LU-16509 lnet: quash memcpy WARN_ONCE false positive

Linux v6.1-rc1-4-g6f7630b1b5bc
  fortify: Capture __bos() results in const temp var

In lnet_peer_push_event() the memcpy triggers a WARN_ONCE
due to the flexible array at the end of
struct lnet_ping_info contained in struct lnet_ping_buffer

Use unsafe_memcpy() to avoid this false positive warning.

Lustre-change: https://review.whamcloud.com/49801
Lustre-commit: a3cf8587b6fafdfed16fe0870efddcf6c0746c88

Test-Parameters: trivial
Signed-off-by: Shaun Tancheff <shaun.tancheff@hpe.com>
Change-Id: I4aa8f38678cd1522004d98b58a3f440d8a38589c
Signed-off-by: Stephane Thiell <sthiell@stanford.edu>
Reviewed-on: https://review.whamcloud.com/c/fs/lustre-release/+/50647
Tested-by: jenkins <devops@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: Jian Yu <yujian@whamcloud.com>
Reviewed-by: Oleg Drokin <green@whamcloud.com>

diff --git a/libcfs/include/libcfs/libcfs.h b/libcfs/include/libcfs/libcfs.h
index 11bbaaa..79ba608 100644 (file)
--- a/libcfs/include/libcfs/libcfs.h
+++ b/libcfs/include/libcfs/libcfs.h
@@ -132,4 +132,12 @@ void libcfs_vfree_atomic(const void *addr);
 #define INTERVAL_TREE_ROOT RB_ROOT
 #endif /* HAVE_INTERVAL_TREE_CACHED */
 
+#ifndef unsafe_memcpy
+#define unsafe_memcpy(to, from, size, reason)  memcpy((to), (from), (size))
+#endif
+
+#define FLEXIBLE_OBJECT \
+       "Struct contains a flexible member, the size of object is checked" \
+       "and can be safely copied in a single memcpy()"
+
 #endif /* _LIBCFS_LIBCFS_H_ */

diff --git a/lnet/include/uapi/linux/lnet/lnet-idl.h b/lnet/include/uapi/linux/lnet/lnet-idl.h
index 7ed58a3..bdff24e 100644 (file)
--- a/lnet/include/uapi/linux/lnet/lnet-idl.h
+++ b/lnet/include/uapi/linux/lnet/lnet-idl.h
@@ -287,7 +287,7 @@ struct lnet_ping_info {
        __u32                   pi_features;
        lnet_pid_t              pi_pid;
        __u32                   pi_nnis;
-       struct lnet_ni_status   pi_ni[0];
+       struct lnet_ni_status   pi_ni[];
 } __attribute__((packed));
 
 #define LNET_PING_INFO_SIZE(NNIDS) \

diff --git a/lnet/lnet/api-ni.c b/lnet/lnet/api-ni.c
index 76cac6e..b99c85b 100644 (file)
--- a/lnet/lnet/api-ni.c
+++ b/lnet/lnet/api-ni.c
@@ -870,7 +870,7 @@ static void lnet_assert_wire_constants(void)
        BUILD_BUG_ON((int)offsetof(struct lnet_ping_info, pi_nnis) != 12);
        BUILD_BUG_ON((int)sizeof(((struct lnet_ping_info *)0)->pi_nnis) != 4);
        BUILD_BUG_ON((int)offsetof(struct lnet_ping_info, pi_ni) != 16);
-       BUILD_BUG_ON((int)sizeof(((struct lnet_ping_info *)0)->pi_ni) != 0);
+       BUILD_BUG_ON(offsetof(struct lnet_ping_info, pi_ni) != sizeof(struct lnet_ping_info));
 
        /* Acceptor connection request */
        BUILD_BUG_ON(LNET_PROTO_ACCEPTOR_VERSION != 1);

diff --git a/lnet/lnet/peer.c b/lnet/lnet/peer.c
index df3c9b9..7a438ea 100644 (file)
--- a/lnet/lnet/peer.c
+++ b/lnet/lnet/peer.c
@@ -2515,8 +2515,8 @@ void lnet_peer_push_event(struct lnet_event *ev)
        }
 
        /* Success */
-       memcpy(&lp->lp_data->pb_info, &pbuf->pb_info,
-              LNET_PING_INFO_SIZE(pbuf->pb_info.pi_nnis));
+       unsafe_memcpy(&lp->lp_data->pb_info, &pbuf->pb_info,
+              LNET_PING_INFO_SIZE(pbuf->pb_info.pi_nnis), FLEXIBLE_OBJECT);
        lp->lp_state |= LNET_PEER_DATA_PRESENT;
        CDEBUG(D_NET, "Received Push %s %u\n",
               libcfs_nidstr(&lp->lp_primary_nid),

diff --git a/lnet/utils/wirecheck.c b/lnet/utils/wirecheck.c
index 2a23e74..3985104 100644 (file)
--- a/lnet/utils/wirecheck.c
+++ b/lnet/utils/wirecheck.c
@@ -58,6 +58,9 @@ do {                                            \
 
 #define STRINGIFY(a) #a
 
+#define CHECK_BUILD_TEST(a)                                    \
+       printf("        BUILD_BUG_ON("#a");\n")
+
 #define CHECK_DEFINE(a)                                                 \
 do {                                                                    \
         printf ("        BUILD_BUG_ON("#a" != "STRINGIFY(a)");\n");     \
@@ -78,6 +81,12 @@ do {                                            \
         CHECK_VALUE((int)sizeof(((s *)0)->m));  \
 } while (0)
 
+#define CHECK_MEMBER_IS_FLEXIBLE(s, m)                 \
+do {                                                                   \
+       CHECK_MEMBER_OFFSET(s, m);                                      \
+       CHECK_BUILD_TEST(offsetof(struct s, m) != sizeof(struct s));    \
+} while (0)
+
 #define CHECK_MEMBER(s,m)                       \
 do {                                            \
         CHECK_MEMBER_OFFSET(s, m);              \
@@ -188,7 +197,7 @@ check_lnet_ping_info(void)
        CHECK_MEMBER(struct lnet_ping_info, pi_features);
        CHECK_MEMBER(struct lnet_ping_info, pi_pid);
        CHECK_MEMBER(struct lnet_ping_info, pi_nnis);
-       CHECK_MEMBER(struct lnet_ping_info, pi_ni);
+       CHECK_MEMBER_IS_FLEXIBLE(struct lnet_ping_info, pi_ni);
 }
 
 void

diff --git a/lustre/utils/wirecheck.c b/lustre/utils/wirecheck.c
index d08cce0..b62cbff 100644 (file)
--- a/lustre/utils/wirecheck.c
+++ b/lustre/utils/wirecheck.c
@@ -142,6 +142,12 @@ do {                                                               \
        CHECK_VALUE((int)sizeof(((s *)0)->m));                  \
 } while(0)
 
+#define CHECK_MEMBER_IS_FLEXIBLE(s, m)                 \
+do {                                                                   \
+       CHECK_MEMBER_OFFSET(s, m);                                      \
+       CHECK_BUILD_TEST(offsetof(struct s, m) != sizeof(struct s));    \
+} while (0)
+
 #define CHECK_MEMBER(s, m)                                     \
 do {                                                           \
        CHECK_MEMBER_OFFSET(s, m);                              \
@@ -2222,7 +2228,7 @@ check_ll_user_fiemap(void)
        CHECK_MEMBER(fiemap, fm_mapped_extents);
        CHECK_MEMBER(fiemap, fm_extent_count);
        CHECK_MEMBER(fiemap, fm_reserved);
-       CHECK_MEMBER(fiemap, fm_extents);
+       CHECK_MEMBER_IS_FLEXIBLE(fiemap, fm_extents);
 
        CHECK_CDEFINE(FIEMAP_FLAG_SYNC);
        CHECK_CDEFINE(FIEMAP_FLAG_XATTR);