From ee338a256ee8dff064fd3920a2efe642ef1d3cfa Mon Sep 17 00:00:00 2001 From: Stefano Brivio Date: Thu, 11 Apr 2024 17:48:23 +0200 Subject: pasta, util: Align stack area for clones to maximum natural alignment Given that we use this stack pointer as a location to store arbitrary data types from the cloned process, we need to guarantee that its alignment matches any of those possible data types. runsisi reports that pasta gets a SIGBUS in pasta_open_ns() on aarch64, where the alignment requirement for stack pointers is a 16 bytes (same as the size of a long double), and similar requirements actually apply to most architectures we run on. Reported-by: runsisi Link: https://bugs.passt.top/show_bug.cgi?id=85 Signed-off-by: Stefano Brivio Reviewed-by: David Gibson --- pasta.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) (limited to 'pasta.c') diff --git a/pasta.c b/pasta.c index e73b5af..31e1e00 100644 --- a/pasta.c +++ b/pasta.c @@ -211,12 +211,13 @@ static int pasta_spawn_cmd(void *arg) void pasta_start_ns(struct ctx *c, uid_t uid, gid_t gid, int argc, char *argv[]) { + char ns_fn_stack[NS_FN_STACK_SIZE] + __attribute__ ((aligned(__alignof__(max_align_t)))); struct pasta_spawn_cmd_arg arg = { .exe = argv[0], .argv = argv, }; char uidmap[BUFSIZ], gidmap[BUFSIZ]; - char ns_fn_stack[NS_FN_STACK_SIZE]; char *sh_argv[] = { NULL, NULL }; char sh_arg0[PATH_MAX + 1]; sigset_t set; -- cgit v1.2.3