[PATCH v2 5.4 regression fix] x86/boot: Provide memzero_explicit

Hans de Goede
2019-10-07T13:47:24Z

The purgatory code now uses the shared lib/crypto/sha256.c sha256
implementation. This needs memzero_explicit, implement this.

Reported-by: Arvind Sankar <nivedita@alum.mit.edu>
Fixes: 906a4bb97f5d ("crypto: sha256 - Use get/put_unaligned_be32 to get input, memzero_explicit")
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
---
Changes in v2:
- Add barrier_data() call after the memset, making the function really
explicit. Using barrier_data() works fine in the purgatory (build)
environment.
---
arch/x86/boot/compressed/string.c | 6 ++++++
1 file changed, 6 insertions(+)

diff --git a/arch/x86/boot/compressed/string.c b/arch/x86/boot/compressed/string.c
index 81fc1eaa3229..654a7164a702 100644
--- a/arch/x86/boot/compressed/string.c
+++ b/arch/x86/boot/compressed/string.c
@@ -50,6 +50,12 @@ void *memset(void *s, int c, size_t n)
return s;
}

+void memzero_explicit(void *s, size_t count)
+{
+ memset(s, 0, count);
+ barrier_data(s);
+}
+
void *memmove(void *dest, const void *src, size_t n)
{
unsigned char *d = dest;
--
2.23.0