Linux-EFI Archive on lore.kernel.org
 help / color / Atom feed
* [PATCH] efivarfs: revert "fix memory leak in efivarfs_create()"
@ 2020-11-25  7:53 Ard Biesheuvel
  2020-11-25  8:05 ` Oleksandr Natalenko
  2020-11-25 10:27 ` Oleksandr Natalenko
  0 siblings, 2 replies; 9+ messages in thread
From: Ard Biesheuvel @ 2020-11-25  7:53 UTC (permalink / raw)
  To: linux-efi
  Cc: oleksandr, jk, mjg59, David.Laight, Ard Biesheuvel,
	Vamshi K Sthambamkadi

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@gmail.com>
Fixes: fe5186cf12e3 ("efivarfs: fix memory leak in efivarfs_create()")
Reported-by: David Laight <David.Laight@aculab.com>
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
---
 fs/efivarfs/inode.c | 1 +
 fs/efivarfs/super.c | 1 -
 2 files changed, 1 insertion(+), 1 deletion(-)

diff --git a/fs/efivarfs/inode.c b/fs/efivarfs/inode.c
index 96c0c86f3fff..38324427a2b3 100644
--- a/fs/efivarfs/inode.c
+++ b/fs/efivarfs/inode.c
@@ -103,6 +103,7 @@ 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 f943fd0b0699..15880a68faad 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 = {
-- 
2.17.1


^ permalink raw reply	[flat|nested] 9+ messages in thread

end of thread, back to index

Thread overview: 9+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2020-11-25  7:53 [PATCH] efivarfs: revert "fix memory leak in efivarfs_create()" Ard Biesheuvel
2020-11-25  8:05 ` Oleksandr Natalenko
2020-11-25  8:05   ` Ard Biesheuvel
2020-11-25  8:25     ` Greg Kroah-Hartman
2020-11-25 10:27 ` Oleksandr Natalenko
2020-11-25 10:28   ` Ard Biesheuvel
2020-11-27 16:50     ` Jonathon Fernyhough
2020-11-27 16:58       ` Ard Biesheuvel
2020-11-27 16:59       ` Oleksandr Natalenko

Linux-EFI Archive on lore.kernel.org

Archives are clonable:
	git clone --mirror https://lore.kernel.org/linux-efi/0 linux-efi/git/0.git

	# If you have public-inbox 1.1+ installed, you may
	# initialize and index your mirror using the following commands:
	public-inbox-init -V2 linux-efi linux-efi/ https://lore.kernel.org/linux-efi \
		linux-efi@vger.kernel.org
	public-inbox-index linux-efi

Example config snippet for mirrors

Newsgroup available over NNTP:
	nntp://nntp.lore.kernel.org/org.kernel.vger.linux-efi


AGPL code for this site: git clone https://public-inbox.org/public-inbox.git