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From: Sean Christopherson <sean.j.christopherson@intel.com>
To: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
Cc: linux-sgx@vger.kernel.org
Subject: [PATCH for_v23 1/5] x86/vdso: sgx: Fix misaligned stack bug when invoking exit handler
Date: Thu, 10 Oct 2019 17:40:55 -0700
Message-ID: <20191011004059.28581-2-sean.j.christopherson@intel.com> (raw)
In-Reply-To: <20191011004059.28581-1-sean.j.christopherson@intel.com>

Fix a recently introduced bug where an odd number of 8-byte parameters
are pushed on the stack prior to invoking the userspace callback, which
causes the CALL to execute with an unaligned stack and violate the
x86_64 ABI.

Reported-by: Cedric Xing <cedric.xing@intel.com>
Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
---
 arch/x86/entry/vdso/vsgx_enter_enclave.S | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/arch/x86/entry/vdso/vsgx_enter_enclave.S b/arch/x86/entry/vdso/vsgx_enter_enclave.S
index fc5622dcd2fa..b63091818df1 100644
--- a/arch/x86/entry/vdso/vsgx_enter_enclave.S
+++ b/arch/x86/entry/vdso/vsgx_enter_enclave.S
@@ -135,10 +135,12 @@ ENTRY(__vdso_sgx_enter_enclave)
 .Linvoke_userspace_handler:
 	/*
 	 * Align stack per x86_64 ABI. Save the original %rsp in %rbx to be
-	 * restored after the callback returns.
+	 * restored after the callback returns.  Note, %rsp needs to be 16-byte
+	 * aligned _after_ pushing the three parameters on the stack.
 	 */
 	mov	%rsp, %rbx
 	and	$-0x10, %rsp
+	sub	$0x8, %rsp
 
 	/* Push @e, u_rsp and @tcs as parameters to the callback. */
 	push	0x18(%rbp)
-- 
2.22.0


  reply index

Thread overview: 12+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-10-11  0:40 [PATCH for_v23 0/5] x86/vdso: sgx: Bug fixes Sean Christopherson
2019-10-11  0:40 ` Sean Christopherson [this message]
2019-10-11  0:40 ` [PATCH for_v23 2/5] selftests/x86/sgx: Add check to verify exit handler stack alignment Sean Christopherson
2019-10-14 21:09   ` Jarkko Sakkinen
2019-10-14 21:14     ` Jarkko Sakkinen
2019-10-11  0:40 ` [PATCH for_v23 3/5] x86/vdso: sgx: Fix unwinder support Sean Christopherson
2019-10-16 22:25   ` Xing, Cedric
2019-10-11  0:40 ` [PATCH for_v23 4/5] x86/vdso: sgx: Reorder params to callback to improve readability Sean Christopherson
2019-10-16 22:24   ` Xing, Cedric
2019-10-16 23:06     ` Sean Christopherson
2019-10-11  0:40 ` [PATCH for_v23 5/5] selftests/x86/sgx: Update the callbacks function parameters Sean Christopherson
2019-10-14 21:27 ` [PATCH for_v23 0/5] x86/vdso: sgx: Bug fixes Jarkko Sakkinen

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