[Xen-changelog] [xen master] x86: fix errors arising from c/s dab76ff

[patchbot@xxxxxxx]

commit fb0e5fea8acaf55d313a6eb6037c6549d0fc10af
Author:     Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
AuthorDate: Mon Feb 15 14:12:54 2016 +0100
Commit:     Jan Beulich <jbeulich@xxxxxxxx>
CommitDate: Mon Feb 15 14:12:54 2016 +0100

    x86: fix errors arising from c/s dab76ff
    
    Coverity correctly identifies that the changes in mtrr_attrib_to_str()
    introduce dead code.  strings[] is a 2d array, rather than an array of
    strings, which means that strings[x] will never be a NULL pointer.
    
    Adjust the check to compenstate, by looking for a NUL in strings[x][0]
    instead.
    
    Curiously, Coverity did not notice the same error with memory_type_to_str().
    There was also a further error; the strings were not NULL terminated, which
    made the return type of memory_type_to_str() erronious.
    
    Bump the 2D array to 3 characters, so the strings retain their NUL 
characters,
    and introduce an ASSERT() as requested on one thread of the original patch.
    
    Signed-off-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
---
 xen/arch/x86/cpu/mtrr/generic.c | 2 +-
 xen/arch/x86/mm/p2m-ept.c       | 5 +++--
 2 files changed, 4 insertions(+), 3 deletions(-)

diff --git a/xen/arch/x86/cpu/mtrr/generic.c b/xen/arch/x86/cpu/mtrr/generic.c
index 8839f8d..234d2ba 100644
--- a/xen/arch/x86/cpu/mtrr/generic.c
+++ b/xen/arch/x86/cpu/mtrr/generic.c
@@ -98,7 +98,7 @@ static const char *__init mtrr_attrib_to_str(mtrr_type x)
                [MTRR_TYPE_WRBACK]         = "write-back",
        };
 
-       return x < MTRR_NUM_TYPES ? (strings[x] ?: "?") : "?";
+       return (x < ARRAY_SIZE(strings) && strings[x][0]) ? strings[x] : "?";
 }
 
 static unsigned int __initdata last_fixed_start;
diff --git a/xen/arch/x86/mm/p2m-ept.c b/xen/arch/x86/mm/p2m-ept.c
index 316e3f3..3cb6868 100644
--- a/xen/arch/x86/mm/p2m-ept.c
+++ b/xen/arch/x86/mm/p2m-ept.c
@@ -1204,7 +1204,7 @@ void ept_p2m_uninit(struct p2m_domain *p2m)
 
 static const char *memory_type_to_str(unsigned int x)
 {
-    static const char memory_types[8][2] = {
+    static const char memory_types[8][3] = {
         [MTRR_TYPE_UNCACHABLE]     = "UC",
         [MTRR_TYPE_WRCOMB]         = "WC",
         [MTRR_TYPE_WRTHROUGH]      = "WT",
@@ -1213,7 +1213,8 @@ static const char *memory_type_to_str(unsigned int x)
         [MTRR_NUM_TYPES]           = "??"
     };
 
-    return x < ARRAY_SIZE(memory_types) ? (memory_types[x] ?: "?") : "?";
+    ASSERT(x < ARRAY_SIZE(memory_types));
+    return memory_types[x][0] ? memory_types[x] : "?";
 }
 
 static void ept_dump_p2m_table(unsigned char key)
--
generated by git-patchbot for /home/xen/git/xen.git#master

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