linux-kernel - [PATCH 5.4 69/98] efivarfs: revert "fix memory leak in efivarfs

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-Id: <20201201084658.465023247@linuxfoundation.org>
Date:   Tue,  1 Dec 2020 09:53:46 +0100
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org,
        Vamshi K Sthambamkadi <vamshi.k.sthambamkadi@...il.com>,
        David Laight <David.Laight@...lab.com>,
        Ard Biesheuvel <ardb@...nel.org>,
        Sasha Levin <sashal@...nel.org>
Subject: [PATCH 5.4 69/98] efivarfs: revert "fix memory leak in efivarfs_create()"

From: Ard Biesheuvel <ardb@...nel.org>

[ Upstream commit ff04f3b6f2e27f8ae28a498416af2a8dd5072b43 ]

The memory leak addressed by commit fe5186cf12e3 is a false positive:
all allocations are recorded in a linked list, and freed when the
filesystem is unmounted. This leads to double frees, and as reported
by David, leads to crashes if SLUB is configured to self destruct when
double frees occur.

So drop the redundant kfree() again, and instead, mark the offending
pointer variable so the allocation is ignored by kmemleak.

Cc: Vamshi K Sthambamkadi <vamshi.k.sthambamkadi@...il.com>
Fixes: fe5186cf12e3 ("efivarfs: fix memory leak in efivarfs_create()")
Reported-by: David Laight <David.Laight@...lab.com>
Signed-off-by: Ard Biesheuvel <ardb@...nel.org>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 fs/efivarfs/inode.c | 2 ++
 fs/efivarfs/super.c | 1 -
 2 files changed, 2 insertions(+), 1 deletion(-)

diff --git a/fs/efivarfs/inode.c b/fs/efivarfs/inode.c
index 96c0c86f3fffe..0297ad95eb5cc 100644
--- a/fs/efivarfs/inode.c
+++ b/fs/efivarfs/inode.c
@@ -7,6 +7,7 @@
 #include <linux/efi.h>
 #include <linux/fs.h>
 #include <linux/ctype.h>
+#include <linux/kmemleak.h>
 #include <linux/slab.h>
 #include <linux/uuid.h>
 
@@ -103,6 +104,7 @@ static int efivarfs_create(struct inode *dir, struct dentry *dentry,
 	var->var.VariableName[i] = '\0';
 
 	inode->i_private = var;
+	kmemleak_ignore(var);
 
 	err = efivar_entry_add(var, &efivarfs_list);
 	if (err)
diff --git a/fs/efivarfs/super.c b/fs/efivarfs/super.c
index edcd6769a94b4..9760a52800b42 100644
--- a/fs/efivarfs/super.c
+++ b/fs/efivarfs/super.c
@@ -21,7 +21,6 @@ LIST_HEAD(efivarfs_list);
 static void efivarfs_evict_inode(struct inode *inode)
 {
 	clear_inode(inode);
-	kfree(inode->i_private);
 }
 
 static const struct super_operations efivarfs_ops = {
-- 
2.27.0