[Xen-changelog] [xen master] x86/traps: Fix failed ASSERT() in do_guest_trap()

[patchbot@xxxxxxx]

commit 6480cc6280e955d1245d8dfb2456d2b830240c74
Author:     Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
AuthorDate: Wed Aug 10 10:41:28 2016 +0100
Commit:     Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
CommitDate: Wed Aug 10 12:44:02 2016 +0100

    x86/traps: Fix failed ASSERT() in do_guest_trap()
    
    c/s 2e426d6 "x86/traps: Drop use_error_code parameter from 
do_{,guest_}trap()"
    introduced an assertion which covered the correctness of shifting 1u by an
    input parameter.
    
    While all other inputs provide a constants vector, the `int $N` handling 
path
    from do_general_protection() passes any vector.
    
    This path is triggered by XTF, which uses `int 0x20` to facilitate returning
    to kernel mode after running specific tests in user mode.
    
    No vectors above 32 have an error code, so adjust the logic to cope.
    
    Reported-by: Wei Liu <wei.liu2@xxxxxxxxxx>
    Signed-off-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
    Reviewed-by: Jan Beulich <jbeulich@xxxxxxxx>
---
 xen/arch/x86/traps.c | 7 ++-----
 1 file changed, 2 insertions(+), 5 deletions(-)

diff --git a/xen/arch/x86/traps.c b/xen/arch/x86/traps.c
index c228b45..e822719 100644
--- a/xen/arch/x86/traps.c
+++ b/xen/arch/x86/traps.c
@@ -631,11 +631,8 @@ static void do_guest_trap(unsigned int trapnr,
     struct vcpu *v = current;
     struct trap_bounce *tb;
     const struct trap_info *ti;
-    bool_t use_error_code;
-
-    ASSERT(trapnr < 32);
-
-    use_error_code = (TRAP_HAVE_EC & (1u << trapnr));
+    const bool use_error_code =
+        ((trapnr < 32) && (TRAP_HAVE_EC & (1u << trapnr)));
 
     trace_pv_trap(trapnr, regs->eip, use_error_code, regs->error_code);
 
--
generated by git-patchbot for /home/xen/git/xen.git#master

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