pstore: Avoid potential infinite loop
If a backend does not correctly iterate through its records, pstore will
get stuck loading entries. Detect this with a large record count, and
announce if we ever hit the limit. This will let future backend reading
bugs less annoying to debug. Additionally adjust the error about
pstore_mkfile() failing.
Signed-off-by: Kees Cook <keescook@chromium.org>
diff --git a/fs/pstore/platform.c b/fs/pstore/platform.c
index 4c5cd93..d8289ce 100644
--- a/fs/pstore/platform.c
+++ b/fs/pstore/platform.c
@@ -822,6 +822,7 @@ void pstore_get_backend_records(struct pstore_info *psi,
struct dentry *root, int quiet)
{
int failed = 0;
+ unsigned int stop_loop = 65536;
if (!psi || !root)
return;
@@ -835,7 +836,7 @@ void pstore_get_backend_records(struct pstore_info *psi,
* may reallocate record.buf. On success, pstore_mkfile() will keep
* the record.buf, so free it only on failure.
*/
- for (;;) {
+ for (; stop_loop; stop_loop--) {
struct pstore_record *record;
int rc;
@@ -870,8 +871,11 @@ void pstore_get_backend_records(struct pstore_info *psi,
mutex_unlock(&psi->read_mutex);
if (failed)
- pr_warn("failed to load %d record(s) from '%s'\n",
+ pr_warn("failed to create %d record(s) from '%s'\n",
failed, psi->name);
+ if (!stop_loop)
+ pr_err("looping? Too many records seen from '%s'\n",
+ psi->name);
}
static void pstore_dowork(struct work_struct *work)