From 7e8cc8dce17574e432945fa75882cd401c3ef673 Mon Sep 17 00:00:00 2001 From: Kees Cook Date: Sat, 4 Mar 2017 22:28:46 -0800 Subject: [PATCH] pstore: Always allocate buffer for decompression 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 --- 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; } -- 2.20.1