166ce5 - main - em(4): fix capability bounds needed to access checksum context.

The branch main has been updated by br:

URL: https://cgit.FreeBSD.org/src/commit/?id=64ee9c166ce5e807e575d205ac2e15cc5cf6581b

commit 64ee9c166ce5e807e575d205ac2e15cc5cf6581b
Author:     Ruslan Bukin <br@FreeBSD.org>
AuthorDate: 2025-11-25 09:16:39 +0000
Commit:     Ruslan Bukin <br@FreeBSD.org>
CommitDate: 2025-11-25 09:20:03 +0000

    em(4): fix capability bounds needed to access checksum context.
    
    Ensure the offp capability bounds cover entire struct with checksum fields.
    
    This is needed for CHERI systems to avoid bounds violation trap, as
    otherwise offp allowed to dereference 4 bytes of csum_flags field only
    so bzero failed.
    
    Tested on ARM Morello.
    
    Reviewed by:    kbowling
    Discussed with: jrtc27
    Sponsored by:   CHERI Research Centre
    Differential Revision:  https://reviews.freebsd.org/D53903
---
 sys/dev/e1000/if_em.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/sys/dev/e1000/if_em.c b/sys/dev/e1000/if_em.c
index bc841ba87ceb..7d7655a7ae6f 100644
--- a/sys/dev/e1000/if_em.c
+++ b/sys/dev/e1000/if_em.c
@@ -3638,7 +3638,7 @@ em_initialize_transmit_unit(if_ctx_t ctx)
 		bus_addr = txr->tx_paddr;
 
 		/* Clear checksum offload context. */
-		offp = (caddr_t)&txr->csum_flags;
+		offp = (caddr_t)txr + offsetof(struct tx_ring, csum_flags);
 		endp = (caddr_t)(txr + 1);
 		bzero(offp, endp - offp);