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kernel: alloc path on stack; don't follow symlink
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tiann committed Mar 27, 2024
1 parent ac56a01 commit eb24884
Showing 1 changed file with 9 additions and 8 deletions.
17 changes: 9 additions & 8 deletions kernel/throne_tracker.c
Original file line number Diff line number Diff line change
@@ -120,25 +120,26 @@ FILLDIR_RETURN_TYPE my_actor(struct dir_context *ctx, const char *name,
struct my_dir_context *my_ctx =
container_of(ctx, struct my_dir_context, ctx);
struct file *file;
char *dirpath;
char dirpath[384]; // 384 is enough for /data/app/<package>/base.apk

if (!my_ctx) {
pr_err("Invalid context\n");
return FILLDIR_ACTOR_STOP;
}
if (my_ctx->stop && *my_ctx->stop) {
pr_info("Stop searching\n");
return FILLDIR_ACTOR_STOP;
}

if (!strncmp(name, "..", namelen) || !strncmp(name, ".", namelen))
return FILLDIR_ACTOR_CONTINUE; // Skip "." and ".."

dirpath = kmalloc(PATH_MAX, GFP_KERNEL);
if (!dirpath) {
return FILLDIR_ACTOR_STOP; // Failed to obtain directory path
if (snprintf(dirpath, sizeof(dirpath), "%s/%.*s", my_ctx->parent_dir,
namelen, name) >= sizeof(dirpath)) {
pr_err("Path too long: %s/%.*s\n", my_ctx->parent_dir, namelen,
name);
return FILLDIR_ACTOR_CONTINUE;
}
snprintf(dirpath, PATH_MAX, "%s/%.*s", my_ctx->parent_dir, namelen,
name);

if (d_type == DT_DIR && my_ctx->depth > 0 &&
(my_ctx->stop && !*my_ctx->stop)) {
@@ -148,7 +149,7 @@ FILLDIR_RETURN_TYPE my_actor(struct dir_context *ctx, const char *name,
my_ctx->private_data,
.depth = my_ctx->depth - 1,
.stop = my_ctx->stop };
file = ksu_filp_open_compat(dirpath, O_RDONLY, 0);
file = ksu_filp_open_compat(dirpath, O_RDONLY | O_NOFOLLOW, 0);
if (IS_ERR(file)) {
pr_err("Failed to open directory: %s, err: %ld\n",
dirpath, PTR_ERR(file));
@@ -185,7 +186,7 @@ void search_manager(const char *path, int depth, struct list_head *uid_data)
.depth = depth,
.stop = &stop };

file = ksu_filp_open_compat(path, O_RDONLY, 0);
file = ksu_filp_open_compat(path, O_RDONLY | O_NOFOLLOW, 0);
if (IS_ERR(file)) {
pr_err("Failed to open directory: %s\n", path);
return;

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