If one thread modifies the mappings and another thread prints them,
a situation may occur that the printer thread sees a guest mapping
without a corresponding host mapping, leading to a crash in
open_self_maps_2().
Cc: qemu-stable@nongnu.org
Fixes: 7b7a3366e142 ("linux-user: Use walk_memory_regions for open_self_maps")
Signed-off-by: Ilya Leoshkevich <iii@linux.ibm.com>
---
linux-user/syscall.c | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)
diff --git a/linux-user/syscall.c b/linux-user/syscall.c
index 1354e756941..dd2ec0712b8 100644
--- a/linux-user/syscall.c
+++ b/linux-user/syscall.c
@@ -8151,17 +8151,19 @@ static int open_self_maps_1(CPUArchState *env, int fd,
bool smaps)
{
struct open_self_maps_data d = {
.ts = get_task_state(env_cpu(env)),
- .host_maps = read_self_maps(),
.fd = fd,
.smaps = smaps
};
+ mmap_lock();
+ d.host_maps = read_self_maps();
if (d.host_maps) {
walk_memory_regions(&d, open_self_maps_2);
free_self_maps(d.host_maps);
} else {
walk_memory_regions(&d, open_self_maps_3);
}
+ mmap_unlock();
return 0;
}