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pstore: Avoid potential infinite loop

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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>
This commit is contained in:
Kees Cook 2017-05-16 12:03:31 -07:00
parent f6525b96dd
commit 656de42e83
1 changed files with 6 additions and 2 deletions
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8
fs/pstore/platform.c
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@ -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 @@ out:
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)