From: Volodymyr Babchuk <Volodymyr_Babchuk@epam.com>
To: Stefano Stabellini <sstabellini@kernel.org>,
Julien Grall <julien.grall@arm.com>
Cc: "xen-devel@lists.xenproject.org" <xen-devel@lists.xenproject.org>,
Volodymyr Babchuk <Volodymyr_Babchuk@epam.com>,
Stefano Stabellini <stefanos@xilinx.com>
Subject: [Xen-devel] [PATCH] xen/arm: optee: fix compilation with GCC 4.8
Date: Thu, 20 Jun 2019 15:50:21 +0000 [thread overview]
Message-ID: <20190620154952.31286-1-volodymyr_babchuk@epam.com> (raw)
GCC 4.8 is unable to see that variables guest_pg, guest_data and
xen_data will be always initialized before access, so we need to
initialize them earlier.
Suggested-by: Stefano Stabellini <stefanos@xilinx.com>
Signed-off-by: Volodymyr Babchuk <volodymyr_babchuk@epam.com>
---
xen/arch/arm/tee/optee.c | 13 +++++++++++++
1 file changed, 13 insertions(+)
diff --git a/xen/arch/arm/tee/optee.c b/xen/arch/arm/tee/optee.c
index 14381d6b2d..5526875e6f 100644
--- a/xen/arch/arm/tee/optee.c
+++ b/xen/arch/arm/tee/optee.c
@@ -717,6 +717,19 @@ static int translate_noncontig(struct optee_domain *ctx,
gfn = gaddr_to_gfn(param->u.tmem.buf_ptr &
~(OPTEE_MSG_NONCONTIG_PAGE_SIZE - 1));
+ /*
+ * We are initializing guest_pg, guest_data and xen_data with NULL
+ * to make GCC 4.8 happy, as it can't infer that those variables
+ * will be initialized with correct values in the loop below.
+ *
+ * This silences old GCC, but can lead to NULL dereference, in
+ * case of programmer's mistake. To minimize chance of this, we
+ * are initializing those variables there, instead of doing this
+ * at beginning of the function.
+ */
+ guest_pg = NULL;
+ xen_data = NULL;
+ guest_data = NULL;
while ( pg_count )
{
struct page_info *page;
--
2.21.0
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next reply other threads:[~2019-06-20 15:50 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-06-20 15:50 Volodymyr Babchuk [this message]
2019-06-21 0:28 ` [Xen-devel] [PATCH] xen/arm: optee: fix compilation with GCC 4.8 Stefano Stabellini
2019-06-21 9:33 ` Julien Grall
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