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| author | Matthew Daley <mattjd@gmail.com> | 2013-10-10 15:19:53 +0200 |
|---|---|---|
| committer | Jan Beulich <jbeulich@suse.com> | 2013-10-10 15:19:53 +0200 |
| commit | 0771faba163769089c9f05f7f76b63e397677613 (patch) | |
| tree | 07432c02810cdbc5934bc3c3d6c701f882899255 | |
| parent | e9ee35826e46e4f9a40f9fdafcc609016cb2a23b (diff) | |
| download | xen-0771faba163769089c9f05f7f76b63e397677613.tar.gz xen-0771faba163769089c9f05f7f76b63e397677613.tar.bz2 xen-0771faba163769089c9f05f7f76b63e397677613.zip | |
x86: check segment descriptor read result in 64-bit OUTS emulation
When emulating such an operation from a 64-bit context (CS has long
mode set), and the data segment is overridden to FS/GS, the result of
reading the overridden segment's descriptor (read_descriptor) is not
checked. If it fails, data_base is left uninitialized.
This can lead to 8 bytes of Xen's stack being leaked to the guest
(implicitly, i.e. via the address given in a #PF).
Coverity-ID: 1055116
This is CVE-2013-4368 / XSA-67.
Signed-off-by: Matthew Daley <mattjd@gmail.com>
Fix formatting.
Signed-off-by: Jan Beulich <jbeulich@suse.com>
| -rw-r--r-- | xen/arch/x86/traps.c | 8 |
1 files changed, 4 insertions, 4 deletions
diff --git a/xen/arch/x86/traps.c b/xen/arch/x86/traps.c index 47c71b7689..4a0950280f 100644 --- a/xen/arch/x86/traps.c +++ b/xen/arch/x86/traps.c @@ -1986,10 +1986,10 @@ static int emulate_privileged_op(struct cpu_user_regs *regs) break; } } - else - read_descriptor(data_sel, v, regs, - &data_base, &data_limit, &ar, - 0); + else if ( !read_descriptor(data_sel, v, regs, + &data_base, &data_limit, &ar, 0) || + !(ar & _SEGMENT_S) || !(ar & _SEGMENT_P) ) + goto fail; data_limit = ~0UL; ar = _SEGMENT_WR|_SEGMENT_S|_SEGMENT_DPL|_SEGMENT_P; } |