[PATCH] pstore: ramoops: support pmsg size larger than kmalloc limitation

From: Yuxiao Zhang <yuxiaozhang@google.com>
To: Kees Cook <keescook@chromium.org>,
	Tony Luck <tony.luck@intel.com>,
	"'Guilherme G . Piccoli'" <gpiccoli@igalia.com>,
	Greg KH <gregkh@linuxfoundation.org>,
	linux-hardening@vger.kernel.org
Cc: linux-kernel@vger.kernel.org, wak@google.com,
	Yuxiao Zhang <yuxiaozhang@google.com>
Subject: [PATCH] pstore: ramoops: support pmsg size larger than kmalloc limitation
Date: Tue, 27 Jun 2023 13:25:41 -0700	[thread overview]
Message-ID: <20230627202540.881909-2-yuxiaozhang@google.com> (raw)

Current pmsg implementation is using kmalloc for pmsg record buffer,
which has max size limits based on page size. Currently even we
allocate enough space with pmsg-size, pmsg will still fail if the
file size is larger than what kmalloc allowed.

Since we don't need physical contiguous memory for pmsg buffer
, we can use kvmalloc to avoid such limitation.

Signed-off-by: Yuxiao Zhang <yuxiaozhang@google.com>
---
 fs/pstore/inode.c    | 2 +-
 fs/pstore/platform.c | 9 +++++----
 fs/pstore/ram.c      | 5 +++--
 fs/pstore/ram_core.c | 3 ++-
 4 files changed, 11 insertions(+), 8 deletions(-)

diff --git a/fs/pstore/inode.c b/fs/pstore/inode.c
index ffbadb8b3032..df7fb2ad4599 100644
--- a/fs/pstore/inode.c
+++ b/fs/pstore/inode.c
@@ -54,7 +54,7 @@ static void free_pstore_private(struct pstore_private *private)
 	if (!private)
 		return;
 	if (private->record) {
-		kfree(private->record->buf);
+		kvfree(private->record->buf);
 		kfree(private->record->priv);
 		kfree(private->record);
 	}
diff --git a/fs/pstore/platform.c b/fs/pstore/platform.c
index cbc0b468c1ab..f51e9460ac9d 100644
--- a/fs/pstore/platform.c
+++ b/fs/pstore/platform.c
@@ -32,6 +32,7 @@
 #include <linux/uaccess.h>
 #include <linux/jiffies.h>
 #include <linux/workqueue.h>
+#include <linux/mm.h>
 
 #include "internal.h"
 
@@ -549,7 +550,7 @@ static int pstore_write_user_compat(struct pstore_record *record,
 	if (record->buf)
 		return -EINVAL;
 
-	record->buf = memdup_user(buf, record->size);
+	record->buf = vmemdup_user(buf, record->size);
 	if (IS_ERR(record->buf)) {
 		ret = PTR_ERR(record->buf);
 		goto out;
@@ -557,7 +558,7 @@ static int pstore_write_user_compat(struct pstore_record *record,
 
 	ret = record->psi->write(record);
 
-	kfree(record->buf);
+	kvfree(record->buf);
 out:
 	record->buf = NULL;
 
@@ -730,7 +731,7 @@ static void decompress_record(struct pstore_record *record)
 		return;
 
 	/* Swap out compressed contents with decompressed contents. */
-	kfree(record->buf);
+	kvfree(record->buf);
 	record->buf = unzipped;
 	record->size = unzipped_len;
 	record->compressed = false;
@@ -783,7 +784,7 @@ void pstore_get_backend_records(struct pstore_info *psi,
 		rc = pstore_mkfile(root, record);
 		if (rc) {
 			/* pstore_mkfile() did not take record, so free it. */
-			kfree(record->buf);
+			kvfree(record->buf);
 			kfree(record->priv);
 			kfree(record);
 			if (rc != -EEXIST || !quiet)
diff --git a/fs/pstore/ram.c b/fs/pstore/ram.c
index ade66dbe5f39..296465b14fa9 100644
--- a/fs/pstore/ram.c
+++ b/fs/pstore/ram.c
@@ -20,6 +20,7 @@
 #include <linux/compiler.h>
 #include <linux/of.h>
 #include <linux/of_address.h>
+#include <linux/mm.h>
 
 #include "internal.h"
 #include "ram_internal.h"
@@ -268,7 +269,7 @@ static ssize_t ramoops_pstore_read(struct pstore_record *record)
 	/* ECC correction notice */
 	record->ecc_notice_size = persistent_ram_ecc_string(prz, NULL, 0);
 
-	record->buf = kmalloc(size + record->ecc_notice_size + 1, GFP_KERNEL);
+	record->buf = kvmalloc(size + record->ecc_notice_size + 1, GFP_KERNEL);
 	if (record->buf == NULL) {
 		size = -ENOMEM;
 		goto out;
@@ -282,7 +283,7 @@ static ssize_t ramoops_pstore_read(struct pstore_record *record)
 
 out:
 	if (free_prz) {
-		kfree(prz->old_log);
+		kvfree(prz->old_log);
 		kfree(prz);
 	}
 
diff --git a/fs/pstore/ram_core.c b/fs/pstore/ram_core.c
index 966191d3a5ba..3453d493ec27 100644
--- a/fs/pstore/ram_core.c
+++ b/fs/pstore/ram_core.c
@@ -17,6 +17,7 @@
 #include <linux/slab.h>
 #include <linux/uaccess.h>
 #include <linux/vmalloc.h>
+#include <linux/mm.h>
 #include <asm/page.h>
 
 #include "ram_internal.h"
@@ -385,7 +386,7 @@ void *persistent_ram_old(struct persistent_ram_zone *prz)
 
 void persistent_ram_free_old(struct persistent_ram_zone *prz)
 {
-	kfree(prz->old_log);
+	kvfree(prz->old_log);
 	prz->old_log = NULL;
 	prz->old_log_size = 0;
 }
-- 
2.41.0.162.gfafddb0af9-goog
