On 25.11.2020 08:53, Ard Biesheuvel wrote:
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@xxxxxxxxx>
Fixes: fe5186cf12e3 ("efivarfs: fix memory leak in efivarfs_create()")
Reported-by: David Laight <David.Laight@xxxxxxxxxx>
Signed-off-by: Ard Biesheuvel <ardb@xxxxxxxxxx>
---
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);
Do we need to do this as well:
#include <linux/kmemleak.h>
?
Because otherwise for 5.9 I get:
[ 148s] fs/efivarfs/inode.c: In function 'efivarfs_create':
[ 148s] fs/efivarfs/inode.c:106:2: error: implicit declaration of
function 'kmemleak_ignore' [-Werror=implicit-function-declaration]
[ 148s] 106 | kmemleak_ignore(var);
[ 148s] | ^~~~~~~~~~~~~~~
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 = {
--
Oleksandr Natalenko (post-factum)
