Currently, pstore_mkfile() performs a memcpy() of the record contents,
so it can live anywhere. However, this is needlessly wasteful. In
preparation of pstore_mkfile() keeping the record contents, always
allocate a buffer for the contents.
Signed-off-by: Kees Cook <keescook@xxxxxxxxxxxx>
---
fs/pstore/platform.c | 38 ++++++++++++++++++++++++--------------
1 file changed, 24 insertions(+), 14 deletions(-)
diff --git a/fs/pstore/platform.c b/fs/pstore/platform.c
index 879658b4c679..c0d401e732e6 100644
--- a/fs/pstore/platform.c
+++ b/fs/pstore/platform.c
@@ -768,6 +768,7 @@ EXPORT_SYMBOL_GPL(pstore_unregister);
static void decompress_record(struct pstore_record *record)
{
int unzipped_len;
+ char *decompressed;
/* Only PSTORE_TYPE_DMESG support compression. */
if (!record->compressed || record->type != PSTORE_TYPE_DMESG) {
@@ -783,17 +784,29 @@ static void decompress_record(struct pstore_record *record)
unzipped_len = pstore_decompress(record->buf, big_oops_buf,
record->size, big_oops_buf_sz);
- if (unzipped_len > 0) {
- if (record->ecc_notice_size)
- memcpy(big_oops_buf + unzipped_len,
- record->buf + record->size,
- record->ecc_notice_size);
- kfree(record->buf);
- record->buf = big_oops_buf;
- record->size = unzipped_len;
- record->compressed = false;
- } else
+ if (unzipped_len <= 0) {
pr_err("decompression failed: %d\n", unzipped_len);
+ return;
+ }
+
+ /* Build new buffer for decompressed contents. */
+ decompressed = kmalloc(unzipped_len + record->ecc_notice_size,
+ GFP_KERNEL);
+ if (!decompressed) {
+ pr_err("decompression ran out of memory\n");
+ return;
+ }
+ memcpy(decompressed, big_oops_buf, unzipped_len);
+
+ /* Append ECC notice to decompressed buffer. */
+ memcpy(decompressed + unzipped_len, record->buf + record->size,
+ record->ecc_notice_size);
+
+ /* Swap out compresed contents with decompressed contents. */
+ kfree(record->buf);
+ record->buf = decompressed;
+ record->size = unzipped_len;
+ record->compressed = false;
}
/*
@@ -819,13 +832,10 @@ void pstore_get_records(int quiet)
decompress_record(&record);
rc = pstore_mkfile(&record);
- /* Free buffer other than big oops */
- if (record.buf != big_oops_buf)
- kfree(record.buf);
-
if (rc && (rc != -EEXIST || !quiet))
failed++;
+ kfree(record.buf);
memset(&record, 0, sizeof(record));
record.psi = psi;
}
--
2.7.4
--
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