[PATCH 1/9] bsd-user: Apply e6deac9cf99 from linux-user (zero anonymous memory)

[Warner Losh]

From: Mikaël Urankar <mikael.urankar@gmail.com>

linux-user/mmap.c: Always zero MAP_ANONYMOUS memory in mmap_frag()

When mapping MAP_ANONYMOUS memory fragments, still need notice about to
set it zero, or it will cause issues.

Signed-off-by: Chen Gang <gang.chen.5i5j@gmail.com>
Reviewed-by: Laurent Vivier <laurent@vivier.eu>
Signed-off-by: Riku Voipio <riku.voipio@linaro.org>
[ bsd-user merge by Mikaël Urankar, updated for untagged by Warner Losh ]
Signed-off-by: Mikaël Urankar <mikael.urankar@gmail.com>
Signed-off-by: Warner Losh <imp@bsdimp.com>
---
 bsd-user/mmap.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/bsd-user/mmap.c b/bsd-user/mmap.c
index b40ab9045f..fc3c1480f5 100644
--- a/bsd-user/mmap.c
+++ b/bsd-user/mmap.c
@@ -180,10 +180,12 @@ static int mmap_frag(abi_ulong real_start,
         if (prot_new != (prot1 | PROT_WRITE))
             mprotect(host_start, qemu_host_page_size, prot_new);
     } else {
-        /* just update the protection */
         if (prot_new != prot1) {
             mprotect(host_start, qemu_host_page_size, prot_new);
         }
+        if (prot_new & PROT_WRITE) {
+            memset(g2h_untagged(start), 0, end - start);
+        }
     }
     return 0;
 }
-- 
2.32.0