[CRIU] [PATCH] restore: Compute auxv size taking into account kernel's mm::saved_auxv type

[Cyrill Gorcunov]

On 32-bit ARM machine we've got:

 | 10:45:28.595:  4927: new environ: GIT_URL=git://git.criu.org/crtools.git
 | 10:45:28.595:  4927: FAIL: cmdlinenv00.c:116: auxv corrupted on restore (errno = 11 (Resource temporarily unavailable))

that's because in commit 459828b6bec92d664bcce8419436e528be2094f2
we've changed reading procedure of auxv but forgot to update
restore procedure (which were thinking that size of vector
remains in number of "passes".

Fix it computing proper number of bytes need to be passed into
kernel prctl call, same time it allows us to copy auxv to
needed destination in one memcpy call.

Reported-by: Andrey Vagin <avagin at openvz.org>
Signed-off-by: Cyrill Gorcunov <gorcunov at openvz.org>
---
 cr-restore.c | 13 +++++++------
 1 file changed, 7 insertions(+), 6 deletions(-)

diff --git a/cr-restore.c b/cr-restore.c
index 22614dba1207..792f08eb6448 100644
--- a/cr-restore.c
+++ b/cr-restore.c
@@ -1920,22 +1920,23 @@ static int prepare_creds(int pid, struct task_restore_args *args)
 
 static int prepare_mm(pid_t pid, struct task_restore_args *args)
 {
-	int exe_fd, i, ret = -1;
+	int exe_fd, ret = -1;
 	MmEntry *mm = current->rst->mm;
+	size_t size;
 
 	args->mm = *mm;
 	args->mm.n_mm_saved_auxv = 0;
 	args->mm.mm_saved_auxv = NULL;
 
-	if (mm->n_mm_saved_auxv > AT_VECTOR_SIZE) {
+	size = mm->n_mm_saved_auxv * sizeof(mm->mm_saved_auxv[0]);
+
+	if (size / sizeof(long) > AT_VECTOR_SIZE) {
 		pr_err("Image corrupted on pid %d\n", pid);
 		goto out;
 	}
 
-	args->mm_saved_auxv_size = mm->n_mm_saved_auxv*sizeof(auxv_t);
-	for (i = 0; i < mm->n_mm_saved_auxv; ++i) {
-		args->mm_saved_auxv[i] = (auxv_t)mm->mm_saved_auxv[i];
-	}
+	args->mm_saved_auxv_size = size;
+	memcpy(args->mm_saved_auxv, mm->mm_saved_auxv, size);
 
 	exe_fd = open_reg_by_id(mm->exe_file_id);
 	if (exe_fd < 0)
-- 
1.8.3.1