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Fix buffer overflows when argv[0] or env variables are longer than PATH_MAX #38

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Fix buffer overflows when argv[0] or env variables are longer than PATH_MAX #38

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3b1499f
Fix buffer overflows when argv[0] or env variables are longer than PA…
l-pt Jul 5, 2024
a98643b
Extract TARGET_APPIMAGE variable, initialize argv0_path to avoid strcpy
l-pt Jul 8, 2024
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29 changes: 21 additions & 8 deletions src/runtime/runtime.c
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Original file line number Diff line number Diff line change
Expand Up @@ -1332,7 +1332,7 @@ char* appimage_hexlify(const char* bytes, const size_t numBytes) {
}

int main(int argc, char* argv[]) {
char appimage_path[PATH_MAX];
char appimage_path[PATH_MAX] = "/proc/self/exe";
char argv0_path[PATH_MAX];
char* arg;

Expand All @@ -1342,12 +1342,20 @@ int main(int argc, char* argv[]) {
* change any time. Do not rely on it being present. We might even limit this
* functionality specifically for builds used by appimaged.
*/
if (getenv("TARGET_APPIMAGE") == NULL) {
strcpy(appimage_path, "/proc/self/exe");
strcpy(argv0_path, argv[0]);
const char* const TARGET_APPIMAGE = getenv("TARGET_APPIMAGE");
if (TARGET_APPIMAGE == NULL) {
char *res = memccpy(argv0_path, argv[0], '\0', sizeof(argv0_path));
if (res == NULL) {
fprintf(stderr, "Program name too big\n");
exit(EXIT_EXECERROR);
}
} else {
strcpy(appimage_path, getenv("TARGET_APPIMAGE"));
strcpy(argv0_path, getenv("TARGET_APPIMAGE"));
char *res1 = memccpy(appimage_path, TARGET_APPIMAGE, '\0', sizeof(appimage_path));
char *res2 = memccpy(argv0_path, TARGET_APPIMAGE, '\0', sizeof(argv0_path));
if (res1 == NULL || res2 == NULL) {
fprintf(stderr, "TARGET_APPIMAGE environment variable too big\n");
exit(EXIT_EXECERROR);
}
}

// temporary directories are required in a few places
Expand All @@ -1356,8 +1364,13 @@ int main(int argc, char* argv[]) {

{
const char* const TMPDIR = getenv("TMPDIR");
if (TMPDIR != NULL)
strcpy(temp_base, getenv("TMPDIR"));
if (TMPDIR != NULL) {
char *res = memccpy(temp_base, TMPDIR, '\0', sizeof(temp_base));
if (res == NULL) {
fprintf(stderr, "TMPDIR environemnt variable too big\n");
exit(EXIT_EXECERROR);
}
}
}

fs_offset = appimage_get_elf_size(appimage_path);
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