[PATCH v5 03/16] livepatch: Reject payloads with .alternative or .ex_table if support is not built-in.

From: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
To: konrad@kernel.org, xen-devel@lists.xenproject.org,
	ross.lagerwall@citrix.com, sstabellini@kernel.org,
	julien.grall@arm.com
Cc: Andrew Cooper <andrew.cooper3@citrix.com>,
	Jan Beulich <jbeulich@suse.com>,
	Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Subject: [PATCH v5 03/16] livepatch: Reject payloads with .alternative or .ex_table if support is not built-in.
Date: Wed, 21 Sep 2016 13:32:21 -0400	[thread overview]
Message-ID: <1474479154-20991-4-git-send-email-konrad.wilk@oracle.com> (raw)
In-Reply-To: <1474479154-20991-1-git-send-email-konrad.wilk@oracle.com>

If the payload had the sections mentioned but the hypervisor
did not support some of them (say on ARM the .ex_table) - instead
of ignoring them - it should forbid loading of such payload.

Reviewed-by: Julien Grall <julien.grall@arm.com>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
---
Cc: Stefano Stabellini <sstabellini@kernel.org>
Cc: Julien Grall <julien.grall@arm.com>
Cc: Jan Beulich <jbeulich@suse.com>
Cc: Andrew Cooper <andrew.cooper3@citrix.com>

v3: New submission.
v4: Added Julien's Reviewed-by tag.
---
 xen/common/livepatch.c | 16 ++++++++++++----
 1 file changed, 12 insertions(+), 4 deletions(-)

diff --git a/xen/common/livepatch.c b/xen/common/livepatch.c
index 292dd2e..66f23e0 100644
--- a/xen/common/livepatch.c
+++ b/xen/common/livepatch.c
@@ -643,10 +643,10 @@ static int prepare_payload(struct payload *payload,
                                   sizeof(*region->frame[i].bugs);
     }
 
-#ifdef CONFIG_HAS_ALTERNATIVE
     sec = livepatch_elf_sec_by_name(elf, ".altinstructions");
     if ( sec )
     {
+#ifdef CONFIG_HAS_ALTERNATIVE
         struct alt_instr *a, *start, *end;
 
         if ( sec->sec->sh_size % sizeof(*a) )
@@ -673,13 +673,17 @@ static int prepare_payload(struct payload *payload,
             }
         }
         apply_alternatives(start, end);
-    }
+#else
+        dprintk(XENLOG_ERR, LIVEPATCH "%s: We don't support alternative patching!\n",
+                elf->name);
+        return -EOPNOTSUPP;
 #endif
+    }
 
-#ifdef CONFIG_HAS_EX_TABLE
     sec = livepatch_elf_sec_by_name(elf, ".ex_table");
     if ( sec )
     {
+#ifdef CONFIG_HAS_EX_TABLE
         struct exception_table_entry *s, *e;
 
         if ( !sec->sec->sh_size ||
@@ -698,8 +702,12 @@ static int prepare_payload(struct payload *payload,
 
         region->ex = s;
         region->ex_end = e;
-    }
+#else
+        dprintk(XENLOG_ERR, LIVEPATCH "%s: We don't support .ex_table!\n",
+                elf->name);
+        return -EOPNOTSUPP;
 #endif
+    }
 
     return 0;
 }
-- 
2.4.11


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