Merge tag 'pstore-v4.20-rc5' of git://git.kernel.org/pub/scm/linux/kernel/git/kees...

Pull pstore fix from Kees Cook:
 "Fix corrupted compression due to unlucky size choice with ECC"

* tag 'pstore-v4.20-rc5' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux:
  pstore/ram: Correctly calculate usable PRZ bytes

diff --git a/fs/pstore/ram.c b/fs/pstore/ram.c
index ffcff6516e89cccfcbbc138a6d7331e4ca9fb63b..e02a9039b5ea4410d3b3a986d7f4b6566e196eff 100644 (file)
--- a/fs/pstore/ram.c
+++ b/fs/pstore/ram.c
@@ -816,17 +816,14 @@ static int ramoops_probe(struct platform_device *pdev)
 
        cxt->pstore.data = cxt;
        /*
-        * Console can handle any buffer size, so prefer LOG_LINE_MAX. If we
-        * have to handle dumps, we must have at least record_size buffer. And
-        * for ftrace, bufsize is irrelevant (if bufsize is 0, buf will be
-        * ZERO_SIZE_PTR).
+        * Since bufsize is only used for dmesg crash dumps, it
+        * must match the size of the dprz record (after PRZ header
+        * and ECC bytes have been accounted for).
         */
-       if (cxt->console_size)
-               cxt->pstore.bufsize = 1024; /* LOG_LINE_MAX */
-       cxt->pstore.bufsize = max(cxt->record_size, cxt->pstore.bufsize);
-       cxt->pstore.buf = kmalloc(cxt->pstore.bufsize, GFP_KERNEL);
+       cxt->pstore.bufsize = cxt->dprzs[0]->buffer_size;
+       cxt->pstore.buf = kzalloc(cxt->pstore.bufsize, GFP_KERNEL);
        if (!cxt->pstore.buf) {
-               pr_err("cannot allocate pstore buffer\n");
+               pr_err("cannot allocate pstore crash dump buffer\n");
                err = -ENOMEM;
                goto fail_clear;
        }

diff --git a/include/linux/pstore.h b/include/linux/pstore.h
index a15bc4d487528f4f4301fdb9f30d465799637652..30fcec375a3af2d8b0ee305b7c540a15080847d2 100644 (file)
--- a/include/linux/pstore.h
+++ b/include/linux/pstore.h
@@ -90,7 +90,10 @@ struct pstore_record {
  *
  * @buf_lock:  spinlock to serialize access to @buf
  * @buf:       preallocated crash dump buffer
- * @bufsize:   size of @buf available for crash dump writes
+ * @bufsize:   size of @buf available for crash dump bytes (must match
+ *             smallest number of bytes available for writing to a
+ *             backend entry, since compressed bytes don't take kindly
+ *             to being truncated)
  *
  * @read_mutex:        serializes @open, @read, @close, and @erase callbacks
  * @flags:     bitfield of frontends the backend can accept writes for