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mldr: Use the correct addresses for prctl calls
prctl actually expects pointers to (contiguous) string contents, not to string pointer arrays. This fixes `ps` output for mldr processes.
+19
-8
+19
-8
src/startup/mldr/stack.c
+19
-8
src/startup/mldr/stack.c
···
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}
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// Fill in argv pointers
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+
// NOTE: the prctl code assumes that the current argv array points to contiguous strings.
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// this is not necessarily true, although AFAIK this is always true on Linux.
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// nonetheless, we should probably not assume this.
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argv = sp;
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-
if (prctl(PR_SET_MM, PR_SET_MM_ARG_START, argv, 0, 0) < 0) {
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+
uintptr_t arg_space_ptr = lr->argv[0];
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if (prctl(PR_SET_MM, PR_SET_MM_ARG_START, arg_space_ptr, 0, 0) < 0) {
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// maybe arg_end was behind arg_start; try moving it first
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-
if (prctl(PR_SET_MM, PR_SET_MM_ARG_END, argv, 0, 0) < 0) {
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if (prctl(PR_SET_MM, PR_SET_MM_ARG_END, arg_space_ptr, 0, 0) < 0) {
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fprintf(stderr, "Failed to set arg end\n");
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exit(1);
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}
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-
if (prctl(PR_SET_MM, PR_SET_MM_ARG_START, argv, 0, 0) < 0) {
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+
if (prctl(PR_SET_MM, PR_SET_MM_ARG_START, arg_space_ptr, 0, 0) < 0) {
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fprintf(stderr, "Failed to set arg start\n");
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exit(1);
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}
···
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fprintf(stderr, "Failed to copy an argument pointer to stack\n");
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exit(1);
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}
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+
arg_space_ptr += strlen(lr->argv[i]) + 1;
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}
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if (__put_user((user_long_t) 0, argv++))
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{
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fprintf(stderr, "Failed to null-terminate the argument pointer array\n");
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exit(1);
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}
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-
if (prctl(PR_SET_MM, PR_SET_MM_ARG_END, argv, 0, 0) < 0) {
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if (prctl(PR_SET_MM, PR_SET_MM_ARG_END, arg_space_ptr, 0, 0) < 0) {
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fprintf(stderr, "Failed to set arg end\n");
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exit(1);
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}
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// Fill in envp pointers
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+
// NOTE: same as for argv; here we assume the envp strings are contiguous
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envp = argv;
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-
if (prctl(PR_SET_MM, PR_SET_MM_ENV_START, envp, 0, 0) < 0) {
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+
uintptr_t env_space_ptr = lr->envp[0];
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if (prctl(PR_SET_MM, PR_SET_MM_ENV_START, env_space_ptr, 0, 0) < 0) {
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// maybe env_end was behind env_start; try moving it first
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-
if (prctl(PR_SET_MM, PR_SET_MM_ENV_END, envp, 0, 0) < 0) {
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if (prctl(PR_SET_MM, PR_SET_MM_ENV_END, env_space_ptr, 0, 0) < 0) {
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fprintf(stderr, "Failed to set env end\n");
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exit(1);
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}
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if (prctl(PR_SET_MM, PR_SET_MM_ENV_START, envp, 0, 0) < 0) {
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+
if (prctl(PR_SET_MM, PR_SET_MM_ENV_START, env_space_ptr, 0, 0) < 0) {
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fprintf(stderr, "Failed to set env start\n");
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exit(1);
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}
···
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// Don't pass these special env vars down to userland
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#define SKIP_VAR(_name) \
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if (len > sizeof(_name) - 1 && strncmp(lr->envp[i], _name, sizeof(_name) - 1) == 0) { \
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env_space_ptr += strlen(lr->envp[i]) + 1; \
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continue; \
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}
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···
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fprintf(stderr, "Failed to copy an environment variable pointer to stack\n");
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exit(1);
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}
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+
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env_space_ptr += strlen(lr->envp[i]) + 1;
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}
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if (__put_user((user_long_t) 0, envp++))
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{
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fprintf(stderr, "Failed to null-terminate the environment variable pointer array\n");
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exit(1);
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}
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-
if (prctl(PR_SET_MM, PR_SET_MM_ENV_END, envp, 0, 0) < 0) {
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// FIXME: this might include variables that we've skipped
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if (prctl(PR_SET_MM, PR_SET_MM_ENV_END, env_space_ptr, 0, 0) < 0) {
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fprintf(stderr, "Failed to set env end\n");
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exit(1);
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}